Commit Graph

5673 Commits

Author SHA1 Message Date
Pekka Enberg 42616cacf8 Merge branch 'slab/urgent' into slab/next 2011-11-27 22:08:03 +02:00
Eric Dumazet bc6697d8a5 slub: avoid potential NULL dereference or corruption
show_slab_objects() can trigger NULL dereferences or memory corruption.

Another cpu can change its c->page to NULL or c->node to NUMA_NO_NODE
while we use them.

Use ACCESS_ONCE(c->page) and ACCESS_ONCE(c->node) to make sure this
cannot happen.

Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-24 08:44:19 +02:00
Christoph Lameter 42d623a8cd slub: use irqsafe_cpu_cmpxchg for put_cpu_partial
The cmpxchg must be irq safe. The fallback for this_cpu_cmpxchg only
disables preemption which results in per cpu partial page operation
potentially failing on non x86 platforms.

This patch fixes the following problem reported by Christian Kujau:

  I seem to hit it with heavy disk & cpu IO is in progress on this
  PowerBook
  G4. Full dmesg & .config: http://nerdbynature.de/bits/3.2.0-rc1/oops/

  I've enabled some debug options and now it really points to slub.c:2166

    http://nerdbynature.de/bits/3.2.0-rc1/oops/oops4m.jpg

  With debug options enabled I'm currently in the xmon debugger, not sure
  what to make of it yet, I'll try to get something useful out of it :)

Reported-by: Christian Kujau <lists@nerdbynature.de>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-24 08:44:14 +02:00
Rafael J. Wysocki 986b11c3ee Merge branch 'pm-freezer' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc into pm-freezer
* 'pm-freezer' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc: (24 commits)
  freezer: fix wait_event_freezable/__thaw_task races
  freezer: kill unused set_freezable_with_signal()
  dmatest: don't use set_freezable_with_signal()
  usb_storage: don't use set_freezable_with_signal()
  freezer: remove unused @sig_only from freeze_task()
  freezer: use lock_task_sighand() in fake_signal_wake_up()
  freezer: restructure __refrigerator()
  freezer: fix set_freezable[_with_signal]() race
  freezer: remove should_send_signal() and update frozen()
  freezer: remove now unused TIF_FREEZE
  freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE
  cgroup_freezer: prepare for removal of TIF_FREEZE
  freezer: clean up freeze_processes() failure path
  freezer: kill PF_FREEZING
  freezer: test freezable conditions while holding freezer_lock
  freezer: make freezing indicate freeze condition in effect
  freezer: use dedicated lock instead of task_lock() + memory barrier
  freezer: don't distinguish nosig tasks on thaw
  freezer: remove racy clear_freeze_flag() and set PF_NOFREEZE on dead tasks
  freezer: rename thaw_process() to __thaw_task() and simplify the implementation
  ...
2011-11-23 21:09:02 +01:00
Dave Young 67589c7145 percpu: explain why per_cpu_ptr_to_phys() is more complicated than necessary
Add comments about current per_cpu_ptr_to_phys implementation to
explain why the logic is more complicated than necessary.

-tj: relocated comment into kerneldoc comment

Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2011-11-23 08:20:53 -08:00
Linus Torvalds 8ba8ed54de Merge branch 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux
* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: remove vm_dirties and task->dirties
  writeback: hard throttle 1000+ dd on a slow USB stick
  mm: Make task in balance_dirty_pages() killable
2011-11-22 08:22:48 -08:00
Tejun Heo a855b84c3d percpu: fix chunk range calculation
Percpu allocator recorded the cpus which map to the first and last
units in pcpu_first/last_unit_cpu respectively and used them to
determine the address range of a chunk - e.g. it assumed that the
first unit has the lowest address in a chunk while the last unit has
the highest address.

This simply isn't true.  Groups in a chunk can have arbitrary positive
or negative offsets from the previous one and there is no guarantee
that the first unit occupies the lowest offset while the last one the
highest.

Fix it by actually comparing unit offsets to determine cpus occupying
the lowest and highest offsets.  Also, rename pcu_first/last_unit_cpu
to pcpu_low/high_unit_cpu to avoid confusion.

The chunk address range is used to flush cache on vmalloc area
map/unmap and decide whether a given address is in the first chunk by
per_cpu_ptr_to_phys() and the bug was discovered by invalid
per_cpu_ptr_to_phys() translation for crash_note.

Kudos to Dave Young for tracking down the problem.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: WANG Cong <xiyou.wangcong@gmail.com>
Reported-by: Dave Young <dyoung@redhat.com>
Tested-by: Dave Young <dyoung@redhat.com>
LKML-Reference: <4EC21F67.10905@redhat.com>
Cc: stable @kernel.org
2011-11-22 08:09:46 -08:00
Bob Liu 90459ce06f percpu: rename pcpu_mem_alloc to pcpu_mem_zalloc
Currently pcpu_mem_alloc() is implemented always return zeroed memory.
So rename it to make user like pcpu_get_pages_and_bitmap() know don't
reinit it.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
2011-11-22 08:09:41 -08:00
Tejun Heo a5be2d0d1a freezer: rename thaw_process() to __thaw_task() and simplify the implementation
thaw_process() now has only internal users - system and cgroup
freezers.  Remove the unnecessary return value, rename, unexport and
collapse __thaw_process() into it.  This will help further updates to
the freezer code.

-v3: oom_kill grew a use of thaw_process() while this patch was
     pending.  Convert it to use __thaw_task() for now.  In the longer
     term, this should be handled by allowing tasks to die if killed
     even if it's frozen.

-v2: minor style update as suggested by Matt.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Paul Menage <menage@google.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
2011-11-21 12:32:23 -08:00
Tejun Heo 8a32c441c1 freezer: implement and use kthread_freezable_should_stop()
Writeback and thinkpad_acpi have been using thaw_process() to prevent
deadlock between the freezer and kthread_stop(); unfortunately, this
is inherently racy - nothing prevents freezing from happening between
thaw_process() and kthread_stop().

This patch implements kthread_freezable_should_stop() which enters
refrigerator if necessary but is guaranteed to return if
kthread_stop() is invoked.  Both thaw_process() users are converted to
use the new function.

Note that this deadlock condition exists for many of freezable
kthreads.  They need to be converted to use the new should_stop or
freezable workqueue.

Tested with synthetic test case.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Henrique de Moraes Holschuh <ibm-acpi@hmh.eng.br>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
2011-11-21 12:32:23 -08:00
Nicolas Pitre be9b7335e7 mm: add vm_area_add_early()
The existing vm_area_register_early() allows for early vmalloc space
allocation.  However upcoming cleanups in the ARM architecture require
that some fixed locations in the vmalloc area be reserved also very early.

The name "vm_area_register_early" would have been a good name for the
reservation part without the allocation.  Since it is already in use with
different semantics, let's create vm_area_add_early() instead.

Both vm_area_register_early() and vm_area_add_early() can be used together
meaning that the former is now implemented using the later where it is
ensured that no conflicting areas are added, but no attempt is made to
make the allocation scheme in vm_area_register_early() more sophisticated.
After all, you must know what you're doing when using those functions.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
2011-11-18 13:51:22 -05:00
Linus Torvalds b684452383 Merge branch 'stable/for-linus-fixes-3.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen
* 'stable/for-linus-fixes-3.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
  xen-gntalloc: signedness bug in add_grefs()
  xen-gntalloc: integer overflow in gntalloc_ioctl_alloc()
  xen-gntdev: integer overflow in gntdev_alloc_map()
  xen:pvhvm: enable PVHVM VCPU placement when using more than 32 CPUs.
  xen/balloon: Avoid OOM when requesting highmem
  xen: Remove hanging references to CONFIG_XEN_PLATFORM_PCI
  xen: map foreign pages for shared rings by updating the PTEs directly
2011-11-18 13:18:07 -02:00
Linus Torvalds 15bd1cfb30 Merge branch 'for-linus' of git://git.kernel.dk/linux-block
* 'for-linus' of git://git.kernel.dk/linux-block:
  block: add missed trace_block_plug
  paride: fix potential information leak in pg_read()
  bio: change some signed vars to unsigned
  block: avoid unnecessary plug list flush
  cciss: auto engage SCSI mid layer at driver load time
  loop: cleanup set_status interface
  include/linux/bio.h: use a static inline function for bio_integrity_clone()
  loop: prevent information leak after failed read
  block: Always check length of all iov entries in blk_rq_map_user_iov()
  The Windows driver .inf disables ASPM on all cciss devices. Do the same.
  backing-dev: ensure wakeup_timer is deleted
  block: Revert "[SCSI] genhd: add a new attribute "alias" in gendisk"
2011-11-18 09:34:35 -02:00
Wu Fengguang 468e6a20af writeback: remove vm_dirties and task->dirties
They are not used any more.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-11-17 20:49:06 +08:00
Wu Fengguang 1df647197c writeback: hard throttle 1000+ dd on a slow USB stick
The sleep based balance_dirty_pages() can pause at most MAX_PAUSE=200ms
on every 1 4KB-page, which means it cannot throttle a task under
4KB/200ms=20KB/s. So when there are more than 512 dd writing to a
10MB/s USB stick, its bdi dirty pages could grow out of control.

Even if we can increase MAX_PAUSE, the minimal (task_ratelimit = 1)
means a limit of 4KB/s.
                                                       
They can eventually be safeguarded by the global limit check 
(nr_dirty < dirty_thresh). However if someone is also writing to an 
HDD at the same time, it'll get poor HDD write performance.
                                                       
We at least want to maintain good write performance for other devices
when one device is attacked by some "massive parallel" workload, or
suffers from slow write bandwidth, or somehow get stalled due to some 
error condition (eg. NFS server not responding).

For a stalled device, we need to completely block its dirtiers, too,
before its bdi dirty pages grow all the way up to the global limit and
leave no space for the other functional devices.

So change the loop exit condition to

	/*
	 * Always enforce global dirty limit; also enforce bdi dirty limit
	 * if the normal max_pause sleeps cannot keep things under control.
	 */
	if (nr_dirty < dirty_thresh &&
	    (bdi_dirty < bdi_thresh || bdi->dirty_ratelimit > 1))
		break;

which can be further simplified to

	if (task_ratelimit)
		break;

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-11-17 20:39:32 +08:00
Wang Sheng-Hui 6416b9fa43 mm: cleanup the comment for head/tail pages of compound pages in mm/page_alloc.c
Only tail pages point at the head page using their ->first_page fields.

Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-11-17 10:53:50 +01:00
Dave Jones face37f5e6 slab: add taint flag outputting to debug paths.
When we get corruption reports, it's useful to see if the kernel was
tainted, to rule out problems we can't do anything about.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-16 21:14:44 +02:00
Dave Jones 265d47e711 slub: add taint flag outputting to debug paths
When we get corruption reports, it's useful to see if the kernel was
tainted, to rule out problems we can't do anything about.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-16 21:14:40 +02:00
David Vrabel cd12909cb5 xen: map foreign pages for shared rings by updating the PTEs directly
When mapping a foreign page with xenbus_map_ring_valloc() with the
GNTTABOP_map_grant_ref hypercall, set the GNTMAP_contains_pte flag and
pass a pointer to the PTE (in init_mm).

After the page is mapped, the usual fault mechanism can be used to
update additional MMs.  This allows the vmalloc_sync_all() to be
removed from alloc_vm_area().

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
[v1: Squashed fix by Michal for no-mmu case]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
2011-11-16 12:13:08 -05:00
Jan Kara 499d05ecf9 mm: Make task in balance_dirty_pages() killable
There is no reason why task in balance_dirty_pages() shouldn't be killable
and it helps in recovering from some error conditions (like when filesystem
goes in error state and cannot accept writeback anymore but we still want to
kill processes using it to be able to unmount it).

There will be follow up patches to further abort the generic_perform_write()
and other filesystem write loops, to avoid large write + SIGKILL combination
exceeding the dirty limit and possibly strange OOM.

Reported-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Tested-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-11-16 19:53:44 +08:00
Hillf Danton ea4039a34c hugetlb: release pages in the error path of hugetlb_cow()
If we fail to prepare an anon_vma, the {new, old}_page should be released,
or they will leak.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-15 22:41:52 -02:00
Michal Hocko 5aecc85abd oom: do not kill tasks with oom_score_adj OOM_SCORE_ADJ_MIN
Commit c9f01245 ("oom: remove oom_disable_count") has removed the
oom_disable_count counter which has been used for early break out from
oom_badness so we could never select a task with oom_score_adj set to
OOM_SCORE_ADJ_MIN (oom disabled).

Now that the counter is gone we are always going through heuristics
calculation and we always return a non zero positive value.  This means
that we can end up killing a task with OOM disabled because it is
indistinguishable from regular tasks with 1% resp.  CAP_SYS_ADMIN tasks
with 3% usage of memory or tasks with oom_score_adj set but OOM enabled.

Let's break out early if the task should have OOM disabled.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-15 22:41:51 -02:00
Shaohua Li 9ada19342b slub: move discard_slab out of node lock
Lockdep reports there is potential deadlock for slub node list_lock.
discard_slab() is called with the lock hold in unfreeze_partials(),
which could trigger a slab allocation, which could hold the lock again.

discard_slab() doesn't need hold the lock actually, if the slab is
already removed from partial list.

Acked-by: Christoph Lameter <cl@linux.com>
Reported-and-tested-by: Yong Zhang <yong.zhang0@gmail.com>
Reported-and-tested-by: Julie Sullivan <kernelmail.jms@gmail.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-15 20:41:00 +02:00
Shaohua Li f64ae042d9 slub: use correct parameter to add a page to partial list tail
unfreeze_partials() needs add the page to partial list tail, since such page
hasn't too many free objects. We now explictly use DEACTIVATE_TO_TAIL for this,
while DEACTIVATE_TO_TAIL != 1. This will cause performance regression (eg, more
lock contention in node->list_lock) without below fix.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-15 20:37:15 +02:00
Rabin Vincent 7a401a972d backing-dev: ensure wakeup_timer is deleted
bdi_prune_sb() in bdi_unregister() attempts to removes the bdi links
from all super_blocks and then del_timer_sync() the writeback timer.

However, this can race with __mark_inode_dirty(), leading to
bdi_wakeup_thread_delayed() rearming the writeback timer on the bdi
we're unregistering, after we've called del_timer_sync().

This can end up with the bdi being freed with an active timer inside it,
as in the case of the following dump after the removal of an SD card.

Fix this by redoing the del_timer_sync() in bdi_destory().

 ------------[ cut here ]------------
 WARNING: at /home/rabin/kernel/arm/lib/debugobjects.c:262 debug_print_object+0x9c/0xc8()
 ODEBUG: free active (active state 0) object type: timer_list hint: wakeup_timer_fn+0x0/0x180
 Modules linked in:
 Backtrace:
 [<c00109dc>] (dump_backtrace+0x0/0x110) from [<c0236e4c>] (dump_stack+0x18/0x1c)
  r6:c02bc638 r5:00000106 r4:c79f5d18 r3:00000000
 [<c0236e34>] (dump_stack+0x0/0x1c) from [<c0025e6c>] (warn_slowpath_common+0x54/0x6c)
 [<c0025e18>] (warn_slowpath_common+0x0/0x6c) from [<c0025f28>] (warn_slowpath_fmt+0x38/0x40)
  r8:20000013 r7:c780c6f0 r6:c031613c r5:c780c6f0 r4:c02b1b29
 r3:00000009
 [<c0025ef0>] (warn_slowpath_fmt+0x0/0x40) from [<c015eb4c>] (debug_print_object+0x9c/0xc8)
  r3:c02b1b29 r2:c02bc662
 [<c015eab0>] (debug_print_object+0x0/0xc8) from [<c015f574>] (debug_check_no_obj_freed+0xac/0x1dc)
  r6:c7964000 r5:00000001 r4:c7964000
 [<c015f4c8>] (debug_check_no_obj_freed+0x0/0x1dc) from [<c00a9e38>] (kmem_cache_free+0x88/0x1f8)
 [<c00a9db0>] (kmem_cache_free+0x0/0x1f8) from [<c014286c>] (blk_release_queue+0x70/0x78)
 [<c01427fc>] (blk_release_queue+0x0/0x78) from [<c015290c>] (kobject_release+0x70/0x84)
  r5:c79641f0 r4:c796420c
 [<c015289c>] (kobject_release+0x0/0x84) from [<c0153ce4>] (kref_put+0x68/0x80)
  r7:00000083 r6:c74083d0 r5:c015289c r4:c796420c
 [<c0153c7c>] (kref_put+0x0/0x80) from [<c01527d0>] (kobject_put+0x48/0x5c)
  r5:c79643b4 r4:c79641f0
 [<c0152788>] (kobject_put+0x0/0x5c) from [<c013ddd8>] (blk_cleanup_queue+0x68/0x74)
  r4:c7964000
 [<c013dd70>] (blk_cleanup_queue+0x0/0x74) from [<c01a6370>] (mmc_blk_put+0x78/0xe8)
  r5:00000000 r4:c794c400
 [<c01a62f8>] (mmc_blk_put+0x0/0xe8) from [<c01a64b4>] (mmc_blk_release+0x24/0x38)
  r5:c794c400 r4:c0322824
 [<c01a6490>] (mmc_blk_release+0x0/0x38) from [<c00de11c>] (__blkdev_put+0xe8/0x170)
  r5:c78d5e00 r4:c74083c0
 [<c00de034>] (__blkdev_put+0x0/0x170) from [<c00de2c0>] (blkdev_put+0x11c/0x12c)
  r8:c79f5f70 r7:00000001 r6:c74083d0 r5:00000083 r4:c74083c0
 r3:00000000
 [<c00de1a4>] (blkdev_put+0x0/0x12c) from [<c00b0724>] (kill_block_super+0x60/0x6c)
  r7:c7942300 r6:c79f4000 r5:00000083 r4:c74083c0
 [<c00b06c4>] (kill_block_super+0x0/0x6c) from [<c00b0a94>] (deactivate_locked_super+0x44/0x70)
  r6:c79f4000 r5:c031af64 r4:c794dc00 r3:c00b06c4
 [<c00b0a50>] (deactivate_locked_super+0x0/0x70) from [<c00b1358>] (deactivate_super+0x6c/0x70)
  r5:c794dc00 r4:c794dc00
 [<c00b12ec>] (deactivate_super+0x0/0x70) from [<c00c88b0>] (mntput_no_expire+0x188/0x194)
  r5:c794dc00 r4:c7942300
 [<c00c8728>] (mntput_no_expire+0x0/0x194) from [<c00c95e0>] (sys_umount+0x2e4/0x310)
  r6:c7942300 r5:00000000 r4:00000000 r3:00000000
 [<c00c92fc>] (sys_umount+0x0/0x310) from [<c000d940>] (ret_fast_syscall+0x0/0x30)
 ---[ end trace e5c83c92ada51c76 ]---

Cc: stable@kernel.org
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-11-11 13:29:04 +01:00
David Rientjes 3df1cccdfb slab: introduce slab_max_order kernel parameter
Introduce new slab_max_order kernel parameter which is the equivalent of
slub_max_order.

For immediate purposes, allows users to override the heuristic that sets
the max order to 1 by default if they have more than 32MB of RAM.  This
may result in page allocation failures if there is substantial
fragmentation.

Another usecase would be to increase the max order for better
performance.

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-10 21:25:30 +02:00
David Rientjes 543585cc5b slab: rename slab_break_gfp_order to slab_max_order
slab_break_gfp_order is more appropriately named slab_max_order since it
enforces the maximum order size of slabs as long as a single object will
still fit.

Also rename BREAK_GFP_ORDER_{LO,HI} accordingly.

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-10 21:25:30 +02:00
Wu Fengguang 3a73dbbc9b writeback: fix uninitialized task_ratelimit
In balance_dirty_pages() task_ratelimit may be not initialized
(initialization skiped by goto pause), and then used when calling
tracing hook.

Fix it by moving the task_ratelimit assignment before goto pause.

Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-11-07 19:19:28 +08:00
Linus Torvalds 32aaeffbd4 Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
  Revert "tracing: Include module.h in define_trace.h"
  irq: don't put module.h into irq.h for tracking irqgen modules.
  bluetooth: macroize two small inlines to avoid module.h
  ip_vs.h: fix implicit use of module_get/module_put from module.h
  nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
  include: replace linux/module.h with "struct module" wherever possible
  include: convert various register fcns to macros to avoid include chaining
  crypto.h: remove unused crypto_tfm_alg_modname() inline
  uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
  pm_runtime.h: explicitly requires notifier.h
  linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
  miscdevice.h: fix up implicit use of lists and types
  stop_machine.h: fix implicit use of smp.h for smp_processor_id
  of: fix implicit use of errno.h in include/linux/of.h
  of_platform.h: delete needless include <linux/module.h>
  acpi: remove module.h include from platform/aclinux.h
  miscdevice.h: delete unnecessary inclusion of module.h
  device_cgroup.h: delete needless include <linux/module.h>
  net: sch_generic remove redundant use of <linux/module.h>
  net: inet_timewait_sock doesnt need <linux/module.h>
  ...

Fix up trivial conflicts (other header files, and  removal of the ab3550 mfd driver) in
 - drivers/media/dvb/frontends/dibx000_common.c
 - drivers/media/video/{mt9m111.c,ov6650.c}
 - drivers/mfd/ab3550-core.c
 - include/linux/dmaengine.h
2011-11-06 19:44:47 -08:00
Linus Torvalds 208bca0860 Merge branch 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux
* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: Add a 'reason' to wb_writeback_work
  writeback: send work item to queue_io, move_expired_inodes
  writeback: trace event balance_dirty_pages
  writeback: trace event bdi_dirty_ratelimit
  writeback: fix ppc compile warnings on do_div(long long, unsigned long)
  writeback: per-bdi background threshold
  writeback: dirty position control - bdi reserve area
  writeback: control dirty pause time
  writeback: limit max dirty pause time
  writeback: IO-less balance_dirty_pages()
  writeback: per task dirty rate limit
  writeback: stabilize bdi->dirty_ratelimit
  writeback: dirty rate control
  writeback: add bg_threshold parameter to __bdi_update_bandwidth()
  writeback: dirty position control
  writeback: account per-bdi accumulated dirtied pages
2011-11-06 19:02:23 -08:00
Linus Torvalds b4fdcb02f1 Merge branch 'for-3.2/core' of git://git.kernel.dk/linux-block
* 'for-3.2/core' of git://git.kernel.dk/linux-block: (29 commits)
  block: don't call blk_drain_queue() if elevator is not up
  blk-throttle: use queue_is_locked() instead of lockdep_is_held()
  blk-throttle: Take blkcg->lock while traversing blkcg->policy_list
  blk-throttle: Free up policy node associated with deleted rule
  block: warn if tag is greater than real_max_depth.
  block: make gendisk hold a reference to its queue
  blk-flush: move the queue kick into
  blk-flush: fix invalid BUG_ON in blk_insert_flush
  block: Remove the control of complete cpu from bio.
  block: fix a typo in the blk-cgroup.h file
  block: initialize the bounce pool if high memory may be added later
  block: fix request_queue lifetime handling by making blk_queue_cleanup() properly shutdown
  block: drop @tsk from attempt_plug_merge() and explain sync rules
  block: make get_request[_wait]() fail if queue is dead
  block: reorganize throtl_get_tg() and blk_throtl_bio()
  block: reorganize queue draining
  block: drop unnecessary blk_get/put_queue() in scsi_cmd_ioctl() and blk_get_tg()
  block: pass around REQ_* flags instead of broken down booleans during request alloc/free
  block: move blk_throtl prototypes to block/blk.h
  block: fix genhd refcounting in blkio_policy_parse_and_set()
  ...

Fix up trivial conflicts due to "mddev_t" -> "struct mddev" conversion
and making the request functions be of type "void" instead of "int" in
 - drivers/md/{faulty.c,linear.c,md.c,md.h,multipath.c,raid0.c,raid1.c,raid10.c,raid5.c}
 - drivers/staging/zram/zram_drv.c
2011-11-04 17:06:58 -07:00
Linus Torvalds 092f4c56c1 Merge branch 'akpm' (Andrew's incoming - part two)
Says Andrew:

 "60 patches.  That's good enough for -rc1 I guess.  I have quite a lot
  of detritus to be rechecked, work through maintainers, etc.

 - most of the remains of MM
 - rtc
 - various misc
 - cgroups
 - memcg
 - cpusets
 - procfs
 - ipc
 - rapidio
 - sysctl
 - pps
 - w1
 - drivers/misc
 - aio"

* akpm: (60 commits)
  memcg: replace ss->id_lock with a rwlock
  aio: allocate kiocbs in batches
  drivers/misc/vmw_balloon.c: fix typo in code comment
  drivers/misc/vmw_balloon.c: determine page allocation flag can_sleep outside loop
  w1: disable irqs in critical section
  drivers/w1/w1_int.c: multiple masters used same init_name
  drivers/power/ds2780_battery.c: fix deadlock upon insertion and removal
  drivers/power/ds2780_battery.c: add a nolock function to w1 interface
  drivers/power/ds2780_battery.c: create central point for calling w1 interface
  w1: ds2760 and ds2780, use ida for id and ida_simple_get() to get it
  pps gpio client: add missing dependency
  pps: new client driver using GPIO
  pps: default echo function
  include/linux/dma-mapping.h: add dma_zalloc_coherent()
  sysctl: make CONFIG_SYSCTL_SYSCALL default to n
  sysctl: add support for poll()
  RapidIO: documentation update
  drivers/net/rionet.c: fix ethernet address macros for LE platforms
  RapidIO: fix potential null deref in rio_setup_device()
  RapidIO: add mport driver for Tsi721 bridge
  ...
2011-11-02 16:07:27 -07:00
H Hartley Sweeten 61600f578f mm/page_cgroup.c: quiet sparse noise
warning: symbol 'swap_cgroup_ctrl' was not declared. Should it be static?

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-02 16:07:00 -07:00
Steven Rostedt 4799401fef memcg: Fix race condition in memcg_check_events() with this_cpu usage
Various code in memcontrol.c () calls this_cpu_read() on the calculations
to be done from two different percpu variables, or does an open-coded
read-modify-write on a single percpu variable.

Disable preemption throughout these operations so that the writes go to
the correct palces.

[hannes@cmpxchg.org: added this_cpu to __this_cpu conversion]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-02 16:07:00 -07:00
Johannes Weiner a61ed3cec5 memcg: close race between charge and putback
There is a potential race between a thread charging a page and another
thread putting it back to the LRU list:

  charge:                         putback:
  SetPageCgroupUsed               SetPageLRU
  PageLRU && add to memcg LRU     PageCgroupUsed && add to memcg LRU

The order of setting one flag and checking the other is crucial, otherwise
the charge may observe !PageLRU while the putback observes !PageCgroupUsed
and the page is not linked to the memcg LRU at all.

Global memory pressure may fix this by trying to isolate and putback the
page for reclaim, where that putback would link it to the memcg LRU again.
 Without that, the memory cgroup is undeletable due to a charge whose
physical page can not be found and moved out.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Cc: Ying Han <yinghan@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-02 16:07:00 -07:00
Johannes Weiner 9b272977e3 memcg: skip scanning active lists based on individual size
Reclaim decides to skip scanning an active list when the corresponding
inactive list is above a certain size in comparison to leave the assumed
working set alone while there are still enough reclaim candidates around.

The memcg implementation of comparing those lists instead reports whether
the whole memcg is low on the requested type of inactive pages,
considering all nodes and zones.

This can lead to an oversized active list not being scanned because of the
state of the other lists in the memcg, as well as an active list being
scanned while its corresponding inactive list has enough pages.

Not only is this wrong, it's also a scalability hazard, because the global
memory state over all nodes and zones has to be gathered for each memcg
and zone scanned.

Make these calculations purely based on the size of the two LRU lists
that are actually affected by the outcome of the decision.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-02 16:07:00 -07:00
Igor Mammedov 0a619e5870 memcg: do not expose uninitialized mem_cgroup_per_node to world
If somebody is touching data too early, it might be easier to diagnose a
problem when dereferencing NULL at mem->info.nodeinfo[node] than trying to
understand why mem_cgroup_per_zone is [un|partly]initialized.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-02 16:07:00 -07:00
KAMEZAWA Hiroyuki 715a5ee82a memcg: fix oom schedule_timeout()
Before calling schedule_timeout(), task state should be changed.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-02 16:06:59 -07:00
Raghavendra K T c0ff4b8540 memcg: rename mem variable to memcg
The memcg code sometimes uses "struct mem_cgroup *mem" and sometimes uses
"struct mem_cgroup *memcg".  Rename all mem variables to memcg in source
file.

Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-02 16:06:59 -07:00
Steven Rostedt ff7ee93f47 cgroup/kmemleak: Annotate alloc_page() for cgroup allocations
When the cgroup base was allocated with kmalloc, it was necessary to
annotate the variable with kmemleak_not_leak().  But because it has
recently been changed to be allocated with alloc_page() (which skips
kmemleak checks) causes a warning on boot up.

I was triggering this output:

 allocated 8388608 bytes of page_cgroup
 please try 'cgroup_disable=memory' option if you don't want memory cgroups
 kmemleak: Trying to color unknown object at 0xf5840000 as Grey
 Pid: 0, comm: swapper Not tainted 3.0.0-test #12
 Call Trace:
  [<c17e34e6>] ? printk+0x1d/0x1f^M
  [<c10e2941>] paint_ptr+0x4f/0x78
  [<c178ab57>] kmemleak_not_leak+0x58/0x7d
  [<c108ae9f>] ? __rcu_read_unlock+0x9/0x7d
  [<c1cdb462>] kmemleak_init+0x19d/0x1e9
  [<c1cbf771>] start_kernel+0x346/0x3ec
  [<c1cbf1b4>] ? loglevel+0x18/0x18
  [<c1cbf0aa>] i386_start_kernel+0xaa/0xb0

After a bit of debugging I tracked the object 0xf840000 (and others) down
to the cgroup code.  The change from allocating base with kmalloc to
alloc_page() has the base not calling kmemleak_alloc() which adds the
pointer to the object_tree_root, but kmemleak_not_leak() adds it to the
crt_early_log[] table.  On kmemleak_init(), the entry is found in the
early_log[] but not the object_tree_root, and this error message is
displayed.

If alloc_page() fails then it defaults back to vmalloc() which still uses
the kmemleak_alloc() which makes us still need the kmemleak_not_leak()
call.  The solution is to call the kmemleak_alloc() directly if the
alloc_page() succeeds.

Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-02 16:06:59 -07:00
Andrea Arcangeli 70b50f94f1 mm: thp: tail page refcounting fix
Michel while working on the working set estimation code, noticed that
calling get_page_unless_zero() on a random pfn_to_page(random_pfn)
wasn't safe, if the pfn ended up being a tail page of a transparent
hugepage under splitting by __split_huge_page_refcount().

He then found the problem could also theoretically materialize with
page_cache_get_speculative() during the speculative radix tree lookups
that uses get_page_unless_zero() in SMP if the radix tree page is freed
and reallocated and get_user_pages is called on it before
page_cache_get_speculative has a chance to call get_page_unless_zero().

So the best way to fix the problem is to keep page_tail->_count zero at
all times.  This will guarantee that get_page_unless_zero() can never
succeed on any tail page.  page_tail->_mapcount is guaranteed zero and
is unused for all tail pages of a compound page, so we can simply
account the tail page references there and transfer them to
tail_page->_count in __split_huge_page_refcount() (in addition to the
head_page->_mapcount).

While debugging this s/_count/_mapcount/ change I also noticed get_page is
called by direct-io.c on pages returned by get_user_pages.  That wasn't
entirely safe because the two atomic_inc in get_page weren't atomic.  As
opposed to other get_user_page users like secondary-MMU page fault to
establish the shadow pagetables would never call any superflous get_page
after get_user_page returns.  It's safer to make get_page universally safe
for tail pages and to use get_page_foll() within follow_page (inside
get_user_pages()).  get_page_foll() is safe to do the refcounting for tail
pages without taking any locks because it is run within PT lock protected
critical sections (PT lock for pte and page_table_lock for
pmd_trans_huge).

The standard get_page() as invoked by direct-io instead will now take
the compound_lock but still only for tail pages.  The direct-io paths
are usually I/O bound and the compound_lock is per THP so very
finegrined, so there's no risk of scalability issues with it.  A simple
direct-io benchmarks with all lockdep prove locking and spinlock
debugging infrastructure enabled shows identical performance and no
overhead.  So it's worth it.  Ideally direct-io should stop calling
get_page() on pages returned by get_user_pages().  The spinlock in
get_page() is already optimized away for no-THP builds but doing
get_page() on tail pages returned by GUP is generally a rare operation
and usually only run in I/O paths.

This new refcounting on page_tail->_mapcount in addition to avoiding new
RCU critical sections will also allow the working set estimation code to
work without any further complexity associated to the tail page
refcounting with THP.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: <stable@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-02 16:06:57 -07:00
Miklos Szeredi 6d6b77f163 filesystems: add missing nlink wrappers
Replace direct i_nlink updates with the respective updater function
(inc_nlink, drop_nlink, clear_nlink, inode_dec_link_count).

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2011-11-02 12:53:43 +01:00
Dimitri Sivanich a1cb2c60dd mm/vmstat.c: cache align vm_stat
Avoid false sharing of the vm_stat array.

This was found to adversely affect tmpfs I/O performance.

Tests run on a 640 cpu UV system.

With 120 threads doing parallel writes, each to different tmpfs mounts:
No patch:		~300 MB/sec
With vm_stat alignment:	~430 MB/sec

Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:51 -07:00
Hugh Dickins 3d470fc385 mm: munlock use mapcount to avoid terrible overhead
A process spent 30 minutes exiting, just munlocking the pages of a large
anonymous area that had been alternately mprotected into page-sized vmas:
for every single page there's an anon_vma walk through all the other
little vmas to find the right one.

A general fix to that would be a lot more complicated (use prio_tree on
anon_vma?), but there's one very simple thing we can do to speed up the
common case: if a page to be munlocked is mapped only once, then it is our
vma that it is mapped into, and there's no need whatever to walk through
all the others.

Okay, there is a very remote race in munlock_vma_pages_range(), if between
its follow_page() and lock_page(), another process were to munlock the
same page, then page reclaim remove it from our vma, then another process
mlock it again.  We would find it with page_mapcount 1, yet it's still
mlocked in another process.  But never mind, that's much less likely than
the down_read_trylock() failure which munlocking already tolerates (in
try_to_unmap_one()): in due course page reclaim will discover and move the
page to unevictable instead.

[akpm@linux-foundation.org: add comment]
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:51 -07:00
Hillf Danton 35d8c7ad72 mm/huge_memory: fix typo when updating mmu cache
There are three cases of update_mmu_cache() in the file, and the case in
function collapse_huge_page() has a typo, namely the last parameter used,
which is corrected based on the other two cases.

Due to the define of update_mmu_cache by X86, the only arch that
implements THP currently, the change here has no really crystal point, but
one or two minutes of efforts could be saved for those archs that are
likely to support THP in future.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:51 -07:00
Hillf Danton 0089e4853a mm/huge_memory: fix copying user highpage
The THP copy-on-write handler falls back to regular-sized pages for a huge
page replacement upon allocation failure or if THP has been individually
disabled in the target VMA.  The loop responsible for copying page-sized
chunks accidentally uses multiples of PAGE_SHIFT instead of PAGE_SIZE as
the virtual address arg for copy_user_highpage().

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:50 -07:00
Christoph Lameter df9d6985be mm: do not drain pagevecs for mlockall(MCL_FUTURE)
MCL_FUTURE does not move pages between lru list and draining the LRU per
cpu pagevecs is a nasty activity.  Avoid doing it unecessarily.

Signed-off-by: Christoph Lameter <cl@gentwo.org>
Cc: David Rientjes <rientjes@google.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:50 -07:00
Mel Gorman e0c23279c9 vmscan: abort reclaim/compaction if compaction can proceed
If compaction can proceed, shrink_zones() stops doing any work but its
callers still call shrink_slab() which raises the priority and potentially
sleeps.  This is unnecessary and wasteful so this patch aborts direct
reclaim/compaction entirely if compaction can proceed.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:50 -07:00
Rik van Riel e0887c19b2 vmscan: limit direct reclaim for higher order allocations
When suffering from memory fragmentation due to unfreeable pages, THP page
faults will repeatedly try to compact memory.  Due to the unfreeable
pages, compaction fails.

Needless to say, at that point page reclaim also fails to create free
contiguous 2MB areas.  However, that doesn't stop the current code from
trying, over and over again, and freeing a minimum of 4MB (2UL <<
sc->order pages) at every single invocation.

This resulted in my 12GB system having 2-3GB free memory, a corresponding
amount of used swap and very sluggish response times.

This can be avoided by having the direct reclaim code not reclaim from
zones that already have plenty of free memory available for compaction.

If compaction still fails due to unmovable memory, doing additional
reclaim will only hurt the system, not help.

[jweiner@redhat.com: change comment to explain the order check]
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:50 -07:00
Minchan Kim 21ee9f398b vmscan: add barrier to prevent evictable page in unevictable list
When a race between putback_lru_page() and shmem_lock with lock=0 happens,
progrom execution order is as follows, but clear_bit in processor #1 could
be reordered right before spin_unlock of processor #1.  Then, the page
would be stranded on the unevictable list.

spin_lock
SetPageLRU
spin_unlock
                                clear_bit(AS_UNEVICTABLE)
                                spin_lock
                                if PageLRU()
                                        if !test_bit(AS_UNEVICTABLE)
                                        	move evictable list
smp_mb
if !test_bit(AS_UNEVICTABLE)
        move evictable list
                                spin_unlock

But, pagevec_lookup() in scan_mapping_unevictable_pages() has
rcu_read_[un]lock() so it could protect reordering before reaching
test_bit(AS_UNEVICTABLE) on processor #1 so this problem never happens.
But it's a unexpected side effect and we should solve this problem
properly.

This patch adds a barrier after mapping_clear_unevictable.

I didn't meet this problem but just found during review.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:50 -07:00
H Hartley Sweeten 2f1da64215 mm/huge_memory.c: quiet sparse noise
Quiet the sparse noise:

warning: symbol 'khugepaged_scan' was not declared. Should it be static?
warning: context imbalance in 'khugepaged_scan_mm_slot' - unexpected unlock

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:50 -07:00
H Hartley Sweeten e754d79d35 mm/mempolicy.c: quiet sparse noise
Quiet the spares noise:

warning: symbol 'default_policy' was not declared. Should it be static?

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Stephen Wilson <wilsons@start.ca>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:50 -07:00
H Hartley Sweeten 22d5368a08 mm/thrash.c: quiet sparse noise
Quiet the following sparse noise:

warning: symbol 'swap_token_memcg' was not declared. Should it be static?

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:50 -07:00
H Hartley Sweeten 2d7d3eb2ba mm/memblock.c: quiet sparse noise
Quiet the following sparse noise in this file:

warning: symbol 'memblock_overlaps_region' was not declared. Should it be static?

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers,com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Tomi Valkeinen <tomi.valkeinen@nokia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:50 -07:00
Johannes Weiner 264e56d824 mm: disable user interface to manually rescue unevictable pages
At one point, anonymous pages were supposed to go on the unevictable list
when no swap space was configured, and the idea was to manually rescue
those pages after adding swap and making them evictable again.  But
nowadays, swap-backed pages on the anon LRU list are not scanned without
available swap space anyway, so there is no point in moving them to a
separate list anymore.

The manual rescue could also be used in case pages were stranded on the
unevictable list due to race conditions.  But the code has been around for
a while now and newly discovered bugs should be properly reported and
dealt with instead of relying on such a manual fixup.

In addition to the lack of a usecase, the sysfs interface to rescue pages
from a specific NUMA node has been broken since its introduction, so it's
unlikely that anybody ever relied on that.

This patch removes the functionality behind the sysctl and the
node-interface and emits a one-time warning when somebody tries to access
either of them.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Reported-by: Kautuk Consul <consul.kautuk@gmail.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:49 -07:00
Kautuk Consul 3f380998ae vmscan.c: fix invalid strict_strtoul() check in write_scan_unevictable_node()
write_scan_unevictable_node() checks the value req returned by
strict_strtoul() and returns 1 if req is 0.

However, when strict_strtoul() returns 0, it means successful conversion
of buf to unsigned long.

Due to this, the function was not proceeding to scan the zones for
unevictable pages even though we write a valid value to the
scan_unevictable_pages sys file.

Change this check slightly to check for invalid value in buf as well as 0
value stored in res after successful conversion via strict_strtoul.  In
both cases, we do not perform the scanning of this node's zones.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:49 -07:00
Li Haifeng 4e9dc5df46 mm: fix kunmap_high() comment
Signed-off-by: Li Haifeng <omycle@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:49 -07:00
Kyungmin Park d43a87e68e mm: compaction: make compact_zone_order() static
There's no compact_zone_order() user outside file scope, so make it static.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:49 -07:00
Dean Nelson dd73e85f6d HWPOISON: convert pr_debug()s to pr_info()s
Commit fb46e73520 ("HWPOISON: Convert pr_debugs to pr_info) authored
by Andi Kleen converted a number of pr_debug()s to pr_info()s.

About the same time additional code with pr_debug()s was added by two
other commits 8c6c2ecb44 ("HWPOSION, hugetlb: recover from free hugepage
error when !MF_COUNT_INCREASED") and d950b95882 ("HWPOISON, hugetlb:
soft offlining for hugepage").  And these pr_debug()s failed to get
converted to pr_info()s.

This patch converts them as well.  And does some minor related whitespace
cleanup.

Signed-off-by: Dean Nelson <dnelson@redhat.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:49 -07:00
Kautuk Consul 584cff54e1 mm/mmap.c: eliminate the ret variable from mm_take_all_locks()
The ret variable is really not needed in mm_take_all_locks().

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:49 -07:00
Andrew Morton 20c8c62891 mm-add-comment-explaining-task-state-setting-in-bdi_forker_thread-fix
fiddle wording

Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:49 -07:00
Wanlong Gao 99ef0315f1 ksm: fix the comment of try_to_unmap_one()
try_to_unmap_one() is called by try_to_unmap_ksm(), too.

Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:49 -07:00
Joe Perches de7d2b567d mm/vmalloc.c: report more vmalloc failures
Some vmalloc failure paths do not report OOM conditions.

Add warn_alloc_failed, which also does a dump_stack, to those failure
paths.

This allows more site specific vmalloc failure logging message printks to
be removed.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:48 -07:00
Alex,Shi f0dfcde099 kswapd: assign new_order and new_classzone_idx after wakeup in sleeping
There 2 places to read pgdat in kswapd.  One is return from a successful
balance, another is waked up from kswapd sleeping.  The new_order and
new_classzone_idx represent the balance input order and classzone_idx.

But current new_order and new_classzone_idx are not assigned after
kswapd_try_to_sleep(), that will cause a bug in the following scenario.

1: after a successful balance, kswapd goes to sleep, and new_order = 0;
   new_classzone_idx = __MAX_NR_ZONES - 1;

2: kswapd waked up with order = 3 and classzone_idx = ZONE_NORMAL

3: in the balance_pgdat() running, a new balance wakeup happened with
   order = 5, and classzone_idx = ZONE_NORMAL

4: the first wakeup(order = 3) finished successufly, return order = 3
   but, the new_order is still 0, so, this balancing will be treated as a
   failed balance.  And then the second tighter balancing will be missed.

So, to avoid the above problem, the new_order and new_classzone_idx need
to be assigned for later successful comparison.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Tested-by: Pádraig Brady <P@draigBrady.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:48 -07:00
Jonghwan Choi d1f0ece6cd mm/memblock.c: small function definition fixes
warning: function 'memblock_memory_can_coalesce'
with external linkage has definition.

Signed-off-by: Jonghwan Choi <jhbird.choi@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:48 -07:00
Alex,Shi d2ebd0f6b8 kswapd: avoid unnecessary rebalance after an unsuccessful balancing
In commit 215ddd66 ("mm: vmscan: only read new_classzone_idx from pgdat
when reclaiming successfully") , Mel Gorman said kswapd is better to sleep
after a unsuccessful balancing if there is tighter reclaim request pending
in the balancing.  But in the following scenario, kswapd do something that
is not matched our expectation.  The patch fixes this issue.

1, Read pgdat request A (classzone_idx, order = 3)
2, balance_pgdat()
3, During pgdat, a new pgdat request B (classzone_idx, order = 5) is placed
4, balance_pgdat() returns but failed since returned order = 0
5, pgdat of request A assigned to balance_pgdat(), and do balancing again.
   While the expectation behavior of kswapd should try to sleep.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Tested-by: Pádraig Brady <P@draigBrady.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:48 -07:00
Akinobu Mita 64212ec569 debug-pagealloc: add support for highmem pages
This adds support for highmem pages poisoning and verification to the
debug-pagealloc feature for no-architecture support.

[akpm@linux-foundation.org: remove unneeded preempt_disable/enable]
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:48 -07:00
Joe Perches 3ee9a4f086 mm: neaten warn_alloc_failed
Add __attribute__((format (printf...) to the function to validate format
and arguments.  Use vsprintf extension %pV to avoid any possible message
interleaving.  Coalesce format string.  Convert printks/pr_warning to
pr_warn.

[akpm@linux-foundation.org: use the __printf() macro]
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:48 -07:00
Andrea Arcangeli 37a1c49a91 thp: mremap support and TLB optimization
This adds THP support to mremap (decreases the number of split_huge_page()
calls).

Here are also some benchmarks with a proggy like this:

===
#define _GNU_SOURCE
#include <sys/mman.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/time.h>

#define SIZE (5UL*1024*1024*1024)

int main()
{
        static struct timeval oldstamp, newstamp;
	long diffsec;
	char *p, *p2, *p3, *p4;
	if (posix_memalign((void **)&p, 2*1024*1024, SIZE))
		perror("memalign"), exit(1);
	if (posix_memalign((void **)&p2, 2*1024*1024, SIZE))
		perror("memalign"), exit(1);
	if (posix_memalign((void **)&p3, 2*1024*1024, 4096))
		perror("memalign"), exit(1);

	memset(p, 0xff, SIZE);
	memset(p2, 0xff, SIZE);
	memset(p3, 0x77, 4096);
	gettimeofday(&oldstamp, NULL);
	p4 = mremap(p, SIZE, SIZE, MREMAP_FIXED|MREMAP_MAYMOVE, p3);
	gettimeofday(&newstamp, NULL);
	diffsec = newstamp.tv_sec - oldstamp.tv_sec;
	diffsec = newstamp.tv_usec - oldstamp.tv_usec + 1000000 * diffsec;
	printf("usec %ld\n", diffsec);
	if (p == MAP_FAILED || p4 != p3)
	//if (p == MAP_FAILED)
		perror("mremap"), exit(1);
	if (memcmp(p4, p2, SIZE))
		printf("mremap bug\n"), exit(1);
	printf("ok\n");

	return 0;
}
===

THP on

 Performance counter stats for './largepage13' (3 runs):

          69195836 dTLB-loads                 ( +-   3.546% )  (scaled from 50.30%)
             60708 dTLB-load-misses           ( +-  11.776% )  (scaled from 52.62%)
         676266476 dTLB-stores                ( +-   5.654% )  (scaled from 69.54%)
             29856 dTLB-store-misses          ( +-   4.081% )  (scaled from 89.22%)
        1055848782 iTLB-loads                 ( +-   4.526% )  (scaled from 80.18%)
              8689 iTLB-load-misses           ( +-   2.987% )  (scaled from 58.20%)

        7.314454164  seconds time elapsed   ( +-   0.023% )

THP off

 Performance counter stats for './largepage13' (3 runs):

        1967379311 dTLB-loads                 ( +-   0.506% )  (scaled from 60.59%)
           9238687 dTLB-load-misses           ( +-  22.547% )  (scaled from 61.87%)
        2014239444 dTLB-stores                ( +-   0.692% )  (scaled from 60.40%)
           3312335 dTLB-store-misses          ( +-   7.304% )  (scaled from 67.60%)
        6764372065 iTLB-loads                 ( +-   0.925% )  (scaled from 79.00%)
              8202 iTLB-load-misses           ( +-   0.475% )  (scaled from 70.55%)

        9.693655243  seconds time elapsed   ( +-   0.069% )

grep thp /proc/vmstat
thp_fault_alloc 35849
thp_fault_fallback 0
thp_collapse_alloc 3
thp_collapse_alloc_failed 0
thp_split 0

thp_split 0 confirms no thp split despite plenty of hugepages allocated.

The measurement of only the mremap time (so excluding the 3 long
memset and final long 10GB memory accessing memcmp):

THP on

usec 14824
usec 14862
usec 14859

THP off

usec 256416
usec 255981
usec 255847

With an older kernel without the mremap optimizations (the below patch
optimizes the non THP version too).

THP on

usec 392107
usec 390237
usec 404124

THP off

usec 444294
usec 445237
usec 445820

I guess with a threaded program that sends more IPI on large SMP it'd
create an even larger difference.

All debug options are off except DEBUG_VM to avoid skewing the
results.

The only problem for native 2M mremap like it happens above both the
source and destination address must be 2M aligned or the hugepmd can't be
moved without a split but that is an hardware limitation.

[akpm@linux-foundation.org: coding-style nitpicking]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:48 -07:00
Andrea Arcangeli 7b6efc2bc4 mremap: avoid sending one IPI per page
This replaces ptep_clear_flush() with ptep_get_and_clear() and a single
flush_tlb_range() at the end of the loop, to avoid sending one IPI for
each page.

The mmu_notifier_invalidate_range_start/end section is enlarged
accordingly but this is not going to fundamentally change things.  It was
more by accident that the region under mremap was for the most part still
available for secondary MMUs: the primary MMU was never allowed to
reliably access that region for the duration of the mremap (modulo
trapping SIGSEGV on the old address range which sounds unpractical and
flakey).  If users wants secondary MMUs not to lose access to a large
region under mremap they should reduce the mremap size accordingly in
userland and run multiple calls.  Overall this will run faster so it's
actually going to reduce the time the region is under mremap for the
primary MMU which should provide a net benefit to apps.

For KVM this is a noop because the guest physical memory is never
mremapped, there's just no point it ever moving it while guest runs.  One
target of this optimization is JVM GC (so unrelated to the mmu notifier
logic).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:48 -07:00
Andrea Arcangeli ebed48460b mremap: check for overflow using deltas
Using "- 1" relies on the old_end to be page aligned and PAGE_SIZE > 1,
those are reasonable requirements but the check remains obscure and it
looks more like an off by one error than an overflow check.  This I feel
will improve readability.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:47 -07:00
Sam Ravnborg 6661672053 memblock: add NO_BOOTMEM config symbol
With the NO_BOOTMEM symbol added architectures may now use the following
syntax to tell that they do not need bootmem:

	select NO_BOOTMEM

This is much more convinient than adding a new kconfig symbol which was
otherwise required.

Adding this symbol does not conflict with the architctures that already
define their own symbol.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:47 -07:00
Sam Ravnborg 0a93ebef69 memblock: add memblock_start_of_DRAM()
SPARC32 require access to the start address.  Add a new helper
memblock_start_of_DRAM() to give access to the address of the first
memblock - which contains the lowest address.

The awkward name was chosen to match the already present
memblock_end_of_DRAM().

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Yinghai Lu <yinghai@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:47 -07:00
Mitsuo Hayasaka f5252e009d mm: avoid null pointer access in vm_struct via /proc/vmallocinfo
The /proc/vmallocinfo shows information about vmalloc allocations in
vmlist that is a linklist of vm_struct.  It, however, may access pages
field of vm_struct where a page was not allocated.  This results in a null
pointer access and leads to a kernel panic.

Why this happens: In __vmalloc_node_range() called from vmalloc(), newly
allocated vm_struct is added to vmlist at __get_vm_area_node() and then,
some fields of vm_struct such as nr_pages and pages are set at
__vmalloc_area_node().  In other words, it is added to vmlist before it is
fully initialized.  At the same time, when the /proc/vmallocinfo is read,
it accesses the pages field of vm_struct according to the nr_pages field
at show_numa_info().  Thus, a null pointer access happens.

The patch adds the newly allocated vm_struct to the vmlist *after* it is
fully initialized.  So, it can avoid accessing the pages field with
unallocated page when show_numa_info() is called.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: <stable@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:47 -07:00
Akinobu Mita 8c5fb8eadd mm/debug-pagealloc.c: use memchr_inv
Use newly introduced memchr_inv() for page verification.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:47 -07:00
Akinobu Mita 798248206b lib/string.c: introduce memchr_inv()
memchr_inv() is mainly used to check whether the whole buffer is filled
with just a specified byte.

The function name and prototype are stolen from logfs and the
implementation is from SLUB.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: Joern Engel <joern@logfs.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:47 -07:00
Akinobu Mita 77311139f3 mm/debug-pagealloc.c: use plain __ratelimit() instead of printk_ratelimit()
printk_ratelimit() should not be used, because it shares ratelimiting
state with all other unrelated printk_ratelimit() callsites.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:47 -07:00
Shaohua Li 16fb951237 vmscan: count pages into balanced for zone with good watermark
It's possible a zone watermark is ok when entering the balance_pgdat()
loop, while the zone is within the requested classzone_idx.  Count pages
from this zone into `balanced'.  In this way, we can skip shrinking zones
too much for high order allocation.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:47 -07:00
Mel Gorman 49ea7eb65e mm: vmscan: immediately reclaim end-of-LRU dirty pages when writeback completes
When direct reclaim encounters a dirty page, it gets recycled around the
LRU for another cycle.  This patch marks the page PageReclaim similar to
deactivate_page() so that the page gets reclaimed almost immediately after
the page gets cleaned.  This is to avoid reclaiming clean pages that are
younger than a dirty page encountered at the end of the LRU that might
have been something like a use-once page.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Alex Elder <aelder@sgi.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:47 -07:00
Mel Gorman 92df3a723f mm: vmscan: throttle reclaim if encountering too many dirty pages under writeback
Workloads that are allocating frequently and writing files place a large
number of dirty pages on the LRU.  With use-once logic, it is possible for
them to reach the end of the LRU quickly requiring the reclaimer to scan
more to find clean pages.  Ordinarily, processes that are dirtying memory
will get throttled by dirty balancing but this is a global heuristic and
does not take into account that LRUs are maintained on a per-zone basis.
This can lead to a situation whereby reclaim is scanning heavily, skipping
over a large number of pages under writeback and recycling them around the
LRU consuming CPU.

This patch checks how many of the number of pages isolated from the LRU
were dirty and under writeback.  If a percentage of them under writeback,
the process will be throttled if a backing device or the zone is
congested.  Note that this applies whether it is anonymous or file-backed
pages that are under writeback meaning that swapping is potentially
throttled.  This is intentional due to the fact if the swap device is
congested, scanning more pages and dispatching more IO is not going to
help matters.

The percentage that must be in writeback depends on the priority.  At
default priority, all of them must be dirty.  At DEF_PRIORITY-1, 50% of
them must be, DEF_PRIORITY-2, 25% etc.  i.e.  as pressure increases the
greater the likelihood the process will get throttled to allow the flusher
threads to make some progress.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Alex Elder <aelder@sgi.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:46 -07:00
Mel Gorman f84f6e2b08 mm: vmscan: do not writeback filesystem pages in kswapd except in high priority
It is preferable that no dirty pages are dispatched for cleaning from the
page reclaim path.  At normal priorities, this patch prevents kswapd
writing pages.

However, page reclaim does have a requirement that pages be freed in a
particular zone.  If it is failing to make sufficient progress (reclaiming
< SWAP_CLUSTER_MAX at any priority priority), the priority is raised to
scan more pages.  A priority of DEF_PRIORITY - 3 is considered to be the
point where kswapd is getting into trouble reclaiming pages.  If this
priority is reached, kswapd will dispatch pages for writing.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Alex Elder <aelder@sgi.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:46 -07:00
Mel Gorman a18bba061c mm: vmscan: remove dead code related to lumpy reclaim waiting on pages under writeback
Lumpy reclaim worked with two passes - the first which queued pages for IO
and the second which waited on writeback.  As direct reclaim can no longer
write pages there is some dead code.  This patch removes it but direct
reclaim will continue to wait on pages under writeback while in
synchronous reclaim mode.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Alex Elder <aelder@sgi.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:46 -07:00
Mel Gorman ee72886d8e mm: vmscan: do not writeback filesystem pages in direct reclaim
Testing from the XFS folk revealed that there is still too much I/O from
the end of the LRU in kswapd.  Previously it was considered acceptable by
VM people for a small number of pages to be written back from reclaim with
testing generally showing about 0.3% of pages reclaimed were written back
(higher if memory was low).  That writing back a small number of pages is
ok has been heavily disputed for quite some time and Dave Chinner
explained it well;

	It doesn't have to be a very high number to be a problem. IO
	is orders of magnitude slower than the CPU time it takes to
	flush a page, so the cost of making a bad flush decision is
	very high. And single page writeback from the LRU is almost
	always a bad flush decision.

To complicate matters, filesystems respond very differently to requests
from reclaim according to Christoph Hellwig;

	xfs tries to write it back if the requester is kswapd
	ext4 ignores the request if it's a delayed allocation
	btrfs ignores the request

As a result, each filesystem has different performance characteristics
when under memory pressure and there are many pages being dirtied.  In
some cases, the request is ignored entirely so the VM cannot depend on the
IO being dispatched.

The objective of this series is to reduce writing of filesystem-backed
pages from reclaim, play nicely with writeback that is already in progress
and throttle reclaim appropriately when writeback pages are encountered.
The assumption is that the flushers will always write pages faster than if
reclaim issues the IO.

A secondary goal is to avoid the problem whereby direct reclaim splices
two potentially deep call stacks together.

There is a potential new problem as reclaim has less control over how long
before a page in a particularly zone or container is cleaned and direct
reclaimers depend on kswapd or flusher threads to do the necessary work.
However, as filesystems sometimes ignore direct reclaim requests already,
it is not expected to be a serious issue.

Patch 1 disables writeback of filesystem pages from direct reclaim
	entirely. Anonymous pages are still written.

Patch 2 removes dead code in lumpy reclaim as it is no longer able
	to synchronously write pages. This hurts lumpy reclaim but
	there is an expectation that compaction is used for hugepage
	allocations these days and lumpy reclaim's days are numbered.

Patches 3-4 add warnings to XFS and ext4 if called from
	direct reclaim. With patch 1, this "never happens" and is
	intended to catch regressions in this logic in the future.

Patch 5 disables writeback of filesystem pages from kswapd unless
	the priority is raised to the point where kswapd is considered
	to be in trouble.

Patch 6 throttles reclaimers if too many dirty pages are being
	encountered and the zones or backing devices are congested.

Patch 7 invalidates dirty pages found at the end of the LRU so they
	are reclaimed quickly after being written back rather than
	waiting for a reclaimer to find them

I consider this series to be orthogonal to the writeback work but it is
worth noting that the writeback work affects the viability of patch 8 in
particular.

I tested this on ext4 and xfs using fs_mark, a simple writeback test based
on dd and a micro benchmark that does a streaming write to a large mapping
(exercises use-once LRU logic) followed by streaming writes to a mix of
anonymous and file-backed mappings.  The command line for fs_mark when
botted with 512M looked something like

./fs_mark -d  /tmp/fsmark-2676  -D  100  -N  150  -n  150  -L  25  -t  1  -S0  -s  10485760

The number of files was adjusted depending on the amount of available
memory so that the files created was about 3xRAM.  For multiple threads,
the -d switch is specified multiple times.

The test machine is x86-64 with an older generation of AMD processor with
4 cores.  The underlying storage was 4 disks configured as RAID-0 as this
was the best configuration of storage I had available.  Swap is on a
separate disk.  Dirty ratio was tuned to 40% instead of the default of
20%.

Testing was run with and without monitors to both verify that the patches
were operating as expected and that any performance gain was real and not
due to interference from monitors.

Here is a summary of results based on testing XFS.

512M1P-xfs           Files/s  mean                 32.69 ( 0.00%)     34.44 ( 5.08%)
512M1P-xfs           Elapsed Time fsmark                    51.41     48.29
512M1P-xfs           Elapsed Time simple-wb                114.09    108.61
512M1P-xfs           Elapsed Time mmap-strm                113.46    109.34
512M1P-xfs           Kswapd efficiency fsmark                 62%       63%
512M1P-xfs           Kswapd efficiency simple-wb              56%       61%
512M1P-xfs           Kswapd efficiency mmap-strm              44%       42%
512M-xfs             Files/s  mean                 30.78 ( 0.00%)     35.94 (14.36%)
512M-xfs             Elapsed Time fsmark                    56.08     48.90
512M-xfs             Elapsed Time simple-wb                112.22     98.13
512M-xfs             Elapsed Time mmap-strm                219.15    196.67
512M-xfs             Kswapd efficiency fsmark                 54%       56%
512M-xfs             Kswapd efficiency simple-wb              54%       55%
512M-xfs             Kswapd efficiency mmap-strm              45%       44%
512M-4X-xfs          Files/s  mean                 30.31 ( 0.00%)     33.33 ( 9.06%)
512M-4X-xfs          Elapsed Time fsmark                    63.26     55.88
512M-4X-xfs          Elapsed Time simple-wb                100.90     90.25
512M-4X-xfs          Elapsed Time mmap-strm                261.73    255.38
512M-4X-xfs          Kswapd efficiency fsmark                 49%       50%
512M-4X-xfs          Kswapd efficiency simple-wb              54%       56%
512M-4X-xfs          Kswapd efficiency mmap-strm              37%       36%
512M-16X-xfs         Files/s  mean                 60.89 ( 0.00%)     65.22 ( 6.64%)
512M-16X-xfs         Elapsed Time fsmark                    67.47     58.25
512M-16X-xfs         Elapsed Time simple-wb                103.22     90.89
512M-16X-xfs         Elapsed Time mmap-strm                237.09    198.82
512M-16X-xfs         Kswapd efficiency fsmark                 45%       46%
512M-16X-xfs         Kswapd efficiency simple-wb              53%       55%
512M-16X-xfs         Kswapd efficiency mmap-strm              33%       33%

Up until 512-4X, the FSmark improvements were statistically significant.
For the 4X and 16X tests the results were within standard deviations but
just barely.  The time to completion for all tests is improved which is an
important result.  In general, kswapd efficiency is not affected by
skipping dirty pages.

1024M1P-xfs          Files/s  mean                 39.09 ( 0.00%)     41.15 ( 5.01%)
1024M1P-xfs          Elapsed Time fsmark                    84.14     80.41
1024M1P-xfs          Elapsed Time simple-wb                210.77    184.78
1024M1P-xfs          Elapsed Time mmap-strm                162.00    160.34
1024M1P-xfs          Kswapd efficiency fsmark                 69%       75%
1024M1P-xfs          Kswapd efficiency simple-wb              71%       77%
1024M1P-xfs          Kswapd efficiency mmap-strm              43%       44%
1024M-xfs            Files/s  mean                 35.45 ( 0.00%)     37.00 ( 4.19%)
1024M-xfs            Elapsed Time fsmark                    94.59     91.00
1024M-xfs            Elapsed Time simple-wb                229.84    195.08
1024M-xfs            Elapsed Time mmap-strm                405.38    440.29
1024M-xfs            Kswapd efficiency fsmark                 79%       71%
1024M-xfs            Kswapd efficiency simple-wb              74%       74%
1024M-xfs            Kswapd efficiency mmap-strm              39%       42%
1024M-4X-xfs         Files/s  mean                 32.63 ( 0.00%)     35.05 ( 6.90%)
1024M-4X-xfs         Elapsed Time fsmark                   103.33     97.74
1024M-4X-xfs         Elapsed Time simple-wb                204.48    178.57
1024M-4X-xfs         Elapsed Time mmap-strm                528.38    511.88
1024M-4X-xfs         Kswapd efficiency fsmark                 81%       70%
1024M-4X-xfs         Kswapd efficiency simple-wb              73%       72%
1024M-4X-xfs         Kswapd efficiency mmap-strm              39%       38%
1024M-16X-xfs        Files/s  mean                 42.65 ( 0.00%)     42.97 ( 0.74%)
1024M-16X-xfs        Elapsed Time fsmark                   103.11     99.11
1024M-16X-xfs        Elapsed Time simple-wb                200.83    178.24
1024M-16X-xfs        Elapsed Time mmap-strm                397.35    459.82
1024M-16X-xfs        Kswapd efficiency fsmark                 84%       69%
1024M-16X-xfs        Kswapd efficiency simple-wb              74%       73%
1024M-16X-xfs        Kswapd efficiency mmap-strm              39%       40%

All FSMark tests up to 16X had statistically significant improvements.
For the most part, tests are completing faster with the exception of the
streaming writes to a mixture of anonymous and file-backed mappings which
were slower in two cases

In the cases where the mmap-strm tests were slower, there was more
swapping due to dirty pages being skipped.  The number of additional pages
swapped is almost identical to the fewer number of pages written from
reclaim.  In other words, roughly the same number of pages were reclaimed
but swapping was slower.  As the test is a bit unrealistic and stresses
memory heavily, the small shift is acceptable.

4608M1P-xfs          Files/s  mean                 29.75 ( 0.00%)     30.96 ( 3.91%)
4608M1P-xfs          Elapsed Time fsmark                   512.01    492.15
4608M1P-xfs          Elapsed Time simple-wb                618.18    566.24
4608M1P-xfs          Elapsed Time mmap-strm                488.05    465.07
4608M1P-xfs          Kswapd efficiency fsmark                 93%       86%
4608M1P-xfs          Kswapd efficiency simple-wb              88%       84%
4608M1P-xfs          Kswapd efficiency mmap-strm              46%       45%
4608M-xfs            Files/s  mean                 27.60 ( 0.00%)     28.85 ( 4.33%)
4608M-xfs            Elapsed Time fsmark                   555.96    532.34
4608M-xfs            Elapsed Time simple-wb                659.72    571.85
4608M-xfs            Elapsed Time mmap-strm               1082.57   1146.38
4608M-xfs            Kswapd efficiency fsmark                 89%       91%
4608M-xfs            Kswapd efficiency simple-wb              88%       82%
4608M-xfs            Kswapd efficiency mmap-strm              48%       46%
4608M-4X-xfs         Files/s  mean                 26.00 ( 0.00%)     27.47 ( 5.35%)
4608M-4X-xfs         Elapsed Time fsmark                   592.91    564.00
4608M-4X-xfs         Elapsed Time simple-wb                616.65    575.07
4608M-4X-xfs         Elapsed Time mmap-strm               1773.02   1631.53
4608M-4X-xfs         Kswapd efficiency fsmark                 90%       94%
4608M-4X-xfs         Kswapd efficiency simple-wb              87%       82%
4608M-4X-xfs         Kswapd efficiency mmap-strm              43%       43%
4608M-16X-xfs        Files/s  mean                 26.07 ( 0.00%)     26.42 ( 1.32%)
4608M-16X-xfs        Elapsed Time fsmark                   602.69    585.78
4608M-16X-xfs        Elapsed Time simple-wb                606.60    573.81
4608M-16X-xfs        Elapsed Time mmap-strm               1549.75   1441.86
4608M-16X-xfs        Kswapd efficiency fsmark                 98%       98%
4608M-16X-xfs        Kswapd efficiency simple-wb              88%       82%
4608M-16X-xfs        Kswapd efficiency mmap-strm              44%       42%

Unlike the other tests, the fsmark results are not statistically
significant but the min and max times are both improved and for the most
part, tests completed faster.

There are other indications that this is an improvement as well.  For
example, in the vast majority of cases, there were fewer pages scanned by
direct reclaim implying in many cases that stalls due to direct reclaim
are reduced.  KSwapd is scanning more due to skipping dirty pages which is
unfortunate but the CPU usage is still acceptable

In an earlier set of tests, I used blktrace and in almost all cases
throughput throughout the entire test was higher.  However, I ended up
discarding those results as recording blktrace data was too heavy for my
liking.

On a laptop, I plugged in a USB stick and ran a similar tests of tests
using it as backing storage.  A desktop environment was running and for
the entire duration of the tests, firefox and gnome terminal were
launching and exiting to vaguely simulate a user.

1024M-xfs            Files/s  mean               0.41 ( 0.00%)        0.44 ( 6.82%)
1024M-xfs            Elapsed Time fsmark               2053.52   1641.03
1024M-xfs            Elapsed Time simple-wb            1229.53    768.05
1024M-xfs            Elapsed Time mmap-strm            4126.44   4597.03
1024M-xfs            Kswapd efficiency fsmark              84%       85%
1024M-xfs            Kswapd efficiency simple-wb           92%       81%
1024M-xfs            Kswapd efficiency mmap-strm           60%       51%
1024M-xfs            Avg wait ms fsmark                5404.53     4473.87
1024M-xfs            Avg wait ms simple-wb             2541.35     1453.54
1024M-xfs            Avg wait ms mmap-strm             3400.25     3852.53

The mmap-strm results were hurt because firefox launching had a tendency
to push the test out of memory.  On the postive side, firefox launched
marginally faster with the patches applied.  Time to completion for many
tests was faster but more importantly - the "Avg wait" time as measured by
iostat was far lower implying the system would be more responsive.  It was
also the case that "Avg wait ms" on the root filesystem was lower.  I
tested it manually and while the system felt slightly more responsive
while copying data to a USB stick, it was marginal enough that it could be
my imagination.

This patch: do not writeback filesystem pages in direct reclaim.

When kswapd is failing to keep zones above the min watermark, a process
will enter direct reclaim in the same manner kswapd does.  If a dirty page
is encountered during the scan, this page is written to backing storage
using mapping->writepage.

This causes two problems.  First, it can result in very deep call stacks,
particularly if the target storage or filesystem are complex.  Some
filesystems ignore write requests from direct reclaim as a result.  The
second is that a single-page flush is inefficient in terms of IO.  While
there is an expectation that the elevator will merge requests, this does
not always happen.  Quoting Christoph Hellwig;

	The elevator has a relatively small window it can operate on,
	and can never fix up a bad large scale writeback pattern.

This patch prevents direct reclaim writing back filesystem pages by
checking if current is kswapd.  Anonymous pages are still written to swap
as there is not the equivalent of a flusher thread for anonymous pages.
If the dirty pages cannot be written back, they are placed back on the LRU
lists.  There is now a direct dependency on dirty page balancing to
prevent too many pages in the system being dirtied which would prevent
reclaim making forward progress.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Alex Elder <aelder@sgi.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:46 -07:00
Johannes Weiner f11c0ca501 mm: vmscan: drop nr_force_scan[] from get_scan_count
The nr_force_scan[] tuple holds the effective scan numbers for anon and
file pages in case the situation called for a forced scan and the
regularly calculated scan numbers turned out zero.

However, the effective scan number can always be assumed to be
SWAP_CLUSTER_MAX right before the division into anon and file.  The
numerators and denominator are properly set up for all cases, be it force
scan for just file, just anon, or both, to do the right thing.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:46 -07:00
Dave Jones 4f31888c10 mm: output a list of loaded modules when we hit bad_page()
When we get a bad_page bug report, it's useful to see what modules the
user had loaded.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:45 -07:00
David Rientjes 43362a4977 oom: fix race while temporarily setting current's oom_score_adj
test_set_oom_score_adj() was introduced in 72788c3856 ("oom: replace
PF_OOM_ORIGIN with toggling oom_score_adj") to temporarily elevate
current's oom_score_adj for ksm and swapoff without requiring an
additional per-process flag.

Using that function to both set oom_score_adj to OOM_SCORE_ADJ_MAX and
then reinstate the previous value is racy since it's possible that
userspace can set the value to something else itself before the old value
is reinstated.  That results in userspace setting current's oom_score_adj
to a different value and then the kernel immediately setting it back to
its previous value without notification.

To fix this, a new compare_swap_oom_score_adj() function is introduced
with the same semantics as the compare and swap CAS instruction, or
CMPXCHG on x86.  It is used to reinstate the previous value of
oom_score_adj if and only if the present value is the same as the old
value.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ying Han <yinghan@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:45 -07:00
David Rientjes c9f01245b6 oom: remove oom_disable_count
This removes mm->oom_disable_count entirely since it's unnecessary and
currently buggy.  The counter was intended to be per-process but it's
currently decremented in the exit path for each thread that exits, causing
it to underflow.

The count was originally intended to prevent oom killing threads that
share memory with threads that cannot be killed since it doesn't lead to
future memory freeing.  The counter could be fixed to represent all
threads sharing the same mm, but it's better to remove the count since:

 - it is possible that the OOM_DISABLE thread sharing memory with the
   victim is waiting on that thread to exit and will actually cause
   future memory freeing, and

 - there is no guarantee that a thread is disabled from oom killing just
   because another thread sharing its mm is oom disabled.

Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Ying Han <yinghan@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:45 -07:00
David Rientjes 7b0d44fa49 oom: avoid killing kthreads if they assume the oom killed thread's mm
After selecting a task to kill, the oom killer iterates all processes and
kills all other threads that share the same mm_struct in different thread
groups.  It would not otherwise be helpful to kill a thread if its memory
would not be subsequently freed.

A kernel thread, however, may assume a user thread's mm by using
use_mm().  This is only temporary and should not result in sending a
SIGKILL to that kthread.

This patch ensures that only user threads and not kthreads are sent a
SIGKILL if they share the same mm_struct as the oom killed task.

Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:45 -07:00
David Rientjes f660daac47 oom: thaw threads if oom killed thread is frozen before deferring
If a thread has been oom killed and is frozen, thaw it before returning to
the page allocator.  Otherwise, it can stay frozen indefinitely and no
memory will be freed.

Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:45 -07:00
Johannes Weiner d08c429b06 mm/page-writeback.c: document bdi_min_ratio
Looks like someone got distracted after adding the comment characters.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:45 -07:00
Shaohua Li 3da367c3e5 vmscan: add block plug for page reclaim
per-task block plug can reduce block queue lock contention and increase
request merge.  Currently page reclaim doesn't support it.  I originally
thought page reclaim doesn't need it, because kswapd thread count is
limited and file cache write is done at flusher mostly.

When I test a workload with heavy swap in a 4-node machine, each CPU is
doing direct page reclaim and swap.  This causes block queue lock
contention.  In my test, without below patch, the CPU utilization is about
2% ~ 7%.  With the patch, the CPU utilization is about 1% ~ 3%.  Disk
throughput isn't changed.  This should improve normal kswapd write and
file cache write too (increase request merge for example), but might not
be so obvious as I explain above.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:45 -07:00
Minchan Kim 0dabec93de mm: migration: clean up unmap_and_move()
unmap_and_move() is one a big messy function.  Clean it up.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:45 -07:00
Minchan Kim f80c067361 mm: zone_reclaim: make isolate_lru_page() filter-aware
In __zone_reclaim case, we don't want to shrink mapped page.  Nonetheless,
we have isolated mapped page and re-add it into LRU's head.  It's
unnecessary CPU overhead and makes LRU churning.

Of course, when we isolate the page, the page might be mapped but when we
try to migrate the page, the page would be not mapped.  So it could be
migrated.  But race is rare and although it happens, it's no big deal.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:44 -07:00
Minchan Kim 39deaf8585 mm: compaction: make isolate_lru_page() filter-aware
In async mode, compaction doesn't migrate dirty or writeback pages.  So,
it's meaningless to pick the page and re-add it to lru list.

Of course, when we isolate the page in compaction, the page might be dirty
or writeback but when we try to migrate the page, the page would be not
dirty, writeback.  So it could be migrated.  But it's very unlikely as
isolate and migration cycle is much faster than writeout.

So, this patch helps cpu overhead and prevent unnecessary LRU churning.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:44 -07:00
Minchan Kim 4356f21d09 mm: change isolate mode from #define to bitwise type
Change ISOLATE_XXX macro with bitwise isolate_mode_t type.  Normally,
macro isn't recommended as it's type-unsafe and making debugging harder as
symbol cannot be passed throught to the debugger.

Quote from Johannes
" Hmm, it would probably be cleaner to fully convert the isolation mode
into independent flags.  INACTIVE, ACTIVE, BOTH is currently a
tri-state among flags, which is a bit ugly."

This patch moves isolate mode from swap.h to mmzone.h by memcontrol.h

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:44 -07:00
Minchan Kim b9e84ac153 mm: compaction: trivial clean up in acct_isolated()
acct_isolated of compaction uses page_lru_base_type which returns only
base type of LRU list so it never returns LRU_ACTIVE_ANON or
LRU_ACTIVE_FILE.  In addtion, cc->nr_[anon|file] is used in only
acct_isolated so it doesn't have fields in conpact_control.

This patch removes fields from compact_control and makes clear function of
acct_issolated which counts the number of anon|file pages isolated.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:44 -07:00
Christopher Yeoh fcf634098c Cross Memory Attach
The basic idea behind cross memory attach is to allow MPI programs doing
intra-node communication to do a single copy of the message rather than a
double copy of the message via shared memory.

The following patch attempts to achieve this by allowing a destination
process, given an address and size from a source process, to copy memory
directly from the source process into its own address space via a system
call.  There is also a symmetrical ability to copy from the current
process's address space into a destination process's address space.

- Use of /proc/pid/mem has been considered, but there are issues with
  using it:
  - Does not allow for specifying iovecs for both src and dest, assuming
    preadv or pwritev was implemented either the area read from or
  written to would need to be contiguous.
  - Currently mem_read allows only processes who are currently
  ptrace'ing the target and are still able to ptrace the target to read
  from the target. This check could possibly be moved to the open call,
  but its not clear exactly what race this restriction is stopping
  (reason  appears to have been lost)
  - Having to send the fd of /proc/self/mem via SCM_RIGHTS on unix
  domain socket is a bit ugly from a userspace point of view,
  especially when you may have hundreds if not (eventually) thousands
  of processes  that all need to do this with each other
  - Doesn't allow for some future use of the interface we would like to
  consider adding in the future (see below)
  - Interestingly reading from /proc/pid/mem currently actually
  involves two copies! (But this could be fixed pretty easily)

As mentioned previously use of vmsplice instead was considered, but has
problems.  Since you need the reader and writer working co-operatively if
the pipe is not drained then you block.  Which requires some wrapping to
do non blocking on the send side or polling on the receive.  In all to all
communication it requires ordering otherwise you can deadlock.  And in the
example of many MPI tasks writing to one MPI task vmsplice serialises the
copying.

There are some cases of MPI collectives where even a single copy interface
does not get us the performance gain we could.  For example in an
MPI_Reduce rather than copy the data from the source we would like to
instead use it directly in a mathops (say the reduce is doing a sum) as
this would save us doing a copy.  We don't need to keep a copy of the data
from the source.  I haven't implemented this, but I think this interface
could in the future do all this through the use of the flags - eg could
specify the math operation and type and the kernel rather than just
copying the data would apply the specified operation between the source
and destination and store it in the destination.

Although we don't have a "second user" of the interface (though I've had
some nibbles from people who may be interested in using it for intra
process messaging which is not MPI).  This interface is something which
hardware vendors are already doing for their custom drivers to implement
fast local communication.  And so in addition to this being useful for
OpenMPI it would mean the driver maintainers don't have to fix things up
when the mm changes.

There was some discussion about how much faster a true zero copy would
go. Here's a link back to the email with some testing I did on that:

http://marc.info/?l=linux-mm&m=130105930902915&w=2

There is a basic man page for the proposed interface here:

http://ozlabs.org/~cyeoh/cma/process_vm_readv.txt

This has been implemented for x86 and powerpc, other architecture should
mainly (I think) just need to add syscall numbers for the process_vm_readv
and process_vm_writev. There are 32 bit compatibility versions for
64-bit kernels.

For arch maintainers there are some simple tests to be able to quickly
verify that the syscalls are working correctly here:

http://ozlabs.org/~cyeoh/cma/cma-test-20110718.tgz

Signed-off-by: Chris Yeoh <yeohc@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: <linux-man@vger.kernel.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:44 -07:00
Paul Gortmaker 7c77509c54 mm: fix implicit stat.h usage in dmapool.c
The removal of the implicitly everywhere module.h and its child includes
will reveal this implicit stat.h usage:

mm/dmapool.c:108: error: ‘S_IRUGO’ undeclared here (not in a function)

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-10-31 09:20:12 -04:00
Paul Gortmaker b95f1b31b7 mm: Map most files to use export.h instead of module.h
The files changed within are only using the EXPORT_SYMBOL
macro variants.  They are not using core modular infrastructure
and hence don't need module.h but only the export.h header.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-10-31 09:20:12 -04:00
Paul Gortmaker b9e15bafdf mm: Add export.h for EXPORT_SYMBOL to active symbol exporters
These files were getting <linux/module.h> via an implicit include
path, but we want to crush those out of existence since they cost
time during compiles of processing thousands of lines of headers
for no reason.  Give them the lightweight header that just contains
the EXPORT_SYMBOL infrastructure.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-10-31 09:20:12 -04:00
Paul Gortmaker e25934a517 mm: delete various needless include <linux/module.h>
There is nothing modular in these files, and no reason to drag
in all the 357 headers that module.h brings with it, since
it just slows down compiles.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-10-31 09:20:11 -04:00
Curt Wohlgemuth 0e175a1835 writeback: Add a 'reason' to wb_writeback_work
This creates a new 'reason' field in a wb_writeback_work
structure, which unambiguously identifies who initiates
writeback activity.  A 'wb_reason' enumeration has been
added to writeback.h, to enumerate the possible reasons.

The 'writeback_work_class' and tracepoint event class and
'writeback_queue_io' tracepoints are updated to include the
symbolic 'reason' in all trace events.

And the 'writeback_inodes_sbXXX' family of routines has had
a wb_stats parameter added to them, so callers can specify
why writeback is being started.

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-31 00:33:36 +08:00
Wu Fengguang ece13ac31b writeback: trace event balance_dirty_pages
Useful for analyzing the dynamics of the throttling algorithms and
debugging user reported problems.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-31 00:29:38 +08:00
Wu Fengguang b48c104d22 writeback: trace event bdi_dirty_ratelimit
It helps understand how various throttle bandwidths are updated.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-31 00:29:21 +08:00
Linus Torvalds f362f98e7c Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue: (21 commits)
  leases: fix write-open/read-lease race
  nfs: drop unnecessary locking in llseek
  ext4: replace cut'n'pasted llseek code with generic_file_llseek_size
  vfs: add generic_file_llseek_size
  vfs: do (nearly) lockless generic_file_llseek
  direct-io: merge direct_io_walker into __blockdev_direct_IO
  direct-io: inline the complete submission path
  direct-io: separate map_bh from dio
  direct-io: use a slab cache for struct dio
  direct-io: rearrange fields in dio/dio_submit to avoid holes
  direct-io: fix a wrong comment
  direct-io: separate fields only used in the submission path from struct dio
  vfs: fix spinning prevention in prune_icache_sb
  vfs: add a comment to inode_permission()
  vfs: pass all mask flags check_acl and posix_acl_permission
  vfs: add hex format for MAY_* flag values
  vfs: indicate that the permission functions take all the MAY_* flags
  compat: sync compat_stats with statfs.
  vfs: add "device" tag to /proc/self/mountstats
  cleanup: vfs: small comment fix for block_invalidatepage
  ...

Fix up trivial conflict in fs/gfs2/file.c (llseek changes)
2011-10-28 10:49:34 -07:00
Jeff Layton 39be79c16f vfs: iov_iter: have iov_iter_advance decrement nr_segs appropriately
Currently, when you call iov_iter_advance, then the pointer to the iovec
array can be incremented, but it does not decrement the nr_segs value in
the iov_iter struct. The result is a iov_iter struct with a nr_segs
value that goes beyond the end of the array.

While I'm not aware of anything that's specifically broken by this, it
seems odd and a bit dangerous not to decrement that value. If someone
were to trust the nr_segs value to be correct, then they could end up
walking off the end of the array.

Changing this might also provide some micro-optimization when dealing
with the last iovec in an array. Many of the other routines that deal
with iov_iter have optimized codepaths when nr_segs == 1.

Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
2011-10-28 13:55:08 +02:00
Pekka Enberg e182a345d4 Merge branches 'slab/next' and 'slub/partial' into slab/for-linus 2011-10-26 18:09:12 +03:00
Linus Torvalds 59e5253417 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (59 commits)
  MAINTAINERS: linux-m32r is moderated for non-subscribers
  linux@lists.openrisc.net is moderated for non-subscribers
  Drop default from "DM365 codec select" choice
  parisc: Kconfig: cleanup Kernel page size default
  Kconfig: remove redundant CONFIG_ prefix on two symbols
  cris: remove arch/cris/arch-v32/lib/nand_init.S
  microblaze: add missing CONFIG_ prefixes
  h8300: drop puzzling Kconfig dependencies
  MAINTAINERS: microblaze-uclinux@itee.uq.edu.au is moderated for non-subscribers
  tty: drop superfluous dependency in Kconfig
  ARM: mxc: fix Kconfig typo 'i.MX51'
  Fix file references in Kconfig files
  aic7xxx: fix Kconfig references to READMEs
  Fix file references in drivers/ide/
  thinkpad_acpi: Fix printk typo 'bluestooth'
  bcmring: drop commented out line in Kconfig
  btmrvl_sdio: fix typo 'btmrvl_sdio_sd6888'
  doc: raw1394: Trivial typo fix
  CIFS: Don't free volume_info->UNC until we are entirely done with it.
  treewide: Correct spelling of successfully in comments
  ...
2011-10-25 12:11:02 +02:00
Linus Torvalds 36b8d186e6 Merge branch 'next' of git://selinuxproject.org/~jmorris/linux-security
* 'next' of git://selinuxproject.org/~jmorris/linux-security: (95 commits)
  TOMOYO: Fix incomplete read after seek.
  Smack: allow to access /smack/access as normal user
  TOMOYO: Fix unused kernel config option.
  Smack: fix: invalid length set for the result of /smack/access
  Smack: compilation fix
  Smack: fix for /smack/access output, use string instead of byte
  Smack: domain transition protections (v3)
  Smack: Provide information for UDS getsockopt(SO_PEERCRED)
  Smack: Clean up comments
  Smack: Repair processing of fcntl
  Smack: Rule list lookup performance
  Smack: check permissions from user space (v2)
  TOMOYO: Fix quota and garbage collector.
  TOMOYO: Remove redundant tasklist_lock.
  TOMOYO: Fix domain transition failure warning.
  TOMOYO: Remove tomoyo_policy_memory_lock spinlock.
  TOMOYO: Simplify garbage collector.
  TOMOYO: Fix make namespacecheck warnings.
  target: check hex2bin result
  encrypted-keys: check hex2bin result
  ...
2011-10-25 09:45:31 +02:00
David Vrabel 3bcfeaf93f block: initialize the bounce pool if high memory may be added later
init_emergency_pool() does not create the page pool for bouncing block
requests if the current count of high pages is zero.  If high memory
may be added later (either via memory hotplug or a balloon driver in a
virtualized system) then a oops occurs if a request with a high page
need bouncing because the pool does not exist.

So, always create the pool if memory hotplug is enabled and change the
test so it's valid even if all high pages are currently in the balloon
(the balloon drivers adjust totalhigh_pages but not max_pfn).

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-10-20 21:24:30 +02:00
Hugh Dickins 486cf46f3f mm: fix race between mremap and removing migration entry
I don't usually pay much attention to the stale "? " addresses in
stack backtraces, but this lucky report from Pawel Sikora hints that
mremap's move_ptes() has inadequate locking against page migration.

 3.0 BUG_ON(!PageLocked(p)) in migration_entry_to_page():
 kernel BUG at include/linux/swapops.h:105!
 RIP: 0010:[<ffffffff81127b76>]  [<ffffffff81127b76>]
                       migration_entry_wait+0x156/0x160
  [<ffffffff811016a1>] handle_pte_fault+0xae1/0xaf0
  [<ffffffff810feee2>] ? __pte_alloc+0x42/0x120
  [<ffffffff8112c26b>] ? do_huge_pmd_anonymous_page+0xab/0x310
  [<ffffffff81102a31>] handle_mm_fault+0x181/0x310
  [<ffffffff81106097>] ? vma_adjust+0x537/0x570
  [<ffffffff81424bed>] do_page_fault+0x11d/0x4e0
  [<ffffffff81109a05>] ? do_mremap+0x2d5/0x570
  [<ffffffff81421d5f>] page_fault+0x1f/0x30

mremap's down_write of mmap_sem, together with i_mmap_mutex or lock,
and pagetable locks, were good enough before page migration (with its
requirement that every migration entry be found) came in, and enough
while migration always held mmap_sem; but not enough nowadays, when
there's memory hotremove and compaction.

The danger is that move_ptes() lets a migration entry dodge around
behind remove_migration_pte()'s back, so it's in the old location when
looking at the new, then in the new location when looking at the old.

Either mremap's move_ptes() must additionally take anon_vma lock(), or
migration's remove_migration_pte() must stop peeking for is_swap_entry()
before it takes pagetable lock.

Consensus chooses the latter: we prefer to add overhead to migration
than to mremapping, which gets used by JVMs and by exec stack setup.

Reported-and-tested-by: Paweł Sikora <pluto@agmk.net>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-19 23:42:58 -07:00
Wu Fengguang 50657fc4df writeback: fix ppc compile warnings on do_div(long long, unsigned long)
Fix powerpc compile warnings

mm/page-writeback.c: In function 'bdi_position_ratio':
mm/page-writeback.c:622:3: warning: comparison of distinct pointer types lacks a cast [enabled by default]
page-writeback.c:635:4: warning: comparison of distinct pointer types lacks a cast [enabled by default]

Also fix gcc "uninitialized var" warnings.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-11 17:45:24 +08:00
Wu Fengguang 8927f66c4e writeback: dirty position control - bdi reserve area
Keep a minimal pool of dirty pages for each bdi, so that the disk IO
queues won't underrun. Also gently increase a small bdi_thresh to avoid
it stuck in 0 for some light dirtied bdi.

It's particularly useful for JBOD and small memory system.

It may result in (pos_ratio > 1) at the setpoint and push the dirty
pages high. This is more or less intended because the bdi is in the
danger of IO queue underflow.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:58 +08:00
Wu Fengguang 57fc978cfb writeback: control dirty pause time
The dirty pause time shall ultimately be controlled by adjusting
nr_dirtied_pause, since there is relationship

	pause = pages_dirtied / task_ratelimit

Assuming

	pages_dirtied ~= nr_dirtied_pause
	task_ratelimit ~= dirty_ratelimit

We get

	nr_dirtied_pause ~= dirty_ratelimit * desired_pause

Here dirty_ratelimit is preferred over task_ratelimit because it's
more stable.

It's also important to limit possible large transitional errors:

- bw is changing quickly
- pages_dirtied << nr_dirtied_pause on entering dirty exceeded area
- pages_dirtied >> nr_dirtied_pause on btrfs (to be improved by a
  separate fix, but still expect non-trivial errors)

So we end up using the above formula inside clamp_val().

The best test case for this code is to run 100 "dd bs=4M" tasks on
btrfs and check its pause time distribution.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:58 +08:00
Wu Fengguang c8462cc9de writeback: limit max dirty pause time
Apply two policies to scale down the max pause time for

1) small number of concurrent dirtiers
2) small memory system (comparing to storage bandwidth)

MAX_PAUSE=200ms may only be suitable for high end servers with lots of
concurrent dirtiers, where the large pause time can reduce much overheads.

Otherwise, smaller pause time is desirable whenever possible, so as to
get good responsiveness and smooth user experiences. It's actually
required for good disk utilization in the case when all the dirty pages
can be synced to disk within MAX_PAUSE=200ms.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:57 +08:00
Wu Fengguang 143dfe8611 writeback: IO-less balance_dirty_pages()
As proposed by Chris, Dave and Jan, don't start foreground writeback IO
inside balance_dirty_pages(). Instead, simply let it idle sleep for some
time to throttle the dirtying task. In the mean while, kick off the
per-bdi flusher thread to do background writeback IO.

RATIONALS
=========

- disk seeks on concurrent writeback of multiple inodes (Dave Chinner)

  If every thread doing writes and being throttled start foreground
  writeback, it leads to N IO submitters from at least N different
  inodes at the same time, end up with N different sets of IO being
  issued with potentially zero locality to each other, resulting in
  much lower elevator sort/merge efficiency and hence we seek the disk
  all over the place to service the different sets of IO.
  OTOH, if there is only one submission thread, it doesn't jump between
  inodes in the same way when congestion clears - it keeps writing to
  the same inode, resulting in large related chunks of sequential IOs
  being issued to the disk. This is more efficient than the above
  foreground writeback because the elevator works better and the disk
  seeks less.

- lock contention and cache bouncing on concurrent IO submitters (Dave Chinner)

  With this patchset, the fs_mark benchmark on a 12-drive software RAID0 goes
  from CPU bound to IO bound, freeing "3-4 CPUs worth of spinlock contention".

  * "CPU usage has dropped by ~55%", "it certainly appears that most of
    the CPU time saving comes from the removal of contention on the
    inode_wb_list_lock" (IMHO at least 10% comes from the reduction of
    cacheline bouncing, because the new code is able to call much less
    frequently into balance_dirty_pages() and hence access the global
    page states)

  * the user space "App overhead" is reduced by 20%, by avoiding the
    cacheline pollution by the complex writeback code path

  * "for a ~5% throughput reduction", "the number of write IOs have
    dropped by ~25%", and the elapsed time reduced from 41:42.17 to
    40:53.23.

  * On a simple test of 100 dd, it reduces the CPU %system time from 30% to 3%,
    and improves IO throughput from 38MB/s to 42MB/s.

- IO size too small for fast arrays and too large for slow USB sticks

  The write_chunk used by current balance_dirty_pages() cannot be
  directly set to some large value (eg. 128MB) for better IO efficiency.
  Because it could lead to more than 1 second user perceivable stalls.
  Even the current 4MB write size may be too large for slow USB sticks.
  The fact that balance_dirty_pages() starts IO on itself couples the
  IO size to wait time, which makes it hard to do suitable IO size while
  keeping the wait time under control.

  Now it's possible to increase writeback chunk size proportional to the
  disk bandwidth. In a simple test of 50 dd's on XFS, 1-HDD, 3GB ram,
  the larger writeback size dramatically reduces the seek count to 1/10
  (far beyond my expectation) and improves the write throughput by 24%.

- long block time in balance_dirty_pages() hurts desktop responsiveness

  Many of us may have the experience: it often takes a couple of seconds
  or even long time to stop a heavy writing dd/cp/tar command with
  Ctrl-C or "kill -9".

- IO pipeline broken by bumpy write() progress

  There are a broad class of "loop {read(buf); write(buf);}" applications
  whose read() pipeline will be under-utilized or even come to a stop if
  the write()s have long latencies _or_ don't progress in a constant rate.
  The current threshold based throttling inherently transfers the large
  low level IO completion fluctuations to bumpy application write()s,
  and further deteriorates with increasing number of dirtiers and/or bdi's.

  For example, when doing 50 dd's + 1 remote rsync to an XFS partition,
  the rsync progresses very bumpy in legacy kernel, and throughput is
  improved by 67% by this patchset. (plus the larger write chunk size,
  it will be 93% speedup).

  The new rate based throttling can support 1000+ dd's with excellent
  smoothness, low latency and low overheads.

For the above reasons, it's much better to do IO-less and low latency
pauses in balance_dirty_pages().

Jan Kara, Dave Chinner and me explored the scheme to let
balance_dirty_pages() wait for enough writeback IO completions to
safeguard the dirty limit. However it's found to have two problems:

- in large NUMA systems, the per-cpu counters may have big accounting
  errors, leading to big throttle wait time and jitters.

- NFS may kill large amount of unstable pages with one single COMMIT.
  Because NFS server serves COMMIT with expensive fsync() IOs, it is
  desirable to delay and reduce the number of COMMITs. So it's not
  likely to optimize away such kind of bursty IO completions, and the
  resulted large (and tiny) stall times in IO completion based throttling.

So here is a pause time oriented approach, which tries to control the
pause time in each balance_dirty_pages() invocations, by controlling
the number of pages dirtied before calling balance_dirty_pages(), for
smooth and efficient dirty throttling:

- avoid useless (eg. zero pause time) balance_dirty_pages() calls
- avoid too small pause time (less than   4ms, which burns CPU power)
- avoid too large pause time (more than 200ms, which hurts responsiveness)
- avoid big fluctuations of pause times

It can control pause times at will. The default policy (in a followup
patch) will be to do ~10ms pauses in 1-dd case, and increase to ~100ms
in 1000-dd case.

BEHAVIOR CHANGE
===============

(1) dirty threshold

Users will notice that the applications will get throttled once crossing
the global (background + dirty)/2=15% threshold, and then balanced around
17.5%. Before patch, the behavior is to just throttle it at 20% dirtyable
memory in 1-dd case.

Since the task will be soft throttled earlier than before, it may be
perceived by end users as performance "slow down" if his application
happens to dirty more than 15% dirtyable memory.

(2) smoothness/responsiveness

Users will notice a more responsive system during heavy writeback.
"killall dd" will take effect instantly.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:57 +08:00
Wu Fengguang 9d823e8f6b writeback: per task dirty rate limit
Add two fields to task_struct.

1) account dirtied pages in the individual tasks, for accuracy
2) per-task balance_dirty_pages() call intervals, for flexibility

The balance_dirty_pages() call interval (ie. nr_dirtied_pause) will
scale near-sqrt to the safety gap between dirty pages and threshold.

The main problem of per-task nr_dirtied is, if 1k+ tasks start dirtying
pages at exactly the same time, each task will be assigned a large
initial nr_dirtied_pause, so that the dirty threshold will be exceeded
long before each task reached its nr_dirtied_pause and hence call
balance_dirty_pages().

The solution is to watch for the number of pages dirtied on each CPU in
between the calls into balance_dirty_pages(). If it exceeds ratelimit_pages
(3% dirty threshold), force call balance_dirty_pages() for a chance to
set bdi->dirty_exceeded. In normal situations, this safeguarding
condition is not expected to trigger at all.

On the sqrt in dirty_poll_interval():

It will serve as an initial guess when dirty pages are still in the
freerun area.

When dirty pages are floating inside the dirty control scope [freerun,
limit], a followup patch will use some refined dirty poll interval to
get the desired pause time.

   thresh-dirty (MB)    sqrt
		   1      16
		   2      22
		   4      32
		   8      45
		  16      64
		  32      90
		  64     128
		 128     181
		 256     256
		 512     362
		1024     512

The above table means, given 1MB (or 1GB) gap and the dd tasks polling
balance_dirty_pages() on every 16 (or 512) pages, the dirty limit won't
be exceeded as long as there are less than 16 (or 512) concurrent dd's.

So sqrt naturally leads to less overheads and more safe concurrent tasks
for large memory servers, which have large (thresh-freerun) gaps.

peter: keep the per-CPU ratelimit for safeguarding the 1k+ tasks case

CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Andrea Righi <andrea@betterlinux.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:57 +08:00
Wu Fengguang 7381131cbc writeback: stabilize bdi->dirty_ratelimit
There are some imperfections in balanced_dirty_ratelimit.

1) large fluctuations

The dirty_rate used for computing balanced_dirty_ratelimit is merely
averaged in the past 200ms (very small comparing to the 3s estimation
period for write_bw), which makes rather dispersed distribution of
balanced_dirty_ratelimit.

It's pretty hard to average out the singular points by increasing the
estimation period. Considering that the averaging technique will
introduce very undesirable time lags, I give it up totally. (btw, the 3s
write_bw averaging time lag is much more acceptable because its impact
is one-way and therefore won't lead to oscillations.)

The more practical way is filtering -- most singular
balanced_dirty_ratelimit points can be filtered out by remembering some
prev_balanced_rate and prev_prev_balanced_rate. However the more
reliable way is to guard balanced_dirty_ratelimit with task_ratelimit.

2) due to truncates and fs redirties, the (write_bw <=> dirty_rate)
match could become unbalanced, which may lead to large systematical
errors in balanced_dirty_ratelimit. The truncates, due to its possibly
bumpy nature, can hardly be compensated smoothly. So let's face it. When
some over-estimated balanced_dirty_ratelimit brings dirty_ratelimit
high, dirty pages will go higher than the setpoint. task_ratelimit will
in turn become lower than dirty_ratelimit.  So if we consider both
balanced_dirty_ratelimit and task_ratelimit and update dirty_ratelimit
only when they are on the same side of dirty_ratelimit, the systematical
errors in balanced_dirty_ratelimit won't be able to bring
dirty_ratelimit far away.

The balanced_dirty_ratelimit estimation may also be inaccurate near
@limit or @freerun, however is less an issue.

3) since we ultimately want to

- keep the fluctuations of task ratelimit as small as possible
- keep the dirty pages around the setpoint as long time as possible

the update policy used for (2) also serves the above goals nicely:
if for some reason the dirty pages are high (task_ratelimit < dirty_ratelimit),
and dirty_ratelimit is low (dirty_ratelimit < balanced_dirty_ratelimit),
there is no point to bring up dirty_ratelimit in a hurry only to hurt
both the above two goals.

So, we make use of task_ratelimit to limit the update of dirty_ratelimit
in two ways:

1) avoid changing dirty rate when it's against the position control target
   (the adjusted rate will slow down the progress of dirty pages going
   back to setpoint).

2) limit the step size. task_ratelimit is changing values step by step,
   leaving a consistent trace comparing to the randomly jumping
   balanced_dirty_ratelimit. task_ratelimit also has the nice smaller
   errors in stable state and typically larger errors when there are big
   errors in rate.  So it's a pretty good limiting factor for the step
   size of dirty_ratelimit.

Note that bdi->dirty_ratelimit is always tracking balanced_dirty_ratelimit.
task_ratelimit is merely used as a limiting factor.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:57 +08:00
Wu Fengguang be3ffa2764 writeback: dirty rate control
It's all about bdi->dirty_ratelimit, which aims to be (write_bw / N)
when there are N dd tasks.

On write() syscall, use bdi->dirty_ratelimit
============================================

    balance_dirty_pages(pages_dirtied)
    {
        task_ratelimit = bdi->dirty_ratelimit * bdi_position_ratio();
        pause = pages_dirtied / task_ratelimit;
        sleep(pause);
    }

On every 200ms, update bdi->dirty_ratelimit
===========================================

    bdi_update_dirty_ratelimit()
    {
        task_ratelimit = bdi->dirty_ratelimit * bdi_position_ratio();
        balanced_dirty_ratelimit = task_ratelimit * write_bw / dirty_rate;
        bdi->dirty_ratelimit = balanced_dirty_ratelimit
    }

Estimation of balanced bdi->dirty_ratelimit
===========================================

balanced task_ratelimit
-----------------------

balance_dirty_pages() needs to throttle tasks dirtying pages such that
the total amount of dirty pages stays below the specified dirty limit in
order to avoid memory deadlocks. Furthermore we desire fairness in that
tasks get throttled proportionally to the amount of pages they dirty.

IOW we want to throttle tasks such that we match the dirty rate to the
writeout bandwidth, this yields a stable amount of dirty pages:

        dirty_rate == write_bw                                          (1)

The fairness requirement gives us:

        task_ratelimit = balanced_dirty_ratelimit
                       == write_bw / N                                  (2)

where N is the number of dd tasks.  We don't know N beforehand, but
still can estimate balanced_dirty_ratelimit within 200ms.

Start by throttling each dd task at rate

        task_ratelimit = task_ratelimit_0                               (3)
                         (any non-zero initial value is OK)

After 200ms, we measured

        dirty_rate = # of pages dirtied by all dd's / 200ms
        write_bw   = # of pages written to the disk / 200ms

For the aggressive dd dirtiers, the equality holds

        dirty_rate == N * task_rate
                   == N * task_ratelimit_0                              (4)
Or
        task_ratelimit_0 == dirty_rate / N                              (5)

Now we conclude that the balanced task ratelimit can be estimated by

                                                      write_bw
        balanced_dirty_ratelimit = task_ratelimit_0 * ----------        (6)
                                                      dirty_rate

Because with (4) and (5) we can get the desired equality (1):

                                                       write_bw
        balanced_dirty_ratelimit == (dirty_rate / N) * ----------
                                                       dirty_rate
                                 == write_bw / N

Then using the balanced task ratelimit we can compute task pause times like:

        task_pause = task->nr_dirtied / task_ratelimit

task_ratelimit with position control
------------------------------------

However, while the above gives us means of matching the dirty rate to
the writeout bandwidth, it at best provides us with a stable dirty page
count (assuming a static system). In order to control the dirty page
count such that it is high enough to provide performance, but does not
exceed the specified limit we need another control.

The dirty position control works by extending (2) to

        task_ratelimit = balanced_dirty_ratelimit * pos_ratio           (7)

where pos_ratio is a negative feedback function that subjects to

1) f(setpoint) = 1.0
2) df/dx < 0

That is, if the dirty pages are ABOVE the setpoint, we throttle each
task a bit more HEAVY than balanced_dirty_ratelimit, so that the dirty
pages are created less fast than they are cleaned, thus DROP to the
setpoints (and the reverse).

Based on (7) and the assumption that both dirty_ratelimit and pos_ratio
remains CONSTANT for the past 200ms, we get

        task_ratelimit_0 = balanced_dirty_ratelimit * pos_ratio         (8)

Putting (8) into (6), we get the formula used in
bdi_update_dirty_ratelimit():

                                                write_bw
        balanced_dirty_ratelimit *= pos_ratio * ----------              (9)
                                                dirty_rate

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:56 +08:00
Wu Fengguang af6a311384 writeback: add bg_threshold parameter to __bdi_update_bandwidth()
No behavior change.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:56 +08:00
Wu Fengguang 6c14ae1e92 writeback: dirty position control
bdi_position_ratio() provides a scale factor to bdi->dirty_ratelimit, so
that the resulted task rate limit can drive the dirty pages back to the
global/bdi setpoints.

Old scheme is,
                                          |
                           free run area  |  throttle area
  ----------------------------------------+---------------------------->
                                    thresh^                  dirty pages

New scheme is,

  ^ task rate limit
  |
  |            *
  |             *
  |              *
  |[free run]      *      [smooth throttled]
  |                  *
  |                     *
  |                         *
  ..bdi->dirty_ratelimit..........*
  |                               .     *
  |                               .          *
  |                               .              *
  |                               .                 *
  |                               .                    *
  +-------------------------------.-----------------------*------------>
                          setpoint^                  limit^  dirty pages

The slope of the bdi control line should be

1) large enough to pull the dirty pages to setpoint reasonably fast

2) small enough to avoid big fluctuations in the resulted pos_ratio and
   hence task ratelimit

Since the fluctuation range of the bdi dirty pages is typically observed
to be within 1-second worth of data, the bdi control line's slope is
selected to be a linear function of bdi write bandwidth, so that it can
adapt to slow/fast storage devices well.

Assume the bdi control line

	pos_ratio = 1.0 + k * (dirty - bdi_setpoint)

where k is the negative slope.

If targeting for 12.5% fluctuation range in pos_ratio when dirty pages
are fluctuating in range

	[bdi_setpoint - write_bw/2, bdi_setpoint + write_bw/2],

we get slope

	k = - 1 / (8 * write_bw)

Let pos_ratio(x_intercept) = 0, we get the parameter used in code:

	x_intercept = bdi_setpoint + 8 * write_bw

The global/bdi slopes are nicely complementing each other when the
system has only one major bdi (indicated by bdi_thresh ~= thresh):

1) slope of global control line    => scaling to the control scope size
2) slope of main bdi control line  => scaling to the writeout bandwidth

so that

- in memory tight systems, (1) becomes strong enough to squeeze dirty
  pages inside the control scope

- in large memory systems where the "gravity" of (1) for pulling the
  dirty pages to setpoint is too weak, (2) can back (1) up and drive
  dirty pages to bdi_setpoint ~= setpoint reasonably fast.

Unfortunately in JBOD setups, the fluctuation range of bdi threshold
is related to memory size due to the interferences between disks.  In
this case, the bdi slope will be weighted sum of write_bw and bdi_thresh.

Given equations

        span = x_intercept - bdi_setpoint
        k = df/dx = - 1 / span

and the extremum values

        span = bdi_thresh
        dx = bdi_thresh

we get

        df = - dx / span = - 1.0

That means, when bdi_dirty deviates bdi_thresh up, pos_ratio and hence
task ratelimit will fluctuate by -100%.

peter: use 3rd order polynomial for the global control line

CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:56 +08:00
Wu Fengguang c8e28ce049 writeback: account per-bdi accumulated dirtied pages
Introduce the BDI_DIRTIED counter. It will be used for estimating the
bdi's dirty bandwidth.

CC: Jan Kara <jack@suse.cz>
CC: Michael Rubin <mrubin@google.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-03 21:08:56 +08:00
Alex Shi dcc3be6a54 slub: Discard slab page when node partial > minimum partial number
Discarding slab should be done when node partial > min_partial.  Otherwise,
node partial slab may eat up all memory.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-09-27 23:03:31 +03:00
Alex Shi 9f26490412 slub: correct comments error for per cpu partial
Correct comment errors, that mistake cpu partial objects number as pages
number, may make reader misunderstand.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-09-27 23:03:30 +03:00
Vasiliy Kulikov ab067e99d2 mm: restrict access to slab files under procfs and sysfs
Historically /proc/slabinfo and files under /sys/kernel/slab/* have
world read permissions and are accessible to the world.  slabinfo
contains rather private information related both to the kernel and
userspace tasks.  Depending on the situation, it might reveal either
private information per se or information useful to make another
targeted attack.  Some examples of what can be learned by
reading/watching for /proc/slabinfo entries:

1) dentry (and different *inode*) number might reveal other processes fs
activity.  The number of dentry "active objects" doesn't strictly show
file count opened/touched by a process, however, there is a good
correlation between them.  The patch "proc: force dcache drop on
unauthorized access" relies on the privacy of dentry count.

2) different inode entries might reveal the same information as (1), but
these are more fine granted counters.  If a filesystem is mounted in a
private mount point (or even a private namespace) and fs type differs from
other mounted fs types, fs activity in this mount point/namespace is
revealed.  If there is a single ecryptfs mount point, the whole fs
activity of a single user is revealed.  Number of files in ecryptfs
mount point is a private information per se.

3) fuse_* reveals number of files / fs activity of a user in a user
private mount point.  It is approx. the same severity as ecryptfs
infoleak in (2).

4) sysfs_dir_cache similar to (2) reveals devices' addition/removal,
which can be otherwise hidden by "chmod 0700 /sys/".  With 0444 slabinfo
the precise number of sysfs files is known to the world.

5) buffer_head might reveal some kernel activity.  With other
information leaks an attacker might identify what specific kernel
routines generate buffer_head activity.

6) *kmalloc* infoleaks are very situational.  Attacker should watch for
the specific kmalloc size entry and filter the noise related to the unrelated
kernel activity.  If an attacker has relatively silent victim system, he
might get rather precise counters.

Additional information sources might significantly increase the slabinfo
infoleak benefits.  E.g. if an attacker knows that the processes
activity on the system is very low (only core daemons like syslog and
cron), he may run setxid binaries / trigger local daemon activity /
trigger network services activity / await sporadic cron jobs activity
/ etc. and get rather precise counters for fs and network activity of
these privileged tasks, which is unknown otherwise.

Also hiding slabinfo and /sys/kernel/slab/* is a one step to complicate
exploitation of kernel heap overflows (and possibly, other bugs).  The
related discussion:

http://thread.gmane.org/gmane.linux.kernel/1108378

To keep compatibility with old permission model where non-root
monitoring daemon could watch for kernel memleaks though slabinfo one
should do:

    groupadd slabinfo
    usermod -a -G slabinfo $MONITOR_USER

And add the following commands to init scripts (to mountall.conf in
Ubuntu's upstart case):

    chmod g+r /proc/slabinfo /sys/kernel/slab/*/*
    chgrp slabinfo /proc/slabinfo /sys/kernel/slab/*/*

Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Reviewed-by: Kees Cook <kees@ubuntu.com>
Reviewed-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: David Rientjes <rientjes@google.com>
CC: Valdis.Kletnieks@vt.edu
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Alan Cox <alan@linux.intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-09-27 22:59:27 +03:00
Linus Torvalds fed678dc8a Merge branch 'for-linus' of git://git.kernel.dk/linux-block
* 'for-linus' of git://git.kernel.dk/linux-block:
  floppy: use del_timer_sync() in init cleanup
  blk-cgroup: be able to remove the record of unplugged device
  block: Don't check QUEUE_FLAG_SAME_COMP in __blk_complete_request
  mm: Add comment explaining task state setting in bdi_forker_thread()
  mm: Cleanup clearing of BDI_pending bit in bdi_forker_thread()
  block: simplify force plug flush code a little bit
  block: change force plug flush call order
  block: Fix queue_flag update when rq_affinity goes from 2 to 1
  block: separate priority boosting from REQ_META
  block: remove READ_META and WRITE_META
  xen-blkback: fixed indentation and comments
  xen-blkback: Don't disconnect backend until state switched to XenbusStateClosed.
2011-09-21 13:20:21 -07:00
Linus Torvalds b6a68a5ba4 Merge branch 'slab/urgent' of git://github.com/penberg/linux
* 'slab/urgent' of git://github.com/penberg/linux:
  slub: add slab with one free object to partial list tail
2011-09-19 08:02:41 -07:00
Pekka Enberg d20bbfab01 Merge branch 'slab/urgent' into slab/next 2011-09-19 17:46:07 +03:00
Jiri Kosina e060c38434 Merge branch 'master' into for-next
Fast-forward merge with Linus to be able to merge patches
based on more recent version of the tree.
2011-09-15 15:08:18 +02:00
Joe Perches 8c1fec1ba8 mm: Convert vmalloc/memset to vzalloc
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-09-15 13:56:56 +02:00
Shaohua Li cc39c6a9bb mm: account skipped entries to avoid looping in find_get_pages
The found entries by find_get_pages() could be all swap entries.  In
this case we skip the entries, but make sure the skipped entries are
accounted, so we don't keep looping.

Using nr_found > nr_skip to simplify code as suggested by Eric.

Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-14 18:17:56 -07:00
David Vrabel 461ae488ec mm: sync vmalloc address space page tables in alloc_vm_area()
Xen backend drivers (e.g., blkback and netback) would sometimes fail to
map grant pages into the vmalloc address space allocated with
alloc_vm_area().  The GNTTABOP_map_grant_ref would fail because Xen could
not find the page (in the L2 table) containing the PTEs it needed to
update.

(XEN) mm.c:3846:d0 Could not find L1 PTE for address fbb42000

netback and blkback were making the hypercall from a kernel thread where
task->active_mm != &init_mm and alloc_vm_area() was only updating the page
tables for init_mm.  The usual method of deferring the update to the page
tables of other processes (i.e., after taking a fault) doesn't work as a
fault cannot occur during the hypercall.

This would work on some systems depending on what else was using vmalloc.

Fix this by reverting ef691947d8 ("vmalloc: remove vmalloc_sync_all()
from alloc_vm_area()") and add a comment to explain why it's needed.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Keir Fraser <keir.xen@gmail.com>
Cc: <stable@kernel.org>		[3.0.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-14 18:09:38 -07:00
Johannes Weiner 185efc0f9a memcg: Revert "memcg: add memory.vmscan_stat"
Revert the post-3.0 commit 82f9d486e5 ("memcg: add
memory.vmscan_stat").

The implementation of per-memcg reclaim statistics violates how memcg
hierarchies usually behave: hierarchically.

The reclaim statistics are accounted to child memcgs and the parent
hitting the limit, but not to hierarchy levels in between.  Usually,
hierarchical statistics are perfectly recursive, with each level
representing the sum of itself and all its children.

Since this exports statistics to userspace, this may lead to confusion
and problems with changing things after the release, so revert it now,
we can try again later.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-14 18:09:38 -07:00
Johannes Weiner a4d3e9e763 mm: vmscan: fix force-scanning small targets without swap
Without swap, anonymous pages are not scanned.  As such, they should not
count when considering force-scanning a small target if there is no swap.

Otherwise, targets are not force-scanned even when their effective scan
number is zero and the other conditions--kswapd/memcg--apply.

This fixes 246e87a939 ("memcg: fix get_scan_count() for small
targets").

[akpm@linux-foundation.org: fix comment]
Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-14 18:09:37 -07:00
David Rientjes 0d6617c773 numa: fix NUMA compile error when sysfs and procfs are disabled
The vmstat_text array is only defined for CONFIG_SYSFS or CONFIG_PROC_FS,
yet it is referenced for per-node vmstat with CONFIG_NUMA:

	drivers/built-in.o: In function `node_read_vmstat':
	node.c:(.text+0x1106df): undefined reference to `vmstat_text'

Introduced in commit fa25c503df ("mm: per-node vmstat: show proper
vmstats").

Define the array for CONFIG_NUMA as well.

[akpm@linux-foundation.org: remove unneeded ifdefs]
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Cong Wang <amwang@redhat.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-14 18:09:37 -07:00
KAMEZAWA Hiroyuki 2bbff6c761 mm/mempolicy.c: make copy_from_user() provably correct
When compiling mm/mempolicy.c with struct user copy checks the following
warning is shown:

  In file included from arch/x86/include/asm/uaccess.h:572,
                   from include/linux/uaccess.h:5,
                   from include/linux/highmem.h:7,
                   from include/linux/pagemap.h:10,
                   from include/linux/mempolicy.h:70,
                   from mm/mempolicy.c:68:
  In function `copy_from_user',
      inlined from `compat_sys_get_mempolicy' at mm/mempolicy.c:1415:
  arch/x86/include/asm/uaccess_64.h:64: warning: call to `copy_from_user_overflow' declared with attribute warning: copy_from_user() buffer size is not provably correct
    LD      mm/built-in.o

Fix this by passing correct buffer size value.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-14 18:09:36 -07:00
Caspar Zhang 8aacc9f550 mm/mempolicy.c: fix pgoff in mbind vma merge
commit 9d8cebd4bc ("mm: fix mbind vma merge problem") didn't really
fix the mbind vma merge problem due to wrong pgoff value passing to
vma_merge(), which made vma_merge() always return NULL.

Before the patch applied, we are getting a result like:

  addr = 0x7fa58f00c000
  [snip]
  7fa58f00c000-7fa58f00d000 rw-p 00000000 00:00 0
  7fa58f00d000-7fa58f00e000 rw-p 00000000 00:00 0
  7fa58f00e000-7fa58f00f000 rw-p 00000000 00:00 0

here 7fa58f00c000->7fa58f00f000 we get 3 VMAs which are expected to be
merged described as described in commit 9d8cebd.

Re-testing the patched kernel with the reproducer provided in commit
9d8cebd, we get the correct result:

  addr = 0x7ffa5aaa2000
  [snip]
  7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
  7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0                          [stack]

Signed-off-by: Caspar Zhang <caspar@casparzhang.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-14 18:09:36 -07:00
Alex,Shi 12d79634f8 slub: Code optimization in get_partial_node()
I find a way to reduce a variable in get_partial_node(). That is also helpful
for code understanding.

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-09-13 20:41:25 +03:00
Jan Kara 09f40f98bf mm: Add comment explaining task state setting in bdi_forker_thread()
CC: Wu Fengguang <fengguang.wu@intel.com>
CC: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-09-02 17:17:02 -06:00
Jan Kara 5a042aa4b8 mm: Cleanup clearing of BDI_pending bit in bdi_forker_thread()
bdi_forker_thread() clears BDI_pending bit at the end of the main loop.
However clearing of this bit must not be done in some cases which is
handled by calling 'continue' from switch statement. That's kind of
unusual construct and without a good reason so change the function into
more intuitive code flow.

CC: Wu Fengguang <fengguang.wu@intel.com>
CC: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-09-02 17:17:02 -06:00
Shaohua Li 136333d104 slub: explicitly document position of inserting slab to partial list
Adding slab to partial list head/tail is sensitive to performance.
So explicitly uses DEACTIVATE_TO_TAIL/DEACTIVATE_TO_HEAD to document
it to avoid we get it wrong.

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Shaohua Li <shli@kernel.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-27 11:59:00 +03:00
Shaohua Li 130655ef09 slub: add slab with one free object to partial list tail
The slab has just one free object, adding it to partial list head doesn't make
sense. And it can cause lock contentation. For example,
1. CPU takes the slab from partial list
2. fetch an object
3. switch to another slab
4. free an object, then the slab is added to partial list again
In this way n->list_lock will be heavily contended.
In fact, Alex had a hackbench regression. 3.1-rc1 performance drops about 70%
against 3.0. This patch fixes it.

Acked-by: Christoph Lameter <cl@linux.com>
Reported-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Shaohua Li <shli@kernel.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-27 11:58:59 +03:00
Johannes Weiner 23751be009 memcg: fix hierarchical oom locking
Commit 79dfdaccd1 ("memcg: make oom_lock 0 and 1 based rather than
counter") tried to oom lock the hierarchy and roll back upon
encountering an already locked memcg.

The code is confused when it comes to detecting a locked memcg, though,
so it would fail and rollback after locking one memcg and encountering
an unlocked second one.

The result is that oom-locking hierarchies fails unconditionally and
that every oom killer invocation simply goes to sleep on the oom
waitqueue forever.  The tasks practically hang forever without anyone
intervening, possibly holding locks that trip up unrelated tasks, too.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-25 16:25:34 -07:00
Shaohua Li 439423f689 vmscan: clear ZONE_CONGESTED for zone with good watermark
ZONE_CONGESTED is only cleared in kswapd, but pages can be freed in any
task.  It's possible ZONE_CONGESTED isn't cleared in some cases:

 1. the zone is already balanced just entering balance_pgdat() for
    order-0 because concurrent tasks free memory.  In this case, later
    check will skip the zone as it's balanced so the flag isn't cleared.

 2. high order balance fallbacks to order-0.  quote from Mel: At the
    end of balance_pgdat(), kswapd uses the following logic;

	If reclaiming at high order {
		for each zone {
			if all_unreclaimable
				skip
			if watermark is not met
				order = 0
				loop again

			/* watermark is met */
			clear congested
		}
	}

    i.e. it clears ZONE_CONGESTED if it the zone is balanced.  if not,
    it restarts balancing at order-0.  However, if the higher zones are
    balanced for order-0, kswapd will miss clearing ZONE_CONGESTED as
    that only happens after a zone is shrunk.  This can mean that
    wait_iff_congested() stalls unnecessarily.

This patch makes kswapd clear ZONE_CONGESTED during its initial
highmem->dma scan for zones that are already balanced.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-25 16:25:34 -07:00
Shaohua Li f51bdd2e97 mm: fix a vmscan warning
I get the below warning:

  BUG: using smp_processor_id() in preemptible [00000000] code: bash/746
  caller is native_sched_clock+0x37/0x6e
  Pid: 746, comm: bash Tainted: G        W   3.0.0+ #254
  Call Trace:
   [<ffffffff813435c6>] debug_smp_processor_id+0xc2/0xdc
   [<ffffffff8104158d>] native_sched_clock+0x37/0x6e
   [<ffffffff81116219>] try_to_free_mem_cgroup_pages+0x7d/0x270
   [<ffffffff8114f1f8>] mem_cgroup_force_empty+0x24b/0x27a
   [<ffffffff8114ff21>] ? sys_close+0x38/0x138
   [<ffffffff8114ff21>] ? sys_close+0x38/0x138
   [<ffffffff8114f257>] mem_cgroup_force_empty_write+0x17/0x19
   [<ffffffff810c72fb>] cgroup_file_write+0xa8/0xba
   [<ffffffff811522d2>] vfs_write+0xb3/0x138
   [<ffffffff8115241a>] sys_write+0x4a/0x71
   [<ffffffff8114ffd9>] ? sys_close+0xf0/0x138
   [<ffffffff8176deab>] system_call_fastpath+0x16/0x1b

sched_clock() can't be used with preempt enabled.  And we don't need
fast approach to get clock here, so let's use ktime API.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-25 16:25:34 -07:00
Johannes Weiner 5af12d0efd memcg: pin execution to current cpu while draining stock
Commit d1a05b6973 ("memcg do not try to drain per-cpu caches without
pages") added a drain_local_stock() call to a preemptible section.

The draining task looks up the cpu-local stock twice to set the
draining-flag, then to drain the stock and clear the flag again.  If the
task is migrated to a different CPU in between, noone will clear the
flag on the first stock and it will be forever undrainable.  Its charge
can not be recovered and the cgroup can not be deleted anymore.

Properly pin the task to the executing CPU while draining stocks.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-25 16:25:33 -07:00
Linus Torvalds e33f2d238e Merge branch 'urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback
* 'urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback:
  squeeze max-pause area and drop pass-good area
2011-08-25 10:40:12 -07:00
Justin P. Mattock 81d66c70b5 mm/vmscan.c: fix a typo in a comment "relaimed" to "reclaimed"
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-08-24 16:45:10 +02:00
Christoph Lameter 49e2258586 slub: per cpu cache for partial pages
Allow filling out the rest of the kmem_cache_cpu cacheline with pointers to
partial pages. The partial page list is used in slab_free() to avoid
per node lock taking.

In __slab_alloc() we can then take multiple partial pages off the per
node partial list in one go reducing node lock pressure.

We can also use the per cpu partial list in slab_alloc() to avoid scanning
partial lists for pages with free objects.

The main effect of a per cpu partial list is that the per node list_lock
is taken for batches of partial pages instead of individual ones.

Potential future enhancements:

1. The pickup from the partial list could be perhaps be done without disabling
   interrupts with some work. The free path already puts the page into the
   per cpu partial list without disabling interrupts.

2. __slab_free() may have some code paths that could use optimization.

Performance:

				Before		After
./hackbench 100 process 200000
				Time: 1953.047	1564.614
./hackbench 100 process 20000
				Time: 207.176   156.940
./hackbench 100 process 20000
				Time: 204.468	156.940
./hackbench 100 process 20000
				Time: 204.879	158.772
./hackbench 10 process 20000
				Time: 20.153	15.853
./hackbench 10 process 20000
				Time: 20.153	15.986
./hackbench 10 process 20000
				Time: 19.363	16.111
./hackbench 1 process 20000
				Time: 2.518	2.307
./hackbench 1 process 20000
				Time: 2.258	2.339
./hackbench 1 process 20000
				Time: 2.864	2.163

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19 19:34:27 +03:00
Christoph Lameter 497b66f2ec slub: return object pointer from get_partial() / new_slab().
There is no need anymore to return the pointer to a slab page from get_partial()
since the page reference can be stored in the kmem_cache_cpu structures "page" field.

Return an object pointer instead.

That in turn allows a simplification of the spaghetti code in __slab_alloc().

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19 19:34:27 +03:00
Christoph Lameter acd19fd1a7 slub: pass kmem_cache_cpu pointer to get_partial()
Pass the kmem_cache_cpu pointer to get_partial(). That way
we can avoid the this_cpu_write() statements.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19 19:34:26 +03:00
Christoph Lameter e6e82ea112 slub: Prepare inuse field in new_slab()
inuse will always be set to page->objects. There is no point in
initializing the field to zero in new_slab() and then overwriting
the value in __slab_alloc().

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19 19:34:26 +03:00
Christoph Lameter 7db0d70540 slub: Remove useless statements in __slab_alloc
Two statements in __slab_alloc() do not have any effect.

1. c->page is already set to NULL by deactivate_slab() called right before.

2. gfpflags are masked in new_slab() before being passed to the page
   allocator. There is no need to mask gfpflags in __slab_alloc in particular
   since most frequent processing in __slab_alloc does not require the use of a
   gfpmask.

Cc: torvalds@linux-foundation.org
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19 19:34:25 +03:00
Christoph Lameter 69cb8e6b7c slub: free slabs without holding locks
There are two situations in which slub holds a lock while releasing
pages:

	A. During kmem_cache_shrink()
	B. During kmem_cache_close()

For A build a list while holding the lock and then release the pages
later. In case of B we are the last remaining user of the slab so
there is no need to take the listlock.

After this patch all calls to the page allocator to free pages are
done without holding any spinlocks. kmem_cache_destroy() will still
hold the slub_lock semaphore.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19 19:34:25 +03:00
Wu Fengguang bb0822954a squeeze max-pause area and drop pass-good area
Revert the pass-good area introduced in ffd1f609ab ("writeback:
introduce max-pause and pass-good dirty limits") and make the max-pause
area smaller and safe.

This fixes ~30% performance regression in the ext3 data=writeback
fio_mmap_randwrite_64k/fio_mmap_randrw_64k test cases, where there are
12 JBOD disks, on each disk runs 8 concurrent tasks doing reads+writes.

Using deadline scheduler also has a regression, but not that big as CFQ,
so this suggests we have some write starvation.

The test logs show that

- the disks are sometimes under utilized

- global dirty pages sometimes rush high to the pass-good area for
  several hundred seconds, while in the mean time some bdi dirty pages
  drop to very low value (bdi_dirty << bdi_thresh).  Then suddenly the
  global dirty pages dropped under global dirty threshold and bdi_dirty
  rush very high (for example, 2 times higher than bdi_thresh). During
  which time balance_dirty_pages() is not called at all.

So the problems are

1) The random writes progress so slow that they break the assumption of
   the max-pause logic that "8 pages per 200ms is typically more than
   enough to curb heavy dirtiers".

2) The max-pause logic ignored task_bdi_thresh and thus opens the possibility
   for some bdi's to over dirty pages, leading to (bdi_dirty >> bdi_thresh)
   and then (bdi_thresh >> bdi_dirty) for others.

3) The higher max-pause/pass-good thresholds somehow leads to the bad
   swing of dirty pages.

The fix is to allow the task to slightly dirty over task_bdi_thresh, but
no way to exceed bdi_dirty and/or global dirty_thresh.

Tests show that it fixed the JBOD regression completely (both behavior
and performance), while still being able to cut down large pause times
in balance_dirty_pages() for single-disk cases.

Reported-by: Li Shaohua <shaohua.li@intel.com>
Tested-by: Li Shaohua <shaohua.li@intel.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-08-19 22:42:07 +08:00
Ian Campbell f991879473 mm: make HASHED_PAGE_VIRTUAL page_address' struct page argument const.
Followup to 33dd4e0ec9 "mm: make some struct page's const" which missed the
HASHED_PAGE_VIRTUAL case.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-17 13:00:20 -07:00
Clemens Ladisch f982f91516 mm: fix wrong vmap address calculations with odd NR_CPUS values
Commit db64fe0225 ("mm: rewrite vmap layer") introduced code that does
address calculations under the assumption that VMAP_BLOCK_SIZE is a
power of two.  However, this might not be true if CONFIG_NR_CPUS is not
set to a power of two.

Wrong vmap_block index/offset values could lead to memory corruption.
However, this has never been observed in practice (or never been
diagnosed correctly); what caught this was the BUG_ON in vb_alloc() that
checks for inconsistent vmap_block indices.

To fix this, ensure that VMAP_BLOCK_SIZE always is a power of two.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=31572
Reported-by: Pavel Kysilka <goldenfish@linuxsoft.cz>
Reported-by: Matias A. Fonzo <selk@dragora.org>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: 2.6.28+ <stable@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-14 12:32:52 -07:00
Michal Hocko 9f50fad65b Revert "memcg: get rid of percpu_charge_mutex lock"
This reverts commit 8521fc50d4.

The patch incorrectly assumes that using atomic FLUSHING_CACHED_CHARGE
bit operations is sufficient but that is not true.  Johannes Weiner has
reported a crash during parallel memory cgroup removal:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
  IP: [<ffffffff81083b70>] css_is_ancestor+0x20/0x70
  Oops: 0000 [#1] PREEMPT SMP
  Pid: 19677, comm: rmdir Tainted: G        W   3.0.0-mm1-00188-gf38d32b #35 ECS MCP61M-M3/MCP61M-M3
  RIP: 0010:[<ffffffff81083b70>]  css_is_ancestor+0x20/0x70
  RSP: 0018:ffff880077b09c88  EFLAGS: 00010202
  Process rmdir (pid: 19677, threadinfo ffff880077b08000, task ffff8800781bb310)
  Call Trace:
   [<ffffffff810feba3>] mem_cgroup_same_or_subtree+0x33/0x40
   [<ffffffff810feccf>] drain_all_stock+0x11f/0x170
   [<ffffffff81103211>] mem_cgroup_force_empty+0x231/0x6d0
   [<ffffffff811036c4>] mem_cgroup_pre_destroy+0x14/0x20
   [<ffffffff81080559>] cgroup_rmdir+0xb9/0x500
   [<ffffffff81114d26>] vfs_rmdir+0x86/0xe0
   [<ffffffff81114e7b>] do_rmdir+0xfb/0x110
   [<ffffffff81114ea6>] sys_rmdir+0x16/0x20
   [<ffffffff8154d76b>] system_call_fastpath+0x16/0x1b

We are crashing because we try to dereference cached memcg when we are
checking whether we should wait for draining on the cache.  The cache is
already cleaned up, though.

There is also a theoretical chance that the cached memcg gets freed
between we test for the FLUSHING_CACHED_CHARGE and dereference it in
mem_cgroup_same_or_subtree:

        CPU0                    CPU1                         CPU2
  mem=stock->cached
  stock->cached=NULL
                              clear_bit
                                                        test_and_set_bit
  test_bit()                    ...
  <preempted>             mem_cgroup_destroy
  use after free

The percpu_charge_mutex protected from this race because sync draining
is exclusive.

It is safer to revert now and come up with a more parallel
implementation later.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-09 17:04:43 -07:00
Christoph Lameter 81107188f1 slub: Fix partial count comparison confusion
deactivate_slab() has the comparison if more than the minimum number of
partial pages are in the partial list wrong. An effect of this may be that
empty pages are not freed from deactivate_slab(). The result could be an
OOM due to growth of the partial slabs per node. Frees mostly occur from
__slab_free which is okay so this would only affect use cases where a lot
of switching around of per cpu slabs occur.

Switching per cpu slabs occurs with high frequency if debugging options are
enabled.

Reported-and-tested-by: Xiaotian Feng <xtfeng@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-09 21:12:31 +03:00
Akinobu Mita ef62fb32b7 slub: fix check_bytes() for slub debugging
The check_bytes() function is used by slub debugging.  It returns a pointer
to the first unmatching byte for a character in the given memory area.

If the character for matching byte is greater than 0x80, check_bytes()
doesn't work.  Becuase 64-bit pattern is generated as below.

	value64 = value | value << 8 | value << 16 | value << 24;
	value64 = value64 | value64 << 32;

The integer promotions are performed and sign-extended as the type of value
is u8.  The upper 32 bits of value64 is 0xffffffff in the first line, and
the second line has no effect.

This fixes the 64-bit pattern generation.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Matt Mackall <mpm@selenic.com>
Reviewed-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-09 16:37:48 +03:00
Christoph Lameter 6fbabb20fa slub: Fix full list corruption if debugging is on
When a slab is freed by __slab_free() and the slab can only contain a
single object ever then it was full (and therefore not on the partial
lists but on the full list in the debug case) before we reached
slab_empty.

This caused the following full list corruption when SLUB debugging was enabled:

  [ 5913.233035] ------------[ cut here ]------------
  [ 5913.233097] WARNING: at lib/list_debug.c:53 __list_del_entry+0x8d/0x98()
  [ 5913.233101] Hardware name: Adamo 13
  [ 5913.233105] list_del corruption. prev->next should be ffffea000434fd20, but was ffffea0004199520
  [ 5913.233108] Modules linked in: nfs fscache fuse ebtable_nat ebtables ppdev parport_pc lp parport ipt_MASQUERADE iptable_nat nf_nat nfsd lockd nfs_acl auth_rpcgss xt_CHECKSUM sunrpc iptable_mangle bridge stp llc cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables rfcomm bnep arc4 iwlagn snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_intel btusb mac80211 snd_hda_codec bluetooth snd_hwdep snd_seq snd_seq_device snd_pcm usb_debug dell_wmi sparse_keymap cdc_ether usbnet cdc_acm uvcvideo cdc_wdm mii cfg80211 snd_timer dell_laptop videodev dcdbas snd microcode v4l2_compat_ioctl32 soundcore joydev tg3 pcspkr snd_page_alloc iTCO_wdt i2c_i801 rfkill iTCO_vendor_support wmi virtio_net kvm_intel kvm ipv6 xts gf128mul dm_crypt i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan]
  [ 5913.233213] Pid: 0, comm: swapper Not tainted 3.0.0+ #127
  [ 5913.233213] Call Trace:
  [ 5913.233213]  <IRQ>  [<ffffffff8105df18>] warn_slowpath_common+0x83/0x9b
  [ 5913.233213]  [<ffffffff8105dfd3>] warn_slowpath_fmt+0x46/0x48
  [ 5913.233213]  [<ffffffff8127e7c1>] __list_del_entry+0x8d/0x98
  [ 5913.233213]  [<ffffffff8127e7da>] list_del+0xe/0x2d
  [ 5913.233213]  [<ffffffff814e0430>] __slab_free+0x1db/0x235
  [ 5913.233213]  [<ffffffff811706ab>] ? bvec_free_bs+0x35/0x37
  [ 5913.233213]  [<ffffffff811706ab>] ? bvec_free_bs+0x35/0x37
  [ 5913.233213]  [<ffffffff811706ab>] ? bvec_free_bs+0x35/0x37
  [ 5913.233213]  [<ffffffff81133085>] kmem_cache_free+0x88/0x102
  [ 5913.233213]  [<ffffffff811706ab>] bvec_free_bs+0x35/0x37
  [ 5913.233213]  [<ffffffff811706e1>] bio_free+0x34/0x64
  [ 5913.233213]  [<ffffffff813dc390>] dm_bio_destructor+0x12/0x14
  [ 5913.233213]  [<ffffffff8116fef6>] bio_put+0x2b/0x2d
  [ 5913.233213]  [<ffffffff813dccab>] clone_endio+0x9e/0xb4
  [ 5913.233213]  [<ffffffff8116f7dd>] bio_endio+0x2d/0x2f
  [ 5913.233213]  [<ffffffffa00148da>] crypt_dec_pending+0x5c/0x8b [dm_crypt]
  [ 5913.233213]  [<ffffffffa00150a9>] crypt_endio+0x78/0x81 [dm_crypt]

[ Full discussion here: https://lkml.org/lkml/2011/8/4/375 ]

Make sure that we remove such a slab also from the full lists.

Reported-and-tested-by: Dave Jones <davej@redhat.com>
Reported-and-tested-by: Xiaotian Feng <xtfeng@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-09 16:36:02 +03:00
James Morris 5a2f3a02ae Merge branch 'next-evm' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/ima-2.6 into next
Conflicts:
	fs/attr.c

Resolve conflict manually.

Signed-off-by: James Morris <jmorris@namei.org>
2011-08-09 10:31:03 +10:00
Linus Torvalds f03683b8fb Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  slab, lockdep: Annotate the locks before using them
  lockdep: Clear whole lockdep_map on initialization
  slab, lockdep: Annotate slab -> rcu -> debug_object -> slab
  lockdep: Fix up warning
  lockdep: Fix trace_hardirqs_on_caller()
  futex: Fix regression with read only mappings
2011-08-04 16:44:04 -10:00
Peter Zijlstra 30765b92ad slab, lockdep: Annotate the locks before using them
Fernando found we hit the regular OFF_SLAB 'recursion' before we
annotate the locks, cure this.

The relevant portion of the stack-trace:

> [    0.000000]  [<c085e24f>] rt_spin_lock+0x50/0x56
> [    0.000000]  [<c04fb406>] __cache_free+0x43/0xc3
> [    0.000000]  [<c04fb23f>] kmem_cache_free+0x6c/0xdc
> [    0.000000]  [<c04fb2fe>] slab_destroy+0x4f/0x53
> [    0.000000]  [<c04fb396>] free_block+0x94/0xc1
> [    0.000000]  [<c04fc551>] do_tune_cpucache+0x10b/0x2bb
> [    0.000000]  [<c04fc8dc>] enable_cpucache+0x7b/0xa7
> [    0.000000]  [<c0bd9d3c>] kmem_cache_init_late+0x1f/0x61
> [    0.000000]  [<c0bba687>] start_kernel+0x24c/0x363
> [    0.000000]  [<c0bba0ba>] i386_start_kernel+0xa9/0xaf

Reported-by: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>
Acked-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1311888176.2617.379.camel@laptop
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-04 10:18:00 +02:00
Peter Zijlstra 83835b3d9a slab, lockdep: Annotate slab -> rcu -> debug_object -> slab
Lockdep thinks there's lock recursion through:

	kmem_cache_free()
	  cache_flusharray()
	    spin_lock(&l3->list_lock)  <----------------.
	    free_block()                                |
	      slab_destroy()                            |
		call_rcu()                              |
		  debug_object_activate()               |
		    debug_object_init()                 |
		      __debug_object_init()             |
			kmem_cache_alloc()              |
			  cache_alloc_refill()          |
			    spin_lock(&l3->list_lock) --'

Now debug objects doesn't use SLAB_DESTROY_BY_RCU and hence there is no
actual possibility of recursing. Luckily debug objects marks it slab
with SLAB_DEBUG_OBJECTS so we can identify the thing.

Mark all SLAB_DEBUG_OBJECTS (all one!) slab caches with a special
lockdep key so that lockdep sees its a different cachep.

Also add a WARN on trying to create a SLAB_DESTROY_BY_RCU |
SLAB_DEBUG_OBJECTS cache, to avoid possible future trouble.

Reported-and-tested-by: Sebastian Siewior <sebastian@breakpoint.cc>
[ fixes to the initial patch ]
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1311341165.27400.58.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-04 10:17:54 +02:00
Linus Torvalds c0c770e610 Merge branch 'apei-release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
* 'apei-release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6:
  ACPI, APEI, EINJ Param support is disabled by default
  APEI GHES: 32-bit buildfix
  ACPI: APEI build fix
  ACPI, APEI, GHES: Add hardware memory error recovery support
  HWPoison: add memory_failure_queue()
  ACPI, APEI, GHES, Error records content based throttle
  ACPI, APEI, GHES, printk support for recoverable error via NMI
  lib, Make gen_pool memory allocator lockless
  lib, Add lock-less NULL terminated single list
  Add Kconfig option ARCH_HAVE_NMI_SAFE_CMPXCHG
  ACPI, APEI, Add WHEA _OSC support
  ACPI, APEI, Add APEI bit support in generic _OSC call
  ACPI, APEI, GHES, Support disable GHES at boot time
  ACPI, APEI, GHES, Prevent GHES to be built as module
  ACPI, APEI, Use apei_exec_run_optional in APEI EINJ and ERST
  ACPI, APEI, Add apei_exec_run_optional
  ACPI, APEI, GHES, Do not ratelimit fatal error printk before panic
  ACPI, APEI, ERST, Fix erst-dbg long record reading issue
  ACPI, APEI, ERST, Prevent erst_dbg from loading if ERST is disabled
2011-08-03 21:53:27 -10:00
Hugh Dickins 8079b1c859 mm: clarify the radix_tree exceptional cases
Make the radix_tree exceptional cases, mostly in filemap.c, clearer.

It's hard to devise a suitable snappy name that illuminates the use by
shmem/tmpfs for swap, while keeping filemap/pagecache/radix_tree
generality.  And akpm points out that /* radix_tree_deref_retry(page) */
comments look like calls that have been commented out for unknown
reason.

Skirt the naming difficulty by rearranging these blocks to handle the
transient radix_tree_deref_retry(page) case first; then just explain the
remaining shmem/tmpfs swap case in a comment.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:24 -10:00
Hugh Dickins e504f3fdd6 tmpfs radix_tree: locate_item to speed up swapoff
We have already acknowledged that swapoff of a tmpfs file is slower than
it was before conversion to the generic radix_tree: a little slower
there will be acceptable, if the hotter paths are faster.

But it was a shock to find swapoff of a 500MB file 20 times slower on my
laptop, taking 10 minutes; and at that rate it significantly slows down
my testing.

Now, most of that turned out to be overhead from PROVE_LOCKING and
PROVE_RCU: without those it was only 4 times slower than before; and
more realistic tests on other machines don't fare as badly.

I've tried a number of things to improve it, including tagging the swap
entries, then doing lookup by tag: I'd expected that to halve the time,
but in practice it's erratic, and often counter-productive.

The only change I've so far found to make a consistent improvement, is
to short-circuit the way we go back and forth, gang lookup packing
entries into the array supplied, then shmem scanning that array for the
target entry.  Scanning in place doubles the speed, so it's now only
twice as slow as before (or three times slower when the PROVEs are on).

So, add radix_tree_locate_item() as an expedient, once-off,
single-caller hack to do the lookup directly in place.  #ifdef it on
CONFIG_SHMEM and CONFIG_SWAP, as much to document its limited
applicability as save space in other configurations.  And, sadly,
#include sched.h for cond_resched().

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:24 -10:00
Hugh Dickins 31475dd611 mm: a few small updates for radix-swap
Remove PageSwapBacked (!page_is_file_cache) cases from
add_to_page_cache_locked() and add_to_page_cache_lru(): those pages now
go through shmem_add_to_page_cache().

Remove a comment on maximum tmpfs size from fsstack_copy_inode_size(),
and add a comment on swap entries to invalidate_mapping_pages().

And mincore_page() uses find_get_page() on what might be shmem or a
tmpfs file: allow for a radix_tree_exceptional_entry(), and proceed to
find_get_page() on swapper_space if so (oh, swapper_space needs #ifdef).

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:24 -10:00
Hugh Dickins 69f07ec938 tmpfs: use kmemdup for short symlinks
But we've not yet removed the old swp_entry_t i_direct[16] from
shmem_inode_info.  That's because it was still being shared with the
inline symlink.  Remove it now (saving 64 or 128 bytes from shmem inode
size), and use kmemdup() for short symlinks, say, those up to 128 bytes.

I wonder why mpol_free_shared_policy() is done in shmem_destroy_inode()
rather than shmem_evict_inode(), where we usually do such freeing? I
guess it doesn't matter, and I'm not into NUMA mpol testing right now.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:24 -10:00
Hugh Dickins 6922c0c7ab tmpfs: convert shmem_writepage and enable swap
Convert shmem_writepage() to use shmem_delete_from_page_cache() to use
shmem_radix_tree_replace() to substitute swap entry for page pointer
atomically in the radix tree.

As with shmem_add_to_page_cache(), it's not entirely satisfactory to be
copying such code from delete_from_swap_cache, but again judged easier
to sell than making its other callers go through the extras.

Remove the toy implementation's shmem_put_swap() and shmem_get_swap(),
now unreferenced, and the hack to disable swap: it's now good to go.

The way things have worked out, info->lock no longer helps to guard the
shmem_swaplist: we increment swapped under shmem_swaplist_mutex only.
That global mutex exclusion between shmem_writepage() and shmem_unuse()
is not pretty, and we ought to find another way; but it's been forced on
us by recent race discoveries, not a consequence of this patchset.

And what has become of the WARN_ON_ONCE(1) free_swap_and_cache() if a
swap entry was found already present? That's no longer possible, the
(unknown) one inserting this page into filecache would hit the swap
entry occupying that slot.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:24 -10:00
Hugh Dickins aa3b189551 tmpfs: convert mem_cgroup shmem to radix-swap
Remove mem_cgroup_shmem_charge_fallback(): it was only required when we
had to move swappage to filecache with GFP_NOWAIT.

Remove the GFP_NOWAIT special case from mem_cgroup_cache_charge(), by
moving its call out from shmem_add_to_page_cache() to two of thats three
callers.  But leave it doing mem_cgroup_uncharge_cache_page() on error:
although asymmetrical, it's easier for all 3 callers to handle.

These two changes would also be appropriate if anyone were to start
using shmem_read_mapping_page_gfp() with GFP_NOWAIT.

Remove mem_cgroup_get_shmem_target(): mc_handle_file_pte() can test
radix_tree_exceptional_entry() to get what it needs for itself.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:24 -10:00
Hugh Dickins 54af604218 tmpfs: convert shmem_getpage_gfp to radix-swap
Convert shmem_getpage_gfp(), the engine-room of shmem, to expect page or
swap entry returned from radix tree by find_lock_page().

Whereas the repetitive old method proceeded mainly under info->lock,
dropping and repeating whenever one of the conditions needed was not
met, now we can proceed without it, leaving shmem_add_to_page_cache() to
check for a race.

This way there is no need to preallocate a page, no need for an early
radix_tree_preload(), no need for mem_cgroup_shmem_charge_fallback().

Move the error unwinding down to the bottom instead of repeating it
throughout.  ENOSPC handling is a little different from before: there is
no longer any race between find_lock_page() and finding swap, but we can
arrive at ENOSPC before calling shmem_recalc_inode(), which might
occasionally discover freed space.

Be stricter to check i_size before returning.  info->lock is used for
little but alloced, swapped, i_blocks updates.  Move i_blocks updates
out from under the max_blocks check, so even an unlimited size=0 mount
can show accurate du.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:23 -10:00
Hugh Dickins 46f65ec15c tmpfs: convert shmem_unuse_inode to radix-swap
Convert shmem_unuse_inode() to use a lockless gang lookup of the radix
tree, searching for matching swap.

This is somewhat slower than the old method: because of repeated radix
tree descents, because of copying entries up, but probably most because
the old method noted and skipped once a vector page was cleared of swap.
Perhaps we can devise a use of radix tree tagging to achieve that later.

shmem_add_to_page_cache() uses shmem_radix_tree_replace() to compensate
for the lockless lookup by checking that the expected entry is in place,
under lock.  It is not very satisfactory to be copying this much from
add_to_page_cache_locked(), but I think easier to sell than insisting
that every caller of add_to_page_cache*() go through the extras.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:23 -10:00
Hugh Dickins 7a5d0fbb29 tmpfs: convert shmem_truncate_range to radix-swap
Disable the toy swapping implementation in shmem_writepage() - it's hard
to support two schemes at once - and convert shmem_truncate_range() to a
lockless gang lookup of swap entries along with pages, freeing both.

Since the second loop tightens its noose until all entries of either
kind have been squeezed out (and we shall make sure that there's not an
instant when neither is visible), there is no longer a need for yet
another pass below.

shmem_radix_tree_replace() compensates for the lockless lookup by
checking that the expected entry is in place, under lock, before
replacing it.  Here it just deletes, but will be used in later patches
to substitute swap entry for page or page for swap entry.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:23 -10:00
Hugh Dickins bda97eab0c tmpfs: copy truncate_inode_pages_range
Bring truncate.c's code for truncate_inode_pages_range() inline into
shmem_truncate_range(), replacing its first call (there's a followup
call below, but leave that one, it will disappear next).

Don't play with it yet, apart from leaving out the cleancache flush, and
(importantly) the nrpages == 0 skip, and moving shmem_setattr()'s
partial page preparation into its partial page handling.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:23 -10:00
Hugh Dickins 41ffe5d5ce tmpfs: miscellaneous trivial cleanups
While it's at its least, make a number of boring nitpicky cleanups to
shmem.c, mostly for consistency of variable naming.  Things like "swap"
instead of "entry", "pgoff_t index" instead of "unsigned long idx".

And since everything else here is prefixed "shmem_", better change
init_tmpfs() to shmem_init().

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:23 -10:00
Hugh Dickins 285b2c4fdd tmpfs: demolish old swap vector support
The maximum size of a shmem/tmpfs file has been limited by the maximum
size of its triple-indirect swap vector.  With 4kB page size, maximum
filesize was just over 2TB on a 32-bit kernel, but sadly one eighth of
that on a 64-bit kernel.  (With 8kB page size, maximum filesize was just
over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
MAX_LFS_FILESIZE being then more restrictive than swap vector layout.)

It's a shame that tmpfs should be more restrictive than ramfs, and this
limitation has now been noticed.  Add another level to the swap vector?
No, it became obscure and hard to maintain, once I complicated it to
make use of highmem pages nine years ago: better choose another way.

Surely, if 2.4 had had the radix tree pagecache introduced in 2.5, then
tmpfs would never have invented its own peculiar radix tree: we would
have fitted swap entries into the common radix tree instead, in much the
same way as we fit swap entries into page tables.

And why should each file have a separate radix tree for its pages and
for its swap entries? The swap entries are required precisely where and
when the pages are not.  We want to put them together in a single radix
tree: which can then avoid much of the locking which was needed to
prevent them from being exchanged underneath us.

This also avoids the waste of memory devoted to swap vectors, first in
the shmem_inode itself, then at least two more pages once a file grew
beyond 16 data pages (pages accounted by df and du, but not by memcg).
Allocated upfront, to avoid allocation when under swapping pressure, but
pure waste when CONFIG_SWAP is not set - I have never spattered around
the ifdefs to prevent that, preferring this move to sharing the common
radix tree instead.

There are three downsides to sharing the radix tree.  One, that it binds
tmpfs more tightly to the rest of mm, either requiring knowledge of swap
entries in radix tree there, or duplication of its code here in shmem.c.
I believe that the simplications and memory savings (and probable higher
performance, not yet measured) justify that.

Two, that on HIGHMEM systems with SWAP enabled, it's the lowmem radix
nodes that cannot be freed under memory pressure - whereas before it was
the less precious highmem swap vector pages that could not be freed.
I'm hoping that 64-bit has now been accessible for long enough, that the
highmem argument has grown much less persuasive.

Three, that swapoff is slower than it used to be on tmpfs files, since
it's using a simple generic mechanism not tailored to it: I find this
noticeable, and shall want to improve, but maybe nobody else will
notice.

So...  now remove most of the old swap vector code from shmem.c.  But,
for the moment, keep the simple i_direct vector of 16 pages, with simple
accessors shmem_put_swap() and shmem_get_swap(), as a toy implementation
to help mark where swap needs to be handled in subsequent patches.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:23 -10:00
Hugh Dickins a2c16d6cb0 mm: let swap use exceptional entries
If swap entries are to be stored along with struct page pointers in a
radix tree, they need to be distinguished as exceptional entries.

Most of the handling of swap entries in radix tree will be contained in
shmem.c, but a few functions in filemap.c's common code need to check
for their appearance: find_get_page(), find_lock_page(),
find_get_pages() and find_get_pages_contig().

So as not to slow their fast paths, tuck those checks inside the
existing checks for unlikely radix_tree_deref_slot(); except for
find_lock_page(), where it is an added test.  And make it a BUG in
find_get_pages_tag(), which is not applied to tmpfs files.

A part of the reason for eliminating shmem_readpage() earlier, was to
minimize the places where common code would need to allow for swap
entries.

The swp_entry_t known to swapfile.c must be massaged into a slightly
different form when stored in the radix tree, just as it gets massaged
into a pte_t when stored in page tables.

In an i386 kernel this limits its information (type and page offset) to
30 bits: given 32 "types" of swapfile and 4kB pagesize, that's a maximum
swapfile size of 128GB.  Which is less than the 512GB we previously
allowed with X86_PAE (where the swap entry can occupy the entire upper
32 bits of a pte_t), but not a new limitation on 32-bit without PAE; and
there's not a new limitation on 64-bit (where swap filesize is already
limited to 16TB by a 32-bit page offset).  Thirty areas of 128GB is
probably still enough swap for a 64GB 32-bit machine.

Provide swp_to_radix_entry() and radix_to_swp_entry() conversions, and
enforce filesize limit in read_swap_header(), just as for ptes.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:22 -10:00
Hugh Dickins 6328650bb4 radix_tree: exceptional entries and indices
A patchset to extend tmpfs to MAX_LFS_FILESIZE by abandoning its
peculiar swap vector, instead keeping a file's swap entries in the same
radix tree as its struct page pointers: thus saving memory, and
simplifying its code and locking.

This patch:

The radix_tree is used by several subsystems for different purposes.  A
major use is to store the struct page pointers of a file's pagecache for
memory management.  But what if mm wanted to store something other than
page pointers there too?

The low bit of a radix_tree entry is already used to denote an indirect
pointer, for internal use, and the unlikely radix_tree_deref_retry()
case.

Define the next bit as denoting an exceptional entry, and supply inline
functions radix_tree_exception() to return non-0 in either unlikely
case, and radix_tree_exceptional_entry() to return non-0 in the second
case.

If a subsystem already uses radix_tree with that bit set, no problem: it
does not affect internal workings at all, but is defined for the
convenience of those storing well-aligned pointers in the radix_tree.

The radix_tree_gang_lookups have an implicit assumption that the caller
can deduce the offset of each entry returned e.g.  by the page->index of
a struct page.  But that may not be feasible for some kinds of item to
be stored there.

radix_tree_gang_lookup_slot() allow for an optional indices argument,
output array in which to return those offsets.  The same could be added
to other radix_tree_gang_lookups, but for now keep it to the only one
for which we need it.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:22 -10:00
Akinobu Mita dd48c085c1 fault-injection: add ability to export fault_attr in arbitrary directory
init_fault_attr_dentries() is used to export fault_attr via debugfs.
But it can only export it in debugfs root directory.

Per Forlin is working on mmc_fail_request which adds support to inject
data errors after a completed host transfer in MMC subsystem.

The fault_attr for mmc_fail_request should be defined per mmc host and
export it in debugfs directory per mmc host like
/sys/kernel/debug/mmc0/mmc_fail_request.

init_fault_attr_dentries() doesn't help for mmc_fail_request.  So this
introduces fault_create_debugfs_attr() which is able to create a
directory in the arbitrary directory and replace
init_fault_attr_dentries().

[akpm@linux-foundation.org: extraneous semicolon, per Randy]
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Tested-by: Per Forlin <per.forlin@linaro.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-03 14:25:20 -10:00
Len Brown d0e323b470 Merge branch 'apei' into apei-release
Some trivial conflicts due to other various merges
adding to the end of common lists sooner than this one.

	arch/ia64/Kconfig
	arch/powerpc/Kconfig
	arch/x86/Kconfig
	lib/Kconfig
	lib/Makefile

Signed-off-by: Len Brown <len.brown@intel.com>
2011-08-03 11:30:42 -04:00
Huang Ying ea8f5fb8a7 HWPoison: add memory_failure_queue()
memory_failure() is the entry point for HWPoison memory error
recovery.  It must be called in process context.  But commonly
hardware memory errors are notified via MCE or NMI, so some delayed
execution mechanism must be used.  In MCE handler, a work queue + ring
buffer mechanism is used.

In addition to MCE, now APEI (ACPI Platform Error Interface) GHES
(Generic Hardware Error Source) can be used to report memory errors
too.  To add support to APEI GHES memory recovery, a mechanism similar
to that of MCE is implemented.  memory_failure_queue() is the new
entry point that can be called in IRQ context.  The next step is to
make MCE handler uses this interface too.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
2011-08-03 11:15:58 -04:00
Oleg Nesterov c027a474a6 oom: task->mm == NULL doesn't mean the memory was freed
exit_mm() sets ->mm == NULL then it does mmput()->exit_mmap() which
frees the memory.

However select_bad_process() checks ->mm != NULL before TIF_MEMDIE,
so it continues to kill other tasks even if we have the oom-killed
task freeing its memory.

Change select_bad_process() to check ->mm after TIF_MEMDIE, but skip
the tasks which have already passed exit_notify() to ensure a zombie
with TIF_MEMDIE set can't block oom-killer. Alternatively we could
probably clear TIF_MEMDIE after exit_mmap().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-01 15:24:12 -10:00
Linus Torvalds 6581058f44 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6:
  slab: use NUMA_NO_NODE
  slab: remove one NR_CPUS dependency
2011-07-31 06:25:37 -10:00
Sebastian Andrzej Siewior ffc79d2880 slub: use print_hex_dump
Less code and same functionality. The output would be:

| Object c7428000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
| Object c7428010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
| Object c7428020: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
| Object c7428030: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5              kkkkkkkkkkk.
| Redzone c742803c: bb bb bb bb                                      ....
| Padding c7428064: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a  ZZZZZZZZZZZZZZZZ
| Padding c7428074: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a              ZZZZZZZZZZZZ

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-31 19:16:48 +03:00
Sebastian Andrzej Siewior fdde6abb3e slab: use print_hex_dump
Less code and the advantage of ascii dump.

before:
| Slab corruption: names_cache start=c5788000, len=4096
| 000: 6b 6b 01 00 00 00 56 00 00 00 24 00 00 00 2a 00
| 010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
| 020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff
| 030: ff ff ff ff e2 b4 17 18 c7 e4 08 06 00 01 08 00
| 040: 06 04 00 01 e2 b4 17 18 c7 e4 0a 00 00 01 00 00
| 050: 00 00 00 00 0a 00 00 02 6b 6b 6b 6b 6b 6b 6b 6b

after:
| Slab corruption: size-4096 start=c38a9000, len=4096
| 000: 6b 6b 01 00 00 00 56 00 00 00 24 00 00 00 2a 00  kk....V...$...*.
| 010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
| 020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff  ................
| 030: ff ff ff ff d2 56 5f aa db 9c 08 06 00 01 08 00  .....V_.........
| 040: 06 04 00 01 d2 56 5f aa db 9c 0a 00 00 01 00 00  .....V_.........
| 050: 00 00 00 00 0a 00 00 02 6b 6b 6b 6b 6b 6b 6b 6b  ........kkkkkkkk

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-31 19:16:33 +03:00
Andrew Morton eacbbae385 slab: use NUMA_NO_NODE
Use the nice enumerated constant.

Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-31 18:14:21 +03:00
Linus Torvalds c11abbbaa3 Merge branch 'slub/lockless' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6
* 'slub/lockless' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6: (21 commits)
  slub: When allocating a new slab also prep the first object
  slub: disable interrupts in cmpxchg_double_slab when falling back to pagelock
  Avoid duplicate _count variables in page_struct
  Revert "SLUB: Fix build breakage in linux/mm_types.h"
  SLUB: Fix build breakage in linux/mm_types.h
  slub: slabinfo update for cmpxchg handling
  slub: Not necessary to check for empty slab on load_freelist
  slub: fast release on full slab
  slub: Add statistics for the case that the current slab does not match the node
  slub: Get rid of the another_slab label
  slub: Avoid disabling interrupts in free slowpath
  slub: Disable interrupts in free_debug processing
  slub: Invert locking and avoid slab lock
  slub: Rework allocator fastpaths
  slub: Pass kmem_cache struct to lock and freeze slab
  slub: explicit list_lock taking
  slub: Add cmpxchg_double_slab()
  mm: Rearrange struct page
  slub: Move page->frozen handling near where the page->freelist handling occurs
  slub: Do not use frozen page flag but a bit in the page counters
  ...
2011-07-30 08:21:48 -10:00
Eric Dumazet acfe7d7448 slab: remove one NR_CPUS dependency
Reduce high order allocations in do_tune_cpucache() for some setups.
(NR_CPUS=4096 -> we need 64KB)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-28 13:40:08 +03:00
Arun Sharma 60063497a9 atomic: use <linux/atomic.h>
This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>

Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:47 -07:00
Akinobu Mita b2588c4b4c fail_page_alloc: simplify debugfs initialization
Now cleanup_fault_attr_dentries() recursively removes a directory, So we
can simplify the error handling in the initialization code and no need
to hold dentry structs for each debugfs file.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:46 -07:00
Akinobu Mita 810f09b87b failslab: simplify debugfs initialization
Now cleanup_fault_attr_dentries() recursively removes a directory, So we
can simplify the error handling in the initialization code and no need
to hold dentry structs for each debugfs file.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:46 -07:00
Akinobu Mita 7f5ddcc8d3 fault-injection: use debugfs_remove_recursive
Use debugfs_remove_recursive() to simplify initialization and
deinitialization of fault injection debugfs files.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:46 -07:00
Michal Hocko 778d3b0ff0 cpusets: randomize node rotor used in cpuset_mem_spread_node()
[ This patch has already been accepted as commit 0ac0c0d0f8 but later
  reverted (commit 35926ff5fb) because it itroduced arch specific
  __node_random which was defined only for x86 code so it broke other
  archs.  This is a followup without any arch specific code.  Other than
  that there are no functional changes.]

Some workloads that create a large number of small files tend to assign
too many pages to node 0 (multi-node systems).  Part of the reason is
that the rotor (in cpuset_mem_spread_node()) used to assign nodes starts
at node 0 for newly created tasks.

This patch changes the rotor to be initialized to a random node number
of the cpuset.

[akpm@linux-foundation.org: fix layout]
[Lee.Schermerhorn@hp.com: Define stub numa_random() for !NUMA configuration]
[mhocko@suse.cz: Make it arch independent]
[akpm@linux-foundation.org: fix CONFIG_NUMA=y, MAX_NUMNODES>1 build]
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Paul Menage <menage@google.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Paul Menage <menage@google.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Robin Holt <holt@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:43 -07:00
Michal Hocko 8521fc50d4 memcg: get rid of percpu_charge_mutex lock
percpu_charge_mutex protects from multiple simultaneous per-cpu charge
caches draining because we might end up having too many work items.  At
least this was the case until commit 26fe616844 ("memcg: fix percpu
cached charge draining frequency") when we introduced a more targeted
draining for async mode.

Now that also sync draining is targeted we can safely remove mutex
because we will not send more work than the current number of CPUs.
FLUSHING_CACHED_CHARGE protects from sending the same work multiple
times and stock->nr_pages == 0 protects from pointless sending a work if
there is obviously nothing to be done.  This is of course racy but we
can live with it as the race window is really small (we would have to
see FLUSHING_CACHED_CHARGE cleared while nr_pages would be still
non-zero).

The only remaining place where we can race is synchronous mode when we
rely on FLUSHING_CACHED_CHARGE test which might have been set by other
drainer on the same group but we should wait in that case as well.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:43 -07:00
Michal Hocko 3e92041d68 memcg: add mem_cgroup_same_or_subtree() helper
We are checking whether a given two groups are same or at least in the
same subtree of a hierarchy at several places.  Let's make a helper for
it to make code easier to read.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:43 -07:00
Michal Hocko d38144b7a5 memcg: unify sync and async per-cpu charge cache draining
Currently we have two ways how to drain per-CPU caches for charges.
drain_all_stock_sync will synchronously drain all caches while
drain_all_stock_async will asynchronously drain only those that refer to
a given memory cgroup or its subtree in hierarchy.  Targeted async
draining has been introduced by 26fe6168 (memcg: fix percpu cached
charge draining frequency) to reduce the cpu workers number.

sync draining is currently triggered only from mem_cgroup_force_empty
which is triggered only by userspace (mem_cgroup_force_empty_write) or
when a cgroup is removed (mem_cgroup_pre_destroy).  Although these are
not usually frequent operations it still makes some sense to do targeted
draining as well, especially if the box has many CPUs.

This patch unifies both methods to use the single code (drain_all_stock)
which relies on the original async implementation and just adds
flush_work to wait on all caches that are still under work for the sync
mode.  We are using FLUSHING_CACHED_CHARGE bit check to prevent from
waiting on a work that we haven't triggered.  Please note that both sync
and async functions are currently protected by percpu_charge_mutex so we
cannot race with other drainers.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:42 -07:00
Michal Hocko d1a05b6973 memcg: do not try to drain per-cpu caches without pages
drain_all_stock_async tries to optimize a work to be done on the work
queue by excluding any work for the current CPU because it assumes that
the context we are called from already tried to charge from that cache
and it's failed so it must be empty already.

While the assumption is correct we can optimize it even more by checking
the current number of pages in the cache.  This will also reduce a work
on other CPUs with an empty stock.

For the current CPU we can simply call drain_local_stock rather than
deferring it to the work queue.

[kamezawa.hiroyu@jp.fujitsu.com: use drain_local_stock for current CPU optimization]
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:42 -07:00
KAMEZAWA Hiroyuki 82f9d486e5 memcg: add memory.vmscan_stat
The commit log of 0ae5e89c60 ("memcg: count the soft_limit reclaim
in...") says it adds scanning stats to memory.stat file.  But it doesn't
because we considered we needed to make a concensus for such new APIs.

This patch is a trial to add memory.scan_stat. This shows
  - the number of scanned pages(total, anon, file)
  - the number of rotated pages(total, anon, file)
  - the number of freed pages(total, anon, file)
  - the number of elaplsed time (including sleep/pause time)

  for both of direct/soft reclaim.

The biggest difference with oringinal Ying's one is that this file
can be reset by some write, as

  # echo 0 ...../memory.scan_stat

Example of output is here. This is a result after make -j 6 kernel
under 300M limit.

  [kamezawa@bluextal ~]$ cat /cgroup/memory/A/memory.scan_stat
  [kamezawa@bluextal ~]$ cat /cgroup/memory/A/memory.vmscan_stat
  scanned_pages_by_limit 9471864
  scanned_anon_pages_by_limit 6640629
  scanned_file_pages_by_limit 2831235
  rotated_pages_by_limit 4243974
  rotated_anon_pages_by_limit 3971968
  rotated_file_pages_by_limit 272006
  freed_pages_by_limit 2318492
  freed_anon_pages_by_limit 962052
  freed_file_pages_by_limit 1356440
  elapsed_ns_by_limit 351386416101
  scanned_pages_by_system 0
  scanned_anon_pages_by_system 0
  scanned_file_pages_by_system 0
  rotated_pages_by_system 0
  rotated_anon_pages_by_system 0
  rotated_file_pages_by_system 0
  freed_pages_by_system 0
  freed_anon_pages_by_system 0
  freed_file_pages_by_system 0
  elapsed_ns_by_system 0
  scanned_pages_by_limit_under_hierarchy 9471864
  scanned_anon_pages_by_limit_under_hierarchy 6640629
  scanned_file_pages_by_limit_under_hierarchy 2831235
  rotated_pages_by_limit_under_hierarchy 4243974
  rotated_anon_pages_by_limit_under_hierarchy 3971968
  rotated_file_pages_by_limit_under_hierarchy 272006
  freed_pages_by_limit_under_hierarchy 2318492
  freed_anon_pages_by_limit_under_hierarchy 962052
  freed_file_pages_by_limit_under_hierarchy 1356440
  elapsed_ns_by_limit_under_hierarchy 351386416101
  scanned_pages_by_system_under_hierarchy 0
  scanned_anon_pages_by_system_under_hierarchy 0
  scanned_file_pages_by_system_under_hierarchy 0
  rotated_pages_by_system_under_hierarchy 0
  rotated_anon_pages_by_system_under_hierarchy 0
  rotated_file_pages_by_system_under_hierarchy 0
  freed_pages_by_system_under_hierarchy 0
  freed_anon_pages_by_system_under_hierarchy 0
  freed_file_pages_by_system_under_hierarchy 0
  elapsed_ns_by_system_under_hierarchy 0

total_xxxx is for hierarchy management.

This will be useful for further memcg developments and need to be
developped before we do some complicated rework on LRU/softlimit
management.

This patch adds a new struct memcg_scanrecord into scan_control struct.
sc->nr_scanned at el is not designed for exporting information.  For
example, nr_scanned is reset frequentrly and incremented +2 at scanning
mapped pages.

To avoid complexity, I added a new param in scan_control which is for
exporting scanning score.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Cc: Andrew Bresticker <abrestic@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:42 -07:00
Daisuke Nishimura 108b6a7846 memcg: fix behavior of mem_cgroup_resize_limit()
Commit 22a668d7c3 ("memcg: fix behavior under memory.limit equals to
memsw.limit") introduced "memsw_is_minimum" flag, which becomes true
when mem_limit == memsw_limit.  The flag is checked at the beginning of
reclaim, and "noswap" is set if the flag is true, because using swap is
meaningless in this case.

This works well in most cases, but when we try to shrink mem_limit,
which is the same as memsw_limit now, we might fail to shrink mem_limit
because swap doesn't used.

This patch fixes this behavior by:
 - check MEM_CGROUP_RECLAIM_SHRINK at the begining of reclaim
 - If it is set, don't set "noswap" flag even if memsw_is_minimum is true.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:42 -07:00
KAMEZAWA Hiroyuki 4508378b95 memcg: fix vmscan count in small memcgs
Commit 246e87a939 ("memcg: fix get_scan_count() for small targets")
fixes the memcg/kswapd behavior against small targets and prevent vmscan
priority too high.

But the implementation is too naive and adds another problem to small
memcg.  It always force scan to 32 pages of file/anon and doesn't handle
swappiness and other rotate_info.  It makes vmscan to scan anon LRU
regardless of swappiness and make reclaim bad.  This patch fixes it by
adjusting scanning count with regard to swappiness at el.

At a test "cat 1G file under 300M limit." (swappiness=20)
 before patch
        scanned_pages_by_limit 360919
        scanned_anon_pages_by_limit 180469
        scanned_file_pages_by_limit 180450
        rotated_pages_by_limit 31
        rotated_anon_pages_by_limit 25
        rotated_file_pages_by_limit 6
        freed_pages_by_limit 180458
        freed_anon_pages_by_limit 19
        freed_file_pages_by_limit 180439
        elapsed_ns_by_limit 429758872
 after patch
        scanned_pages_by_limit 180674
        scanned_anon_pages_by_limit 24
        scanned_file_pages_by_limit 180650
        rotated_pages_by_limit 35
        rotated_anon_pages_by_limit 24
        rotated_file_pages_by_limit 11
        freed_pages_by_limit 180634
        freed_anon_pages_by_limit 0
        freed_file_pages_by_limit 180634
        elapsed_ns_by_limit 367119089
        scanned_pages_by_system 0

the numbers of scanning anon are decreased(as expected), and elapsed time
reduced. By this patch, small memcgs will work better.
(*) Because the amount of file-cache is much bigger than anon,
    recalaim_stat's rotate-scan counter make scanning files more.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:42 -07:00
Michal Hocko 1af8efe965 memcg: change memcg_oom_mutex to spinlock
memcg_oom_mutex is used to protect memcg OOM path and eventfd interface
for oom_control.  None of the critical sections which it protects sleep
(eventfd_signal works from atomic context and the rest are simple linked
list resp.  oom_lock atomic operations).

Mutex is also too heavyweight for those code paths because it triggers a
lot of scheduling.  It also makes makes convoying effects more visible
when we have a big number of oom killing because we take the lock
mutliple times during mem_cgroup_handle_oom so we have multiple places
where many processes can sleep.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:42 -07:00
Michal Hocko 79dfdaccd1 memcg: make oom_lock 0 and 1 based rather than counter
Commit 867578cb ("memcg: fix oom kill behavior") introduced a oom_lock
counter which is incremented by mem_cgroup_oom_lock when we are about to
handle memcg OOM situation.  mem_cgroup_handle_oom falls back to a sleep
if oom_lock > 1 to prevent from multiple oom kills at the same time.
The counter is then decremented by mem_cgroup_oom_unlock called from the
same function.

This works correctly but it can lead to serious starvations when we have
many processes triggering OOM and many CPUs available for them (I have
tested with 16 CPUs).

Consider a process (call it A) which gets the oom_lock (the first one
that got to mem_cgroup_handle_oom and grabbed memcg_oom_mutex) and other
processes that are blocked on the mutex.  While A releases the mutex and
calls mem_cgroup_out_of_memory others will wake up (one after another)
and increase the counter and fall into sleep (memcg_oom_waitq).

Once A finishes mem_cgroup_out_of_memory it takes the mutex again and
decreases oom_lock and wakes other tasks (if releasing memory by
somebody else - e.g.  killed process - hasn't done it yet).

A testcase would look like:
  Assume malloc XXX is a program allocating XXX Megabytes of memory
  which touches all allocated pages in a tight loop
  # swapoff SWAP_DEVICE
  # cgcreate -g memory:A
  # cgset -r memory.oom_control=0   A
  # cgset -r memory.limit_in_bytes= 200M
  # for i in `seq 100`
  # do
  #     cgexec -g memory:A   malloc 10 &
  # done

The main problem here is that all processes still race for the mutex and
there is no guarantee that we will get counter back to 0 for those that
got back to mem_cgroup_handle_oom.  In the end the whole convoy
in/decreases the counter but we do not get to 1 that would enable
killing so nothing useful can be done.  The time is basically unbounded
because it highly depends on scheduling and ordering on mutex (I have
seen this taking hours...).

This patch replaces the counter by a simple {un}lock semantic.  As
mem_cgroup_oom_{un}lock works on the a subtree of a hierarchy we have to
make sure that nobody else races with us which is guaranteed by the
memcg_oom_mutex.

We have to be careful while locking subtrees because we can encounter a
subtree which is already locked: hierarchy:

          A
        /   \
       B     \
      /\      \
     C  D     E

B - C - D tree might be already locked.  While we want to enable locking
E subtree because OOM situations cannot influence each other we
definitely do not want to allow locking A.

Therefore we have to refuse lock if any subtree is already locked and
clear up the lock for all nodes that have been set up to the failure
point.

On the other hand we have to make sure that the rest of the world will
recognize that a group is under OOM even though it doesn't have a lock.
Therefore we have to introduce under_oom variable which is incremented
and decremented for the whole subtree when we enter resp.  leave
mem_cgroup_handle_oom.  under_oom, unlike oom_lock, doesn't need be
updated under memcg_oom_mutex because its users only check a single
group and they use atomic operations for that.

This can be checked easily by the following test case:

  # cgcreate -g memory:A
  # cgset -r memory.use_hierarchy=1 A
  # cgset -r memory.oom_control=1   A
  # cgset -r memory.limit_in_bytes= 100M
  # cgset -r memory.memsw.limit_in_bytes= 100M
  # cgcreate -g memory:A/B
  # cgset -r memory.oom_control=1 A/B
  # cgset -r memory.limit_in_bytes=20M
  # cgset -r memory.memsw.limit_in_bytes=20M
  # cgexec -g memory:A/B malloc 30  &    #->this will be blocked by OOM of group B
  # cgexec -g memory:A   malloc 80  &    #->this will be blocked by OOM of group A

While B gets oom_lock A will not get it.  Both of them go into sleep and
wait for an external action.  We can make the limit higher for A to
enforce waking it up

  # cgset -r memory.memsw.limit_in_bytes=300M A
  # cgset -r memory.limit_in_bytes=300M A

malloc in A has to wake up even though it doesn't have oom_lock.

Finally, the unlock path is very easy because we always unlock only the
subtree we have locked previously while we always decrement under_oom.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:42 -07:00
KAMEZAWA Hiroyuki bb2a0de92c memcg: consolidate memory cgroup lru stat functions
In mm/memcontrol.c, there are many lru stat functions as..

  mem_cgroup_zone_nr_lru_pages
  mem_cgroup_node_nr_file_lru_pages
  mem_cgroup_nr_file_lru_pages
  mem_cgroup_node_nr_anon_lru_pages
  mem_cgroup_nr_anon_lru_pages
  mem_cgroup_node_nr_unevictable_lru_pages
  mem_cgroup_nr_unevictable_lru_pages
  mem_cgroup_node_nr_lru_pages
  mem_cgroup_nr_lru_pages
  mem_cgroup_get_local_zonestat

Some of them are under #ifdef MAX_NUMNODES >1 and others are not.
This seems bad. This patch consolidates all functions into

  mem_cgroup_zone_nr_lru_pages()
  mem_cgroup_node_nr_lru_pages()
  mem_cgroup_nr_lru_pages()

For these functions, "which LRU?" information is passed by a mask.

example:
  mem_cgroup_nr_lru_pages(mem, BIT(LRU_ACTIVE_ANON))

And I added some macro as ALL_LRU, ALL_LRU_FILE, ALL_LRU_ANON.

example:
  mem_cgroup_nr_lru_pages(mem, ALL_LRU)

BTW, considering layout of NUMA memory placement of counters, this patch seems
to be better.

Now, when we gather all LRU information, we scan in following orer
    for_each_lru -> for_each_node -> for_each_zone.

This means we'll touch cache lines in different node in turn.

After patch, we'll scan
    for_each_node -> for_each_zone -> for_each_lru(mask)

Then, we'll gather information in the same cacheline at once.

[akpm@linux-foundation.org: fix warnigns, build error]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:42 -07:00
KAMEZAWA Hiroyuki 1f4c025b5a memcg: export memory cgroup's swappiness with mem_cgroup_swappiness()
Each memory cgroup has a 'swappiness' value which can be accessed by
get_swappiness(memcg).  The major user is try_to_free_mem_cgroup_pages()
and swappiness is passed by argument.  It's propagated by scan_control.

get_swappiness() is a static function but some planned updates will need
to get swappiness from files other than memcontrol.c This patch exports
get_swappiness() as mem_cgroup_swappiness().  With this, we can remove the
argument of swapiness from try_to_free...  and drop swappiness from
scan_control.  only memcg uses it.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:42 -07:00
Linus Torvalds f01ef569cd Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback: (27 commits)
  mm: properly reflect task dirty limits in dirty_exceeded logic
  writeback: don't busy retry writeback on new/freeing inodes
  writeback: scale IO chunk size up to half device bandwidth
  writeback: trace global_dirty_state
  writeback: introduce max-pause and pass-good dirty limits
  writeback: introduce smoothed global dirty limit
  writeback: consolidate variable names in balance_dirty_pages()
  writeback: show bdi write bandwidth in debugfs
  writeback: bdi write bandwidth estimation
  writeback: account per-bdi accumulated written pages
  writeback: make writeback_control.nr_to_write straight
  writeback: skip tmpfs early in balance_dirty_pages_ratelimited_nr()
  writeback: trace event writeback_queue_io
  writeback: trace event writeback_single_inode
  writeback: remove .nonblocking and .encountered_congestion
  writeback: remove writeback_control.more_io
  writeback: skip balance_dirty_pages() for in-memory fs
  writeback: add bdi_dirty_limit() kernel-doc
  writeback: avoid extra sync work at enqueue time
  writeback: elevate queue_io() into wb_writeback()
  ...

Fix up trivial conflicts in fs/fs-writeback.c and mm/filemap.c
2011-07-26 10:39:54 -07:00
Linus Torvalds 45b583b10a Merge 'akpm' patch series
* Merge akpm patch series: (122 commits)
  drivers/connector/cn_proc.c: remove unused local
  Documentation/SubmitChecklist: add RCU debug config options
  reiserfs: use hweight_long()
  reiserfs: use proper little-endian bitops
  pnpacpi: register disabled resources
  drivers/rtc/rtc-tegra.c: properly initialize spinlock
  drivers/rtc/rtc-twl.c: check return value of twl_rtc_write_u8() in twl_rtc_set_time()
  drivers/rtc: add support for Qualcomm PMIC8xxx RTC
  drivers/rtc/rtc-s3c.c: support clock gating
  drivers/rtc/rtc-mpc5121.c: add support for RTC on MPC5200
  init: skip calibration delay if previously done
  misc/eeprom: add eeprom access driver for digsy_mtc board
  misc/eeprom: add driver for microwire 93xx46 EEPROMs
  checkpatch.pl: update $logFunctions
  checkpatch: make utf-8 test --strict
  checkpatch.pl: add ability to ignore various messages
  checkpatch: add a "prefer __aligned" check
  checkpatch: validate signature styles and To: and Cc: lines
  checkpatch: add __rcu as a sparse modifier
  checkpatch: suggest using min_t or max_t
  ...

Did this as a merge because of (trivial) conflicts in
 - Documentation/feature-removal-schedule.txt
 - arch/xtensa/include/asm/uaccess.h
that were just easier to fix up in the merge than in the patch series.
2011-07-25 21:00:19 -07:00
Maxin B John ae891a1b93 devres: fix possible use after free
devres uses the pointer value as key after it's freed, which is safe but
triggers spurious use-after-free warnings on some static analysis tools.
Rearrange code to avoid such warnings.

Signed-off-by: Maxin B. John <maxin.john@gmail.com>
Reviewed-by: Rolf Eike Beer <eike-kernel@sf-tec.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:14 -07:00
Wu Fengguang 99b12e3d88 writeback: account NR_WRITTEN at IO completion time
NR_WRITTEN is now accounted at block IO enqueue time, which is not very
accurate as to common understanding.  This moves NR_WRITTEN accounting to
the IO completion time and makes it more consistent with BDI_WRITTEN,
which is used for bandwidth estimation.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Michael Rubin <mrubin@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Hugh Dickins 48f170fb7d tmpfs: simplify unuse and writepage
shmem_unuse_inode() and shmem_writepage() contain a little code to cope
with pages inserted independently into the filecache, probably by a
filesystem stacked on top of tmpfs, then fed to its ->readpage() or
->writepage().

Unionfs was indeed experimenting with working in that way three years ago,
but I find no current examples: nowadays the stacking filesystems use vfs
interfaces to the lower filesystem.

It's now illegal: remove most of that code, adding some WARN_ON_ONCEs.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Erez Zadok <ezk@fsl.cs.sunysb.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Hugh Dickins 27ab700626 tmpfs: simplify filepage/swappage
We can now simplify shmem_getpage_gfp(): there is no longer a dilemma of
filepage passed in via shmem_readpage(), then swappage found, which must
then be copied over to it.

Although at first it's tempting to replace the **pagep arg by returning
struct page *, that makes a mess of IS_ERR_OR_NULL(page)s in all the
callers, so leave as is.

Insert BUG_ON(!PageUptodate) when we find and lock page: some of the
complication came from uninitialized pages inserted into filecache prior
to readpage; but now we're in control, and only release pagelock on
filecache once it's uptodate (if an error occurs in reading back from
swap, the page remains in swapcache, never moved to filecache).

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Hugh Dickins e83c32e8f9 tmpfs: simplify prealloc_page
The prealloc_page handling in shmem_getpage_gfp() is unnecessarily
complicated: first simplify that before going on to filepage/swappage.

That's right, don't report ENOMEM when the preallocation fails: we may or
may not need the page.  But simply report ENOMEM once we find we do need
it, instead of dropping lock, repeating allocation, unwinding on failure
etc.  And leave the out label on the fast path, don't goto.

Fix something that looks like a bug but turns out not to be: set
PageSwapBacked on prealloc_page before its mem_cgroup_cache_charge(), as
the removed case was doing.  That's important before adding to LRU
(determines which LRU the page goes on), and does affect which path it
takes through memcontrol.c, but in the end MEM_CGROUP_CHANGE_TYPE_ SHMEM
is handled no differently from CACHE.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Shaohua Li <shaohua.li@intel.com>
Cc: "Zhang, Yanmin" <yanmin.zhang@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Hugh Dickins 9276aad6c8 tmpfs: remove_shmem_readpage
Remove that pernicious shmem_readpage() at last: the things we needed it
for (splice, loop, sendfile, i915 GEM) are now fully taken care of by
shmem_file_splice_read() and shmem_read_mapping_page_gfp().

This removal clears the way for a simpler shmem_getpage_gfp(), since page
is never passed in; but leave most of that cleanup until after.

sys_readahead() and sys_fadvise(POSIX_FADV_WILLNEED) will now EINVAL,
instead of unexpectedly trying to read ahead on tmpfs: if that proves to
be an issue for someone, then we can either arrange for them to return
success instead, or try to implement async readahead on tmpfs.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Hugh Dickins 68da9f0557 tmpfs: pass gfp to shmem_getpage_gfp
Make shmem_getpage() a wrapper, passing mapping_gfp_mask() down to
shmem_getpage_gfp(), which in turn passes gfp down to shmem_swp_alloc().

Change shmem_read_mapping_page_gfp() to use shmem_getpage_gfp() in the
CONFIG_SHMEM case; but leave tiny !SHMEM using read_cache_page_gfp().

Add a BUG_ON() in case anyone happens to call this on a non-shmem mapping;
though we might later want to let that case route to read_cache_page_gfp().

It annoys me to have these two almost-redundant args, gfp and fault_type:
I can't find a better way; but initialize fault_type only in shmem_fault().

Note that before, read_cache_page_gfp() was allocating i915_gem's pages
with __GFP_NORETRY as intended; but the corresponding swap vector pages
got allocated without it, leaving a small possibility of OOM.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Hugh Dickins 71f0e07a60 tmpfs: refine shmem_file_splice_read
Tidy up shmem_file_splice_read():

Remove readahead: okay, we could implement shmem readahead on swap,
but have never done so before, swap being the slow exceptional path.

Use shmem_getpage() instead of find_or_create_page() plus ->readpage().

Remove several comments: sorry, I found them more distracting than
helpful, and this will not be the reference version of splice_read().

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Hugh Dickins 708e3508c2 tmpfs: clone shmem_file_splice_read()
Copy __generic_file_splice_read() and generic_file_splice_read() from
fs/splice.c to shmem_file_splice_read() in mm/shmem.c.  Make
page_cache_pipe_buf_ops and spd_release_page() accessible to it.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Benjamin Herrenschmidt 2efaca927f mm/futex: fix futex writes on archs with SW tracking of dirty & young
I haven't reproduced it myself but the fail scenario is that on such
machines (notably ARM and some embedded powerpc), if you manage to hit
that futex path on a writable page whose dirty bit has gone from the PTE,
you'll livelock inside the kernel from what I can tell.

It will go in a loop of trying the atomic access, failing, trying gup to
"fix it up", getting succcess from gup, go back to the atomic access,
failing again because dirty wasn't fixed etc...

So I think you essentially hang in the kernel.

The scenario is probably rare'ish because affected architecture are
embedded and tend to not swap much (if at all) so we probably rarely hit
the case where dirty is missing or young is missing, but I think Shan has
a piece of SW that can reliably reproduce it using a shared writable
mapping & fork or something like that.

On archs who use SW tracking of dirty & young, a page without dirty is
effectively mapped read-only and a page without young unaccessible in the
PTE.

Additionally, some architectures might lazily flush the TLB when relaxing
write protection (by doing only a local flush), and expect a fault to
invalidate the stale entry if it's still present on another processor.

The futex code assumes that if the "in_atomic()" access -EFAULT's, it can
"fix it up" by causing get_user_pages() which would then be equivalent to
taking the fault.

However that isn't the case.  get_user_pages() will not call
handle_mm_fault() in the case where the PTE seems to have the right
permissions, regardless of the dirty and young state.  It will eventually
update those bits ...  in the struct page, but not in the PTE.

Additionally, it will not handle the lazy TLB flushing that can be
required by some architectures in the fault case.

Basically, gup is the wrong interface for the job.  The patch provides a
more appropriate one which boils down to just calling handle_mm_fault()
since what we are trying to do is simulate a real page fault.

The futex code currently attempts to write to user memory within a
pagefault disabled section, and if that fails, tries to fix it up using
get_user_pages().

This doesn't work on archs where the dirty and young bits are maintained
by software, since they will gate access permission in the TLB, and will
not be updated by gup().

In addition, there's an expectation on some archs that a spurious write
fault triggers a local TLB flush, and that is missing from the picture as
well.

I decided that adding those "features" to gup() would be too much for this
already too complex function, and instead added a new simpler
fixup_user_fault() which is essentially a wrapper around handle_mm_fault()
which the futex code can call.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix some nits Darren saw, fiddle comment layout]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reported-by: Shan Hai <haishan.bai@gmail.com>
Tested-by: Shan Hai <haishan.bai@gmail.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Darren Hart <darren.hart@intel.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Konstantin Khlebnikov 72c4783210 mm: remove useless rcu lock-unlock from mapping_tagged()
radix_tree_tagged() is lockless - it reads from a member of the raid-tree
root node.  It does not require any protection.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:11 -07:00
Mel Gorman 76d3fbf8fb mm: page allocator: reconsider zones for allocation after direct reclaim
With zone_reclaim_mode enabled, it's possible for zones to be considered
full in the zonelist_cache so they are skipped in the future.  If the
process enters direct reclaim, the ZLC may still consider zones to be full
even after reclaiming pages.  Reconsider all zones for allocation if
direct reclaim returns successfully.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:10 -07:00
Mel Gorman cd38b115d5 mm: page allocator: initialise ZLC for first zone eligible for zone_reclaim
There have been a small number of complaints about significant stalls
while copying large amounts of data on NUMA machines reported on a
distribution bugzilla.  In these cases, zone_reclaim was enabled by
default due to large NUMA distances.  In general, the complaints have not
been about the workload itself unless it was a file server (in which case
the recommendation was disable zone_reclaim).

The stalls are mostly due to significant amounts of time spent scanning
the preferred zone for pages to free.  After a failure, it might fallback
to another node (as zonelists are often node-ordered rather than
zone-ordered) but stall quickly again when the next allocation attempt
occurs.  In bad cases, each page allocated results in a full scan of the
preferred zone.

Patch 1 checks the preferred zone for recent allocation failure
        which is particularly important if zone_reclaim has failed
        recently.  This avoids rescanning the zone in the near future and
        instead falling back to another node.  This may hurt node locality
        in some cases but a failure to zone_reclaim is more expensive than
        a remote access.

Patch 2 clears the zlc information after direct reclaim.
        Otherwise, zone_reclaim can mark zones full, direct reclaim can
        reclaim enough pages but the zone is still not considered for
        allocation.

This was tested on a 24-thread 2-node x86_64 machine.  The tests were
focused on large amounts of IO.  All tests were bound to the CPUs on
node-0 to avoid disturbances due to processes being scheduled on different
nodes.  The kernels tested are

3.0-rc6-vanilla		Vanilla 3.0-rc6
zlcfirst		Patch 1 applied
zlcreconsider		Patches 1+2 applied

FS-Mark
./fs_mark  -d  /tmp/fsmark-10813  -D  100  -N  5000  -n  208  -L  35  -t  24  -S0  -s  524288
                fsmark-3.0-rc6       3.0-rc6       		3.0-rc6
                   vanilla			 zlcfirs 	zlcreconsider
Files/s  min          54.90 ( 0.00%)       49.80 (-10.24%)       49.10 (-11.81%)
Files/s  mean        100.11 ( 0.00%)      135.17 (25.94%)      146.93 (31.87%)
Files/s  stddev       57.51 ( 0.00%)      138.97 (58.62%)      158.69 (63.76%)
Files/s  max         361.10 ( 0.00%)      834.40 (56.72%)      802.40 (55.00%)
Overhead min       76704.00 ( 0.00%)    76501.00 ( 0.27%)    77784.00 (-1.39%)
Overhead mean    1485356.51 ( 0.00%)  1035797.83 (43.40%)  1594680.26 (-6.86%)
Overhead stddev  1848122.53 ( 0.00%)   881489.88 (109.66%)  1772354.90 ( 4.27%)
Overhead max     7989060.00 ( 0.00%)  3369118.00 (137.13%) 10135324.00 (-21.18%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds)        501.49    493.91    499.93
Total Elapsed Time (seconds)               2451.57   2257.48   2215.92

MMTests Statistics: vmstat
Page Ins                                       46268       63840       66008
Page Outs                                   90821596    90671128    88043732
Swap Ins                                           0           0           0
Swap Outs                                          0           0           0
Direct pages scanned                        13091697     8966863     8971790
Kswapd pages scanned                               0     1830011     1831116
Kswapd pages reclaimed                             0     1829068     1829930
Direct pages reclaimed                      13037777     8956828     8648314
Kswapd efficiency                               100%         99%         99%
Kswapd velocity                                0.000     810.643     826.346
Direct efficiency                                99%         99%         96%
Direct velocity                             5340.128    3972.068    4048.788
Percentage direct scans                         100%         83%         83%
Page writes by reclaim                             0           3           0
Slabs scanned                                 796672      720640      720256
Direct inode steals                          7422667     7160012     7088638
Kswapd inode steals                                0     1736840     2021238

Test completes far faster with a large increase in the number of files
created per second.  Standard deviation is high as a small number of
iterations were much higher than the mean.  The number of pages scanned by
zone_reclaim is reduced and kswapd is used for more work.

LARGE DD
               		3.0-rc6       3.0-rc6       3.0-rc6
                   	vanilla     zlcfirst     zlcreconsider
download tar           59 ( 0.00%)   59 ( 0.00%)   55 ( 7.27%)
dd source files       527 ( 0.00%)  296 (78.04%)  320 (64.69%)
delete source          36 ( 0.00%)   19 (89.47%)   20 (80.00%)
MMTests Statistics: duration
User/Sys Time Running Test (seconds)        125.03    118.98    122.01
Total Elapsed Time (seconds)                624.56    375.02    398.06

MMTests Statistics: vmstat
Page Ins                                     3594216      439368      407032
Page Outs                                   23380832    23380488    23377444
Swap Ins                                           0           0           0
Swap Outs                                          0         436         287
Direct pages scanned                        17482342    69315973    82864918
Kswapd pages scanned                               0      519123      575425
Kswapd pages reclaimed                             0      466501      522487
Direct pages reclaimed                       5858054     2732949     2712547
Kswapd efficiency                               100%         89%         90%
Kswapd velocity                                0.000    1384.254    1445.574
Direct efficiency                                33%          3%          3%
Direct velocity                            27991.453  184832.737  208171.929
Percentage direct scans                         100%         99%         99%
Page writes by reclaim                             0        5082       13917
Slabs scanned                                  17280       29952       35328
Direct inode steals                           115257     1431122      332201
Kswapd inode steals                                0           0      979532

This test downloads a large tarfile and copies it with dd a number of
times - similar to the most recent bug report I've dealt with.  Time to
completion is reduced.  The number of pages scanned directly is still
disturbingly high with a low efficiency but this is likely due to the
number of dirty pages encountered.  The figures could probably be improved
with more work around how kswapd is used and how dirty pages are handled
but that is separate work and this result is significant on its own.

Streaming Mapped Writer
MMTests Statistics: duration
User/Sys Time Running Test (seconds)        124.47    111.67    112.64
Total Elapsed Time (seconds)               2138.14   1816.30   1867.56

MMTests Statistics: vmstat
Page Ins                                       90760       89124       89516
Page Outs                                  121028340   120199524   120736696
Swap Ins                                           0          86          55
Swap Outs                                          0           0           0
Direct pages scanned                       114989363    96461439    96330619
Kswapd pages scanned                        56430948    56965763    57075875
Kswapd pages reclaimed                      27743219    27752044    27766606
Direct pages reclaimed                         49777       46884       36655
Kswapd efficiency                                49%         48%         48%
Kswapd velocity                            26392.541   31363.631   30561.736
Direct efficiency                                 0%          0%          0%
Direct velocity                            53780.091   53108.759   51581.004
Percentage direct scans                          67%         62%         62%
Page writes by reclaim                           385         122        1513
Slabs scanned                                  43008       39040       42112
Direct inode steals                                0          10           8
Kswapd inode steals                              733         534         477

This test just creates a large file mapping and writes to it linearly.
Time to completion is again reduced.

The gains are mostly down to two things.  In many cases, there is less
scanning as zone_reclaim simply gives up faster due to recent failures.
The second reason is that memory is used more efficiently.  Instead of
scanning the preferred zone every time, the allocator falls back to
another zone and uses it instead improving overall memory utilisation.

This patch: initialise ZLC for first zone eligible for zone_reclaim.

The zonelist cache (ZLC) is used among other things to record if
zone_reclaim() failed for a particular zone recently.  The intention is to
avoid a high cost scanning extremely long zonelists or scanning within the
zone uselessly.

Currently the zonelist cache is setup only after the first zone has been
considered and zone_reclaim() has been called.  The objective was to avoid
a costly setup but zone_reclaim is itself quite expensive.  If it is
failing regularly such as the first eligible zone having mostly mapped
pages, the cost in scanning and allocation stalls is far higher than the
ZLC initialisation step.

This patch initialises ZLC before the first eligible zone calls
zone_reclaim().  Once initialised, it is checked whether the zone failed
zone_reclaim recently.  If it has, the zone is skipped.  As the first zone
is now being checked, additional care has to be taken about zones marked
full.  A zone can be marked "full" because it should not have enough
unmapped pages for zone_reclaim but this is excessive as direct reclaim or
kswapd may succeed where zone_reclaim fails.  Only mark zones "full" after
zone_reclaim fails if it failed to reclaim enough pages after scanning.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:10 -07:00
KAMEZAWA Hiroyuki 1d65f86db1 mm: preallocate page before lock_page() at filemap COW
Currently we are keeping faulted page locked throughout whole __do_fault
call (except for page_mkwrite code path) after calling file system's fault
code.  If we do early COW, we allocate a new page which has to be charged
for a memcg (mem_cgroup_newpage_charge).

This function, however, might block for unbounded amount of time if memcg
oom killer is disabled or fork-bomb is running because the only way out of
the OOM situation is either an external event or OOM-situation fix.

In the end we are keeping the faulted page locked and blocking other
processes from faulting it in which is not good at all because we are
basically punishing potentially an unrelated process for OOM condition in
a different group (I have seen stuck system because of ld-2.11.1.so being
locked).

We can do test easily.

 % cgcreate -g memory:A
 % cgset -r memory.limit_in_bytes=64M A
 % cgset -r memory.memsw.limit_in_bytes=64M A
 % cd kernel_dir; cgexec -g memory:A make -j

Then, the whole system will live-locked until you kill 'make -j'
by hands (or push reboot...) This is because some important page in a
a shared library are locked.

Considering again, the new page is not necessary to be allocated
with lock_page() held. And usual page allocation may dive into
long memory reclaim loop with holding lock_page() and can cause
very long latency.

There are 3 ways.
  1. do allocation/charge before lock_page()
     Pros. - simple and can handle page allocation in the same manner.
             This will reduce holding time of lock_page() in general.
     Cons. - we do page allocation even if ->fault() returns error.

  2. do charge after unlock_page(). Even if charge fails, it's just OOM.
     Pros. - no impact to non-memcg path.
     Cons. - implemenation requires special cares of LRU and we need to modify
             page_add_new_anon_rmap()...

  3. do unlock->charge->lock again method.
     Pros. - no impact to non-memcg path.
     Cons. - This may kill LOCK_PAGE_RETRY optimization. We need to release
             lock and get it again...

This patch moves "charge" and memory allocation for COW page
before lock_page(). Then, we can avoid scanning LRU with holding
a lock on a page and latency under lock_page() will be reduced.

Then, above livelock disappears.

[akpm@linux-foundation.org: fix code layout]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reported-by: Lutz Vieweg <lvml@5t9.de>
Original-idea-by: Michal Hocko <mhocko@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:10 -07:00
Hugh Dickins d515afe88a tmpfs: no need to use i_lock
2.6.36's 7e496299d4 ("tmpfs: make tmpfs scalable with percpu_counter for
used blocks") to make tmpfs scalable with percpu_counter used
inode->i_lock in place of sbinfo->stat_lock around i_blocks updates; but
that was adverse to scalability, and unnecessary, since info->lock is
already held there in the fast paths.

Remove those uses of i_lock, and add info->lock in the three error paths
where it's then needed across shmem_free_blocks().  It's not actually
needed across shmem_unacct_blocks(), but they're so often paired that it
looks wrong to split them apart.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:10 -07:00
Hugh Dickins d0823576bf mm: pincer in truncate_inode_pages_range
truncate_inode_pages_range()'s final loop has a nice pincer property,
bringing start and end together, squeezing out the last pages.  But the
range handling missed out on that, just sliding up the range, perhaps
letting pages come in behind it.  Add one more test to give it the same
pincer effect.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:10 -07:00
Hugh Dickins b85e0effd3 mm: consistent truncate and invalidate loops
Make the pagevec_lookup loops in truncate_inode_pages_range(),
invalidate_mapping_pages() and invalidate_inode_pages2_range() more
consistent with each other.

They were relying upon page->index of an unlocked page, but apologizing
for it: accept it, embrace it, add comments and WARN_ONs, and simplify the
index handling.

invalidate_inode_pages2_range() had special handling for a wrapped
page->index + 1 = 0 case; but MAX_LFS_FILESIZE doesn't let us anywhere
near there, and a corrupt page->index in the radix_tree could cause more
trouble than that would catch.  Remove that wrapped handling.

invalidate_inode_pages2_range() uses min() to limit the pagevec_lookup
when near the end of the range: copy that into the other two, although
it's less useful than you might think (it limits the use of the buffer,
rather than the indices looked up).

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:10 -07:00
Hugh Dickins 8a549bea51 mm: tidy vmtruncate_range and related functions
Use consistent variable names in truncate_pagecache(), truncate_setsize(),
vmtruncate() and vmtruncate_range().

unmap_mapping_range() and vmtruncate_range() have mismatched interfaces:
don't change either, but make the vmtruncates more precise about what they
expect unmap_mapping_range() to do.

vmtruncate_range() is currently called only with page-aligned start and
end+1: can handle unaligned start, but unaligned end+1 would hit BUG_ON in
truncate_inode_pages_range() (lacks partial clearing of the end page).

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:10 -07:00
Hugh Dickins 5e5358e7cf mm: cleanup descriptions of filler arg
The often-NULL data arg to read_cache_page() and read_mapping_page()
functions is misdescribed as "destination for read data": no, it's the
first arg to the filler function, often struct file * to ->readpage().

Satisfy checkpatch.pl on those filler prototypes, and tidy up the
declarations in linux/pagemap.h.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:10 -07:00
Dmitry Fink c15bef3099 mmap: fix and tidy up overcommit page arithmetic
- shmem pages are not immediately available, but they are not
  potentially available either, even if we swap them out, they will just
  relocate from memory into swap, total amount of immediate and
  potentially available memory is not going to be affected, so we
  shouldn't count them as potentially free in the first place.

- nr_free_pages() is not an expensive operation anymore, there is no
  need to split the decision making in two halves and repeat code.

Signed-off-by: Dmitry Fink <dmitry.fink@palm.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:09 -07:00
Andrew Morton c9d8c3d089 mm/memblock.c: avoid abuse of RED_INACTIVE
RED_INACTIVE is a slab thing, and reusing it for memblock was
inappropriate, because memblock is dealing with phys_addr_t's which have a
Kconfigurable sizeof().

Create a new poison type for this application.  Fixes the sparse warning

    warning: cast truncates bits from constant value (9f911029d74e35b becomes 9d74e35b)

Reported-by: H Hartley Sweeten <hartleys@visionengravers.com>
Tested-by: H Hartley Sweeten <hartleys@visionengravers.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:09 -07:00
David Rientjes 11239836c0 oom: remove references to old badness() function
The badness() function in the oom killer was renamed to oom_badness() in
a63d83f427 ("oom: badness heuristic rewrite") since it is a globally
exported function for clarity.

The prototype for the old function still existed in linux/oom.h, so remove
it.  There are no existing users.

Also fixes documentation and comment references to badness() and adjusts
them accordingly.

Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:09 -07:00
Andrew Morton 6ac4752006 mm/memory.c: remove ZAP_BLOCK_SIZE
ZAP_BLOCK_SIZE became unused in the preemptible-mmu_gather work ("mm:
Remove i_mmap_lock lockbreak").  So zap it.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:09 -07:00
Chris Forbes 32f84528fb mm: hugetlb: fix coding style issues
Fix coding style issues flagged by checkpatch.pl

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Acked-by: Eric B Munson <emunson@mgebm.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:09 -07:00
Chris Wright d788e80a8c mm/huge_memory.c: minor lock simplification in __khugepaged_exit
The lock is released first thing in all three branches.  Simplify this by
unconditionally releasing lock and remove else clause which was only there
to be sure lock was released.

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:09 -07:00
Daniel Kiper 1bb36fbd4d mm/page_cgroup.c: simplify code by using SECTION_ALIGN_UP() and SECTION_ALIGN_DOWN() macros
Commit a539f3533b ("mm: add SECTION_ALIGN_UP() and
SECTION_ALIGN_DOWN() macro") introduced the SECTION_ALIGN_UP() and
SECTION_ALIGN_DOWN() macros.  Use those macros to increase code
readability.

Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:09 -07:00
WANG Cong 00a66d2974 mm: remove the leftovers of noswapaccount
In commit a2c8990aed ("memsw: remove noswapaccount kernel parameter"),
Michal forgot to remove some left pieces of noswapaccount in the tree,
this patch removes them all.

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:09 -07:00
KOSAKI Motohiro dd78553b5e pagewalk: fix code comment for THP
Commit bae9c19bf1 ("thp: split_huge_page_mm/vma") changed locking behavior
of walk_page_range().  Thus this patch changes the comment too.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:09 -07:00
KOSAKI Motohiro c27fe4c894 pagewalk: add locking-rule comments
Originally, walk_hugetlb_range() didn't require a caller take any lock.
But commit d33b9f45bd ("mm: hugetlb: fix hugepage memory leak in
walk_page_range") changed its rule.  Because it added find_vma() call in
walk_hugetlb_range().

Any locking-rule change commit should write a doc too.

[akpm@linux-foundation.org: clarify comment]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:08 -07:00
KOSAKI Motohiro 6c6d528043 pagewalk: don't look up vma if walk->hugetlb_entry is unused
Currently, walk_page_range() calls find_vma() every page table for walk
iteration.  but it's completely unnecessary if walk->hugetlb_entry is
unused.  And we don't have to assume find_vma() is a lightweight
operation.  So this patch checks the walk->hugetlb_entry and avoids the
find_vma() call if possible.

This patch also makes some cleanups.  1) remove ugly uninitialized_var()
and 2) #ifdef in function body.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:08 -07:00
KOSAKI Motohiro 4b6ddbf7ed pagewalk: fix walk_page_range() don't check find_vma() result properly
The doc of find_vma() says,

    /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
    struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
    {
     (snip)

Thus, caller should confirm whether the returned vma matches a desired one.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:08 -07:00
KOSAKI Motohiro 45ebb84025 mm: swap-token: add a comment for priority aging
Document some swap token aging design decisions.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:08 -07:00
KOSAKI Motohiro 53bb01f593 mm: swap-token: makes global variables to function local
global_faults and last_aging are only used in grab_swap_token().  Move
them into grab_swap_token().

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:08 -07:00
KOSAKI Motohiro e21c7ffd6f mm: swap-token: fix dead link
http://www.cs.wm.edu/~sjiang/token.pdf is now dead.  Replace it with an
alive alternative.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:08 -07:00
Daniel Kiper 9d0ad8ca43 mm: extend memory hotplug API to allow memory hotplug in virtual machines
This patch contains online_page_callback and apropriate functions for
registering/unregistering online page callbacks.  It allows to do some
machine specific tasks during online page stage which is required to
implement memory hotplug in virtual machines.  Currently this patch is
required by latest memory hotplug support for Xen balloon driver patch
which will be posted soon.

Additionally, originial online_page() function was splited into
following functions doing "atomic" operations:

  - __online_page_set_limits() - set new limits for memory management code,
  - __online_page_increment_counters() - increment totalram_pages and totalhigh_pages,
  - __online_page_free() - free page to allocator.

It was done to:
  - not duplicate existing code,
  - ease hotplug code devolpment by usage of well defined interface,
  - avoid stupid bugs which are unavoidable when the same code
    (by design) is developed in many places.

[akpm@linux-foundation.org: use explicit indirect-call syntax]
Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:08 -07:00
Peter Zijlstra ccb6108f5b mm/backing-dev.c: reset bdi min_ratio in bdi_unregister()
Vito said:

: The system has many usb disks coming and going day to day, with their
: respective bdi's having min_ratio set to 1 when inserted.  It works for
: some time until eventually min_ratio can no longer be set, even when the
: active set of bdi's seen in /sys/class/bdi/*/min_ratio doesn't add up to
: anywhere near 100.
:
: This then leads to an unrelated starvation problem caused by write-heavy
: fuse mounts being used atop the usb disks, a problem the min_ratio setting
: at the underlying devices bdi effectively prevents.

Fix this leakage by resetting the bdi min_ratio when unregistering the
BDI.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Reported-by: Vito Caputo <lkml@pengaru.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:07 -07:00
Ian Campbell 33dd4e0ec9 mm: make some struct page's const
These uses are read-only and in a subsequent patch I have a const struct
page in my hand...

[akpm@linux-foundation.org: fix warnings in lowmem_page_address()]
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:07 -07:00
Becky Bruce ee8f248d26 hugetlb: add phys addr to struct huge_bootmem_page
This is needed on HIGHMEM systems - we don't always have a virtual
address so store the physical address and map it in as needed.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:07 -07:00
Linus Torvalds d3ec4844d4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (43 commits)
  fs: Merge split strings
  treewide: fix potentially dangerous trailing ';' in #defined values/expressions
  uwb: Fix misspelling of neighbourhood in comment
  net, netfilter: Remove redundant goto in ebt_ulog_packet
  trivial: don't touch files that are removed in the staging tree
  lib/vsprintf: replace link to Draft by final RFC number
  doc: Kconfig: `to be' -> `be'
  doc: Kconfig: Typo: square -> squared
  doc: Konfig: Documentation/power/{pm => apm-acpi}.txt
  drivers/net: static should be at beginning of declaration
  drivers/media: static should be at beginning of declaration
  drivers/i2c: static should be at beginning of declaration
  XTENSA: static should be at beginning of declaration
  SH: static should be at beginning of declaration
  MIPS: static should be at beginning of declaration
  ARM: static should be at beginning of declaration
  rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check
  Update my e-mail address
  PCIe ASPM: forcedly -> forcibly
  gma500: push through device driver tree
  ...

Fix up trivial conflicts:
 - arch/arm/mach-ep93xx/dma-m2p.c (deleted)
 - drivers/gpio/gpio-ep93xx.c (renamed and context nearby)
 - drivers/net/r8169.c (just context changes)
2011-07-25 13:56:39 -07:00
Linus Torvalds 0003230e82 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  fs: take the ACL checks to common code
  bury posix_acl_..._masq() variants
  kill boilerplates around posix_acl_create_masq()
  generic_acl: no need to clone acl just to push it to set_cached_acl()
  kill boilerplate around posix_acl_chmod_masq()
  reiserfs: cache negative ACLs for v1 stat format
  xfs: cache negative ACLs if there is no attribute fork
  9p: do no return 0 from ->check_acl without actually checking
  vfs: move ACL cache lookup into generic code
  CIFS: Fix oops while mounting with prefixpath
  xfs: Fix wrong return value of xfs_file_aio_write
  fix devtmpfs race
  caam: don't pass bogus S_IFCHR to debugfs_create_...()
  get rid of create_proc_entry() abuses - proc_mkdir() is there for purpose
  asus-wmi: ->is_visible() can't return negative
  fix jffs2 ACLs on big-endian with 16bit mode_t
  9p: close ACL leaks
  ocfs2_init_acl(): fix a leak
  VFS : mount lock scalability for internal mounts
2011-07-25 12:53:15 -07:00
Christoph Hellwig 4e34e719e4 fs: take the ACL checks to common code
Replace the ->check_acl method with a ->get_acl method that simply reads an
ACL from disk after having a cache miss.  This means we can replace the ACL
checking boilerplate code with a single implementation in namei.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-25 14:30:23 -04:00
Christoph Lameter 9e577e8b46 slub: When allocating a new slab also prep the first object
We need to branch to the debug code for the first object if we allocate
a new slab otherwise the first object will be marked wrongly as inactive.

Tested-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-25 20:58:19 +03:00