Commit Graph

8300 Commits

Author SHA1 Message Date
Chen Yucong 50088c4409 mm/swapfile.c: delete the "last_in_cluster < scan_base" loop in the body of scan_swap_map()
Via commit ebc2a1a691 ("swap: make cluster allocation per-cpu"), we
can find that all SWP_SOLIDSTATE "seek is cheap"(SSD case) has already
gone to si->cluster_info scan_swap_map_try_ssd_cluster() route.  So that
the "last_in_cluster < scan_base" loop in the body of scan_swap_map()
has already become a dead code snippet, and it should have been deleted.

This patch is to delete the redundant loop as Hugh and Shaohua
suggested.

[hughd@google.com: fix comment, simplify code]
Signed-off-by: Chen Yucong <slaoub@gmail.com>
Cc: Shaohua Li <shli@kernel.org>
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>
2014-06-04 16:54:12 -07:00
Naoya Horiguchi 100873d7a7 hugetlb: rename hugepage_migration_support() to ..._supported()
We already have a function named hugepages_supported(), and the similar
name hugepage_migration_support() is a bit unconfortable, so let's rename
it hugepage_migration_supported().

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.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>
2014-06-04 16:54:12 -07:00
Kirill A. Shutemov 1fdb412bd8 mm: document do_fault_around() feature
Some clarification on how faultaround works.

[akpm@linux-foundation.org: tweak comment text]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:12 -07:00
Kirill A. Shutemov a9b0f8618d mm: nominate faultaround area in bytes rather than page order
There is evidencs that the faultaround feature is less relevant on
architectures with page size bigger then 4k.  Which makes sense since page
fault overhead per byte of mapped area should be less there.

Let's rework the feature to specify faultaround area in bytes instead of
page order.  It's 64 kilobytes for now.

The patch effectively disables faultaround on architectures with page size
>= 64k (like ppc64).

It's possible that some other size of faultaround area is relevant for a
platform.  We can expose `fault_around_bytes' variable to arch-specific
code once such platforms will be found.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Hugh Dickins <hughd@google.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:12 -07:00
Zhang Zhen 7d018176e6 mm/page_alloc.c: cleanup add_active_range() related comments
add_active_range() has been repalced by memblock_set_node().  Clean up the
comments to comply with that change.

Signed-off-by: Zhang Zhen <zhenzhang.zhang@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:12 -07:00
Konstantin Khlebnikov daa5ba768b mm/rmap.c: cleanup ttu_flags
Transform action part of ttu_flags into individiual bits.  These flags
aren't part of any uses-space visible api or even trace events.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:12 -07:00
Konstantin Khlebnikov 3d92860f97 mm/rmap.c: don't call mmu_notifier_invalidate_page() during munlock
In its munmap mode, try_to_unmap_one() searches other mlocked vmas, it
never unmaps pages.  There is no reason for invalidation because ptes are
left unchanged.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:12 -07:00
Konstantin Khlebnikov 226b4ccdcb mm/process_vm_access: move config option into init/Kconfig
CONFIG_CROSS_MEMORY_ATTACH adds couple syscalls: process_vm_readv and
process_vm_writev, it's a kind of IPC for copying data between processes.
Currently this option is placed inside "Processor type and features".

This patch moves it into "General setup" (where all other arch-independed
syscalls and ipc features are placed) and changes prompt string to less
cryptic.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Christopher Yeoh <cyeoh@au1.ibm.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:12 -07:00
Mel Gorman 1a501907bb mm: vmscan: use proportional scanning during direct reclaim and full scan at DEF_PRIORITY
Commit "mm: vmscan: obey proportional scanning requirements for kswapd"
ensured that file/anon lists were scanned proportionally for reclaim from
kswapd but ignored it for direct reclaim.  The intent was to minimse
direct reclaim latency but Yuanhan Liu pointer out that it substitutes one
long stall for many small stalls and distorts aging for normal workloads
like streaming readers/writers.  Hugh Dickins pointed out that a
side-effect of the same commit was that when one LRU list dropped to zero
that the entirety of the other list was shrunk leading to excessive
reclaim in memcgs.  This patch scans the file/anon lists proportionally
for direct reclaim to similarly age page whether reclaimed by kswapd or
direct reclaim but takes care to abort reclaim if one LRU drops to zero
after reclaiming the requested number of pages.

Based on ext4 and using the Intel VM scalability test

                                              3.15.0-rc5            3.15.0-rc5
                                                shrinker            proportion
Unit  lru-file-readonce    elapsed      5.3500 (  0.00%)      5.4200 ( -1.31%)
Unit  lru-file-readonce time_range      0.2700 (  0.00%)      0.1400 ( 48.15%)
Unit  lru-file-readonce time_stddv      0.1148 (  0.00%)      0.0536 ( 53.33%)
Unit lru-file-readtwice    elapsed      8.1700 (  0.00%)      8.1700 (  0.00%)
Unit lru-file-readtwice time_range      0.4300 (  0.00%)      0.2300 ( 46.51%)
Unit lru-file-readtwice time_stddv      0.1650 (  0.00%)      0.0971 ( 41.16%)

The test cases are running multiple dd instances reading sparse files. The results are within
the noise for the small test machine. The impact of the patch is more noticable from the vmstats

                            3.15.0-rc5  3.15.0-rc5
                              shrinker  proportion
Minor Faults                     35154       36784
Major Faults                       611        1305
Swap Ins                           394        1651
Swap Outs                         4394        5891
Allocation stalls               118616       44781
Direct pages scanned           4935171     4602313
Kswapd pages scanned          15921292    16258483
Kswapd pages reclaimed        15913301    16248305
Direct pages reclaimed         4933368     4601133
Kswapd efficiency                  99%         99%
Kswapd velocity             670088.047  682555.961
Direct efficiency                  99%         99%
Direct velocity             207709.217  193212.133
Percentage direct scans            23%         22%
Page writes by reclaim        4858.000    6232.000
Page writes file                   464         341
Page writes anon                  4394        5891

Note that there are fewer allocation stalls even though the amount
of direct reclaim scanning is very approximately the same.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:12 -07:00
Kirill A. Shutemov 850e9c69ca mm: fix typo in comment in do_fault_around()
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:11 -07:00
Matthew Wilcox 7fc34a62ca mm/msync.c: sync only the requested range in msync()
msync() currently syncs more than POSIX requires or BSD or Solaris
implement.  It is supposed to be equivalent to fdatasync(), not fsync(),
and it is only supposed to sync the portion of the file that overlaps the
range passed to msync.

If the VMA is non-linear, fall back to syncing the entire file, but we
still optimise to only fdatasync() the entire file, not the full fsync().

akpm: there are obvious concerns with bck-compatibility: is anyone relying
on the undocumented side-effect for their data integrity?  And how would
they ever know if this change broke their data integrity?

We think the risk is reasonably low, and this patch brings the kernel into
line with other OS's and with what the manpage has always said...

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Chris Mason <clm@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:11 -07:00
Vlastimil Babka be9765722e mm, compaction: properly signal and act upon lock and need_sched() contention
Compaction uses compact_checklock_irqsave() function to periodically check
for lock contention and need_resched() to either abort async compaction,
or to free the lock, schedule and retake the lock.  When aborting,
cc->contended is set to signal the contended state to the caller.  Two
problems have been identified in this mechanism.

First, compaction also calls directly cond_resched() in both scanners when
no lock is yet taken.  This call either does not abort async compaction,
or set cc->contended appropriately.  This patch introduces a new
compact_should_abort() function to achieve both.  In isolate_freepages(),
the check frequency is reduced to once by SWAP_CLUSTER_MAX pageblocks to
match what the migration scanner does in the preliminary page checks.  In
case a pageblock is found suitable for calling isolate_freepages_block(),
the checks within there are done on higher frequency.

Second, isolate_freepages() does not check if isolate_freepages_block()
aborted due to contention, and advances to the next pageblock.  This
violates the principle of aborting on contention, and might result in
pageblocks not being scanned completely, since the scanning cursor is
advanced.  This problem has been noticed in the code by Joonsoo Kim when
reviewing related patches.  This patch makes isolate_freepages_block()
check the cc->contended flag and abort.

In case isolate_freepages() has already isolated some pages before
aborting due to contention, page migration will proceed, which is OK since
we do not want to waste the work that has been done, and page migration
has own checks for contention.  However, we do not want another isolation
attempt by either of the scanners, so cc->contended flag check is added
also to compaction_alloc() and compact_finished() to make sure compaction
is aborted right after the migration.

The outcome of the patch should be reduced lock contention by async
compaction and lower latencies for higher-order allocations where direct
compaction is involved.

[akpm@linux-foundation.org: fix typo in comment]
Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
Cc: David Rientjes <rientjes@google.com>
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>
2014-06-04 16:54:11 -07:00
Jianyu Zhan 4be89a3460 mm/vmscan.c: use DIV_ROUND_UP for calculation of zone's balance_gap and correct comments.
Currently, we use (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1)
/ KSWAPD_ZONE_BALANCE_GAP_RATIO to avoid a zero gap value.  It's better to
use DIV_ROUND_UP macro for neater code and clear meaning.

Besides, the gap value is calculated against the per-zone "managed pages",
not "present pages".  This patch also corrects the comment and do some
rephrasing.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:11 -07:00
Jianyu Zhan 8f34af6f93 mm, hugetlb: move the error handle logic out of normal code path
alloc_huge_page() now mixes normal code path with error handle logic.
This patches move out the error handle logic, to make normal code path
more clean and redue code duplicate.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Acked-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:10 -07:00
Naoya Horiguchi 6edd6cc662 mm/memory-failure.c: move comment
The comment about pages under writeback is far from the relevant code, so
let's move it to the right place.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:10 -07:00
Mel Gorman 888cf2db47 mm: avoid unnecessary atomic operations during end_page_writeback()
If a page is marked for immediate reclaim then it is moved to the tail of
the LRU list.  This occurs when the system is under enough memory pressure
for pages under writeback to reach the end of the LRU but we test for this
using atomic operations on every writeback.  This patch uses an optimistic
non-atomic test first.  It'll miss some pages in rare cases but the
consequences are not severe enough to warrant such a penalty.

While the function does not dominate profiles during a simple dd test the
cost of it is reduced.

73048     0.7428  vmlinux-3.15.0-rc5-mmotm-20140513 end_page_writeback
23740     0.2409  vmlinux-3.15.0-rc5-lessatomic     end_page_writeback

Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:10 -07:00
Mel Gorman d8846374a8 mm: page_alloc: calculate classzone_idx once from the zonelist ref
There is no need to calculate zone_idx(preferred_zone) multiple times
or use the pgdat to figure it out.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:10 -07:00
Mel Gorman 2457aec637 mm: non-atomically mark page accessed during page cache allocation where possible
aops->write_begin may allocate a new page and make it visible only to have
mark_page_accessed called almost immediately after.  Once the page is
visible the atomic operations are necessary which is noticable overhead
when writing to an in-memory filesystem like tmpfs but should also be
noticable with fast storage.  The objective of the patch is to initialse
the accessed information with non-atomic operations before the page is
visible.

The bulk of filesystems directly or indirectly use
grab_cache_page_write_begin or find_or_create_page for the initial
allocation of a page cache page.  This patch adds an init_page_accessed()
helper which behaves like the first call to mark_page_accessed() but may
called before the page is visible and can be done non-atomically.

The primary APIs of concern in this care are the following and are used
by most filesystems.

	find_get_page
	find_lock_page
	find_or_create_page
	grab_cache_page_nowait
	grab_cache_page_write_begin

All of them are very similar in detail to the patch creates a core helper
pagecache_get_page() which takes a flags parameter that affects its
behavior such as whether the page should be marked accessed or not.  Then
old API is preserved but is basically a thin wrapper around this core
function.

Each of the filesystems are then updated to avoid calling
mark_page_accessed when it is known that the VM interfaces have already
done the job.  There is a slight snag in that the timing of the
mark_page_accessed() has now changed so in rare cases it's possible a page
gets to the end of the LRU as PageReferenced where as previously it might
have been repromoted.  This is expected to be rare but it's worth the
filesystem people thinking about it in case they see a problem with the
timing change.  It is also the case that some filesystems may be marking
pages accessed that previously did not but it makes sense that filesystems
have consistent behaviour in this regard.

The test case used to evaulate this is a simple dd of a large file done
multiple times with the file deleted on each iterations.  The size of the
file is 1/10th physical memory to avoid dirty page balancing.  In the
async case it will be possible that the workload completes without even
hitting the disk and will have variable results but highlight the impact
of mark_page_accessed for async IO.  The sync results are expected to be
more stable.  The exception is tmpfs where the normal case is for the "IO"
to not hit the disk.

The test machine was single socket and UMA to avoid any scheduling or NUMA
artifacts.  Throughput and wall times are presented for sync IO, only wall
times are shown for async as the granularity reported by dd and the
variability is unsuitable for comparison.  As async results were variable
do to writback timings, I'm only reporting the maximum figures.  The sync
results were stable enough to make the mean and stddev uninteresting.

The performance results are reported based on a run with no profiling.
Profile data is based on a separate run with oprofile running.

async dd
                                    3.15.0-rc3            3.15.0-rc3
                                       vanilla           accessed-v2
ext3    Max      elapsed     13.9900 (  0.00%)     11.5900 ( 17.16%)
tmpfs	Max      elapsed      0.5100 (  0.00%)      0.4900 (  3.92%)
btrfs   Max      elapsed     12.8100 (  0.00%)     12.7800 (  0.23%)
ext4	Max      elapsed     18.6000 (  0.00%)     13.3400 ( 28.28%)
xfs	Max      elapsed     12.5600 (  0.00%)      2.0900 ( 83.36%)

The XFS figure is a bit strange as it managed to avoid a worst case by
sheer luck but the average figures looked reasonable.

        samples percentage
ext3       86107    0.9783  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
ext3       23833    0.2710  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
ext3        5036    0.0573  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
ext4       64566    0.8961  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
ext4        5322    0.0713  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
ext4        2869    0.0384  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
xfs        62126    1.7675  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
xfs         1904    0.0554  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
xfs          103    0.0030  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
btrfs      10655    0.1338  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
btrfs       2020    0.0273  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
btrfs        587    0.0079  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
tmpfs      59562    3.2628  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
tmpfs       1210    0.0696  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
tmpfs         94    0.0054  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed

[akpm@linux-foundation.org: don't run init_page_accessed() against an uninitialised pointer]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Tested-by: Prabhakar Lad <prabhakar.csengg@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:10 -07:00
Mel Gorman 6fb81a17d2 mm: do not use unnecessary atomic operations when adding pages to the LRU
When adding pages to the LRU we clear the active bit unconditionally.
As the page could be reachable from other paths we cannot use unlocked
operations without risk of corruption such as a parallel
mark_page_accessed.  This patch tests if is necessary to clear the
active flag before using an atomic operation.  This potentially opens a
tiny race when PageActive is checked as mark_page_accessed could be
called after PageActive was checked.  The race already exists but this
patch changes it slightly.  The consequence is that that the page may be
promoted to the active list that might have been left on the inactive
list before the patch.  It's too tiny a race and too marginal a
consequence to always use atomic operations for.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:10 -07:00
Mel Gorman e3741b506c mm: do not use atomic operations when releasing pages
There should be no references to it any more and a parallel mark should
not be reordered against us.  Use non-locked varient to clear page active.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:09 -07:00
Mel Gorman 07a4278843 mm: shmem: avoid atomic operation during shmem_getpage_gfp
shmem_getpage_gfp uses an atomic operation to set the SwapBacked field
before it's even added to the LRU or visible.  This is unnecessary as what
could it possible race against?  Use an unlocked variant.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:09 -07:00
Mel Gorman b745bc85f2 mm: page_alloc: convert hot/cold parameter and immediate callers to bool
cold is a bool, make it one.  Make the likely case the "if" part of the
block instead of the else as according to the optimisation manual this is
preferred.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:09 -07:00
Mel Gorman 7aeb09f910 mm: page_alloc: use unsigned int for order in more places
X86 prefers the use of unsigned types for iterators and there is a
tendency to mix whether a signed or unsigned type if used for page order.
This converts a number of sites in mm/page_alloc.c to use unsigned int for
order where possible.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:09 -07:00
Mel Gorman cfc47a2803 mm: page_alloc: lookup pageblock migratetype with IRQs enabled during free
get_pageblock_migratetype() is called during free with IRQs disabled.
This is unnecessary and disables IRQs for longer than necessary.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:09 -07:00
Mel Gorman dc4b0caff2 mm: page_alloc: reduce number of times page_to_pfn is called
In the free path we calculate page_to_pfn multiple times. Reduce that.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:09 -07:00
Mel Gorman e58469bafd mm: page_alloc: use word-based accesses for get/set pageblock bitmaps
The test_bit operations in get/set pageblock flags are expensive.  This
patch reads the bitmap on a word basis and use shifts and masks to isolate
the bits of interest.  Similarly masks are used to set a local copy of the
bitmap and then use cmpxchg to update the bitmap if there have been no
other changes made in parallel.

In a test running dd onto tmpfs the overhead of the pageblock-related
functions went from 1.27% in profiles to 0.5%.

In addition to the performance benefits, this patch closes races that are
possible between:

a) get_ and set_pageblock_migratetype(), where get_pageblock_migratetype()
   reads part of the bits before and other part of the bits after
   set_pageblock_migratetype() has updated them.

b) set_pageblock_migratetype() and set_pageblock_skip(), where the non-atomic
   read-modify-update set bit operation in set_pageblock_skip() will cause
   lost updates to some bits changed in the set_pageblock_migratetype().

Joonsoo Kim first reported the case a) via code inspection.  Vlastimil
Babka's testing with a debug patch showed that either a) or b) occurs
roughly once per mmtests' stress-highalloc benchmark (although not
necessarily in the same pageblock).  Furthermore during development of
unrelated compaction patches, it was observed that frequent calls to
{start,undo}_isolate_page_range() the race occurs several thousands of
times and has resulted in NULL pointer dereferences in move_freepages()
and free_one_page() in places where free_list[migratetype] is
manipulated by e.g.  list_move().  Further debugging confirmed that
migratetype had invalid value of 6, causing out of bounds access to the
free_list array.

That confirmed that the race exist, although it may be extremely rare,
and currently only fatal where page isolation is performed due to
memory hot remove.  Races on pageblocks being updated by
set_pageblock_migratetype(), where both old and new migratetype are
lower MIGRATE_RESERVE, currently cannot result in an invalid value
being observed, although theoretically they may still lead to
unexpected creation or destruction of MIGRATE_RESERVE pageblocks.
Furthermore, things could get suddenly worse when memory isolation is
used more, or when new migratetypes are added.

After this patch, the race has no longer been observed in testing.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reported-and-tested-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:09 -07:00
Mel Gorman 5dab29113c mm: page_alloc: take the ALLOC_NO_WATERMARK check out of the fast path
ALLOC_NO_WATERMARK is set in a few cases.  Always by kswapd, always for
__GFP_MEMALLOC, sometimes for swap-over-nfs, tasks etc.  Each of these
cases are relatively rare events but the ALLOC_NO_WATERMARK check is an
unlikely branch in the fast path.  This patch moves the check out of the
fast path and after it has been determined that the watermarks have not
been met.  This helps the common fast path at the cost of making the slow
path slower and hitting kswapd with a performance cost.  It's a reasonable
tradeoff.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:09 -07:00
Mel Gorman a6e21b14f2 mm: page_alloc: only check the alloc flags and gfp_mask for dirty once
Currently it's calculated once per zone in the zonelist.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:09 -07:00
Mel Gorman d34c5fa06f mm: page_alloc: only check the zone id check if pages are buddies
A node/zone index is used to check if pages are compatible for merging
but this happens unconditionally even if the buddy page is not free. Defer
the calculation as long as possible. Ideally we would check the zone boundary
but nodes can overlap.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:08 -07:00
Mel Gorman 664eeddeef mm: page_alloc: use jump labels to avoid checking number_of_cpusets
If cpusets are not in use then we still check a global variable on every
page allocation.  Use jump labels to avoid the overhead.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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>
2014-06-04 16:54:08 -07:00
Mel Gorman 800a1e750c mm: page_alloc: do not treat a zone that cannot be used for dirty pages as "full"
If a zone cannot be used for a dirty page then it gets marked "full" which
is cached in the zlc and later potentially skipped by allocation requests
that have nothing to do with dirty zones.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-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>
2014-06-04 16:54:08 -07:00
Mel Gorman 65bb371984 mm: page_alloc: do not update zlc unless the zlc is active
The zlc is used on NUMA machines to quickly skip over zones that are full.
 However it is always updated, even for the first zone scanned when the
zlc might not even be active.  As it's a write to a bitmap that
potentially bounces cache line it's deceptively expensive and most
machines will not care.  Only update the zlc if it was active.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-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>
2014-06-04 16:54:08 -07:00
Vladimir Davydov 0bd62b1190 slab: delete cache from list after __kmem_cache_shutdown succeeds
Currently, on kmem_cache_destroy we delete the cache from the slab_list
before __kmem_cache_shutdown, inserting it back to the list on failure.
Initially, this was done, because we could release the slab_mutex in
__kmem_cache_shutdown to delete sysfs slub entry, but since commit
41a212859a ("slub: use sysfs'es release mechanism for kmem_cache") we
remove sysfs entry later in kmem_cache_destroy after dropping the
slab_mutex, so that no implementation of __kmem_cache_shutdown can ever
release the lock.  Therefore we can simplify the code a bit by moving
list_del after __kmem_cache_shutdown.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:08 -07:00
Vladimir Davydov 776ed0f037 memcg: cleanup kmem cache creation/destruction functions naming
Current names are rather inconsistent. Let's try to improve them.

Brief change log:

** old name **                          ** new name **

kmem_cache_create_memcg                 memcg_create_kmem_cache
memcg_kmem_create_cache                 memcg_regsiter_cache
memcg_kmem_destroy_cache                memcg_unregister_cache

kmem_cache_destroy_memcg_children       memcg_cleanup_cache_params
mem_cgroup_destroy_all_caches           memcg_unregister_all_caches

create_work                             memcg_register_cache_work
memcg_create_cache_work_func            memcg_register_cache_func
memcg_create_cache_enqueue              memcg_schedule_register_cache

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:08 -07:00
Andy Shevchenko 172cb4b3d4 mm/dmapool.c: reuse devres_release() to free resources
Instead of calling an additional routine in dmam_pool_destroy() rely on
what dmam_pool_release() is doing.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:08 -07:00
Dan Streetman 18ab4d4ced swap: change swap_list_head to plist, add swap_avail_head
Originally get_swap_page() started iterating through the singly-linked
list of swap_info_structs using swap_list.next or highest_priority_index,
which both were intended to point to the highest priority active swap
target that was not full.  The first patch in this series changed the
singly-linked list to a doubly-linked list, and removed the logic to start
at the highest priority non-full entry; it starts scanning at the highest
priority entry each time, even if the entry is full.

Replace the manually ordered swap_list_head with a plist, swap_active_head.
Add a new plist, swap_avail_head.  The original swap_active_head plist
contains all active swap_info_structs, as before, while the new
swap_avail_head plist contains only swap_info_structs that are active and
available, i.e. not full.  Add a new spinlock, swap_avail_lock, to protect
the swap_avail_head list.

Mel Gorman suggested using plists since they internally handle ordering
the list entries based on priority, which is exactly what swap was doing
manually.  All the ordering code is now removed, and swap_info_struct
entries and simply added to their corresponding plist and automatically
ordered correctly.

Using a new plist for available swap_info_structs simplifies and
optimizes get_swap_page(), which no longer has to iterate over full
swap_info_structs.  Using a new spinlock for swap_avail_head plist
allows each swap_info_struct to add or remove themselves from the
plist when they become full or not-full; previously they could not
do so because the swap_info_struct->lock is held when they change
from full<->not-full, and the swap_lock protecting the main
swap_active_head must be ordered before any swap_info_struct->lock.

Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shli@fusionio.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Cc: Weijie Yang <weijieut@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:07 -07:00
Dan Streetman adfab836f4 swap: change swap_info singly-linked list to list_head
The logic controlling the singly-linked list of swap_info_struct entries
for all active, i.e.  swapon'ed, swap targets is rather complex, because:

 - it stores the entries in priority order
 - there is a pointer to the highest priority entry
 - there is a pointer to the highest priority not-full entry
 - there is a highest_priority_index variable set outside the swap_lock
 - swap entries of equal priority should be used equally

this complexity leads to bugs such as: https://lkml.org/lkml/2014/2/13/181
where different priority swap targets are incorrectly used equally.

That bug probably could be solved with the existing singly-linked lists,
but I think it would only add more complexity to the already difficult to
understand get_swap_page() swap_list iteration logic.

The first patch changes from a singly-linked list to a doubly-linked list
using list_heads; the highest_priority_index and related code are removed
and get_swap_page() starts each iteration at the highest priority
swap_info entry, even if it's full.  While this does introduce unnecessary
list iteration (i.e.  Schlemiel the painter's algorithm) in the case where
one or more of the highest priority entries are full, the iteration and
manipulation code is much simpler and behaves correctly re: the above bug;
and the fourth patch removes the unnecessary iteration.

The second patch adds some minor plist helper functions; nothing new
really, just functions to match existing regular list functions.  These
are used by the next two patches.

The third patch adds plist_requeue(), which is used by get_swap_page() in
the next patch - it performs the requeueing of same-priority entries
(which moves the entry to the end of its priority in the plist), so that
all equal-priority swap_info_structs get used equally.

The fourth patch converts the main list into a plist, and adds a new plist
that contains only swap_info entries that are both active and not full.
As Mel suggested using plists allows removing all the ordering code from
swap - plists handle ordering automatically.  The list naming is also
clarified now that there are two lists, with the original list changed
from swap_list_head to swap_active_head and the new list named
swap_avail_head.  A new spinlock is also added for the new list, so
swap_info entries can be added or removed from the new list immediately as
they become full or not full.

This patch (of 4):

Replace the singly-linked list tracking active, i.e.  swapon'ed,
swap_info_struct entries with a doubly-linked list using struct
list_heads.  Simplify the logic iterating and manipulating the list of
entries, especially get_swap_page(), by using standard list_head
functions, and removing the highest priority iteration logic.

The change fixes the bug:
https://lkml.org/lkml/2014/2/13/181
in which different priority swap entries after the highest priority entry
are incorrectly used equally in pairs.  The swap behavior is now as
advertised, i.e. different priority swap entries are used in order, and
equal priority swap targets are used concurrently.

Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shli@fusionio.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Cc: Weijie Yang <weijieut@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:07 -07:00
Jianyu Zhan 7ee07a44eb mm: fold mlocked_vma_newpage() into its only call site
In previous commit(mm: use the light version __mod_zone_page_state in
mlocked_vma_newpage()) a irq-unsafe __mod_zone_page_state is used.  And as
suggested by Andrew, to reduce the risks that new call sites incorrectly
using mlocked_vma_newpage() without knowing they are adding racing, this
patch folds mlocked_vma_newpage() into its only call site,
page_add_new_anon_rmap, to make it open-cocded for people to know what is
going on.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Hugh Dickins <hughd@google.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>
2014-06-04 16:54:07 -07:00
Jianyu Zhan bea04b0732 mm: use the light version __mod_zone_page_state in mlocked_vma_newpage()
mlocked_vma_newpage() is called with pte lock held(a spinlock), which
implies preemtion disabled, and the vm stat counter is not modified from
interrupt context, so we need not use an irq-safe mod_zone_page_state()
here, using a light-weight version __mod_zone_page_state() would be OK.

This patch also documents __mod_zone_page_state() and some of its
callsites.  The comment above __mod_zone_page_state() is from Hugh
Dickins, and acked by Christoph.

Most credits to Hugh and Christoph for the clarification on the usage of
the __mod_zone_page_state().

[akpm@linux-foundation.org: coding-style fixes]
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:07 -07:00
Vlastimil Babka e9ade56991 mm/compaction: avoid rescanning pageblocks in isolate_freepages
The compaction free scanner in isolate_freepages() currently remembers PFN
of the highest pageblock where it successfully isolates, to be used as the
starting pageblock for the next invocation.  The rationale behind this is
that page migration might return free pages to the allocator when
migration fails and we don't want to skip them if the compaction
continues.

Since migration now returns free pages back to compaction code where they
can be reused, this is no longer a concern.  This patch changes
isolate_freepages() so that the PFN for restarting is updated with each
pageblock where isolation is attempted.  Using stress-highalloc from
mmtests, this resulted in 10% reduction of the pages scanned by the free
scanner.

Note that the somewhat similar functionality that records highest
successful pageblock in zone->compact_cached_free_pfn, remains unchanged.
This cache is used when the whole compaction is restarted, not for
multiple invocations of the free scanner during single compaction.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:07 -07:00
Vlastimil Babka f8c9301fa5 mm/compaction: do not count migratepages when unnecessary
During compaction, update_nr_listpages() has been used to count remaining
non-migrated and free pages after a call to migrage_pages().  The
freepages counting has become unneccessary, and it turns out that
migratepages counting is also unnecessary in most cases.

The only situation when it's needed to count cc->migratepages is when
migrate_pages() returns with a negative error code.  Otherwise, the
non-negative return value is the number of pages that were not migrated,
which is exactly the count of remaining pages in the cc->migratepages
list.

Furthermore, any non-zero count is only interesting for the tracepoint of
mm_compaction_migratepages events, because after that all remaining
unmigrated pages are put back and their count is set to 0.

This patch therefore removes update_nr_listpages() completely, and changes
the tracepoint definition so that the manual counting is done only when
the tracepoint is enabled, and only when migrate_pages() returns a
negative error code.

Furthermore, migrate_pages() and the tracepoints won't be called when
there's nothing to migrate.  This potentially avoids some wasted cycles
and reduces the volume of uninteresting mm_compaction_migratepages events
where "nr_migrated=0 nr_failed=0".  In the stress-highalloc mmtest, this
was about 75% of the events.  The mm_compaction_isolate_migratepages event
is better for determining that nothing was isolated for migration, and
this one was just duplicating the info.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:07 -07:00
David Rientjes aeef4b8380 mm, compaction: terminate async compaction when rescheduling
Async compaction terminates prematurely when need_resched(), see
compact_checklock_irqsave().  This can never trigger, however, if the
cond_resched() in isolate_migratepages_range() always takes care of the
scheduling.

If the cond_resched() actually triggers, then terminate this pageblock
scan for async compaction as well.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:07 -07:00
David Rientjes 75f30861a1 mm, thp: avoid excessive compaction latency during fault
Synchronous memory compaction can be very expensive: it can iterate an
enormous amount of memory without aborting, constantly rescheduling,
waiting on page locks and lru_lock, etc, if a pageblock cannot be
defragmented.

Unfortunately, it's too expensive for transparent hugepage page faults and
it's much better to simply fallback to pages.  On 128GB machines, we find
that synchronous memory compaction can take O(seconds) for a single thp
fault.

Now that async compaction remembers where it left off without strictly
relying on sync compaction, this makes thp allocations best-effort without
causing egregious latency during fault.  We still need to retry async
compaction after reclaim, but this won't stall for seconds.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Greg Thelen <gthelen@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:06 -07:00
David Rientjes e0b9daeb45 mm, compaction: embed migration mode in compact_control
We're going to want to manipulate the migration mode for compaction in the
page allocator, and currently compact_control's sync field is only a bool.

Currently, we only do MIGRATE_ASYNC or MIGRATE_SYNC_LIGHT compaction
depending on the value of this bool.  Convert the bool to enum
migrate_mode and pass the migration mode in directly.  Later, we'll want
to avoid MIGRATE_SYNC_LIGHT for thp allocations in the pagefault patch to
avoid unnecessary latency.

This also alters compaction triggered from sysfs, either for the entire
system or for a node, to force MIGRATE_SYNC.

[akpm@linux-foundation.org: fix build]
[iamjoonsoo.kim@lge.com: use MIGRATE_SYNC in alloc_contig_range()]
Signed-off-by: David Rientjes <rientjes@google.com>
Suggested-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:06 -07:00
David Rientjes 35979ef339 mm, compaction: add per-zone migration pfn cache for async compaction
Each zone has a cached migration scanner pfn for memory compaction so that
subsequent calls to memory compaction can start where the previous call
left off.

Currently, the compaction migration scanner only updates the per-zone
cached pfn when pageblocks were not skipped for async compaction.  This
creates a dependency on calling sync compaction to avoid having subsequent
calls to async compaction from scanning an enormous amount of non-MOVABLE
pageblocks each time it is called.  On large machines, this could be
potentially very expensive.

This patch adds a per-zone cached migration scanner pfn only for async
compaction.  It is updated everytime a pageblock has been scanned in its
entirety and when no pages from it were successfully isolated.  The cached
migration scanner pfn for sync compaction is updated only when called for
sync compaction.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:06 -07:00
David Rientjes d53aea3d46 mm, compaction: return failed migration target pages back to freelist
Greg reported that he found isolated free pages were returned back to the
VM rather than the compaction freelist.  This will cause holes behind the
free scanner and cause it to reallocate additional memory if necessary
later.

He detected the problem at runtime seeing that ext4 metadata pages (esp
the ones read by "sbi->s_group_desc[i] = sb_bread(sb, block)") were
constantly visited by compaction calls of migrate_pages().  These pages
had a non-zero b_count which caused fallback_migrate_page() ->
try_to_release_page() -> try_to_free_buffers() to fail.

Memory compaction works by having a "freeing scanner" scan from one end of
a zone which isolates pages as migration targets while another "migrating
scanner" scans from the other end of the same zone which isolates pages
for migration.

When page migration fails for an isolated page, the target page is
returned to the system rather than the freelist built by the freeing
scanner.  This may require the freeing scanner to continue scanning memory
after suitable migration targets have already been returned to the system
needlessly.

This patch returns destination pages to the freeing scanner freelist when
page migration fails.  This prevents unnecessary work done by the freeing
scanner but also encourages memory to be as compacted as possible at the
end of the zone.

Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Greg Thelen <gthelen@google.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:06 -07:00
David Rientjes 68711a7463 mm, migration: add destination page freeing callback
Memory migration uses a callback defined by the caller to determine how to
allocate destination pages.  When migration fails for a source page,
however, it frees the destination page back to the system.

This patch adds a memory migration callback defined by the caller to
determine how to free destination pages.  If a caller, such as memory
compaction, builds its own freelist for migration targets, this can reuse
already freed memory instead of scanning additional memory.

If the caller provides a function to handle freeing of destination pages,
it is called when page migration fails.  If the caller passes NULL then
freeing back to the system will be handled as usual.  This patch
introduces no functional change.

Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:06 -07:00
Vladimir Davydov 93f39eea9c memcg: memcg_kmem_create_cache: make memcg_name_buf statically allocated
It isn't worth complicating the code by allocating it on the first access,
because it only takes 256 bytes.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:06 -07:00
Vladimir Davydov 073ee1c6cd memcg: get rid of memcg_create_cache_name
Instead of calling back to memcontrol.c from kmem_cache_create_memcg in
order to just create the name of a per memcg cache, let's allocate it in
place.  We only need to pass the memcg name to kmem_cache_create_memcg for
that - everything else can be done in slab_common.c.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:06 -07:00
Qiang Huang b5ffc8560c memcg: correct comments for __mem_cgroup_begin_update_page_stat
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:06 -07:00
Qiang Huang bdcbb659fe memcg: fold mem_cgroup_stolen
It is only used in __mem_cgroup_begin_update_page_stat(), the name is
confusing and 2 routines for one thing also confuse people, so fold this
function seems more clear.

[akpm@linux-foundation.org: fix typo, per Michal]
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:05 -07:00
Fabian Frederick b46e14acb8 mm/mempolicy.c: parameter doc uniformization
Also fixes kernel-doc warning

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:05 -07:00
Kirill A. Shutemov ac7695012a mm/rmap.c: make page_referenced_one() and try_to_unmap_one() static
KSM was converted to use rmap_walk() and now nobody uses these functions
outside mm/rmap.c.

Let's covert them back to static.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:05 -07:00
Kirill A. Shutemov fa5bb2093a mm: cleanup __get_user_pages()
Get rid of two nested loops over nr_pages, extract vma flags checking to
separate function and other random cleanups.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:05 -07:00
Kirill A. Shutemov 1674448345 mm: extract code to fault in a page from __get_user_pages()
Nesting level in __get_user_pages() is just insane. Let's try to fix it
a bit.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:05 -07:00
Kirill A. Shutemov 69e68b4f03 mm: cleanup follow_page_mask()
Cleanups:
 - move pte-related code to separate function. It's about half of the
   function;
 - get rid of some goto-logic;
 - use 'return NULL' instead of 'return page' where page can only be
   NULL;

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:04 -07:00
Kirill A. Shutemov f2b495ca82 mm: extract in_gate_area() case from __get_user_pages()
The case is special and disturb from reading main __get_user_pages()
code path. Let's move it to separate function.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:04 -07:00
Kirill A. Shutemov 4bbd4c776a mm: move get_user_pages()-related code to separate file
mm/memory.c is overloaded: over 4k lines. get_user_pages() code is
pretty much self-contained let's move it to separate file.

No other changes made.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:04 -07:00
Fabian Frederick f4527c9086 mm/vmalloc.c: replace seq_printf by seq_puts
Replace seq_printf where possible

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:04 -07:00
Fabian Frederick ada4ba5914 mm/memcontrol.c: remove NULL assignment on static
static values are automatically initialized to NULL

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:04 -07:00
Dave Hansen df9024a8c5 mm: shrinker: add nid to tracepoint output
Now that we are doing NUMA-aware shrinking, and can have shrinkers
running in parallel, or working on individual nodes, it seems like we
should also be sticking the node in the output.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Chinner <david@fromorbit.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:04 -07:00
Dave Hansen 7fe7047597 mm: shrinker trace points: fix negatives
I was looking at a trace of the slab shrinkers (attachment in this comment):

	https://bugs.freedesktop.org/show_bug.cgi?id=72742#c67

and noticed that "total_scan" can go negative in some cases.  We
used to dump out the "total_scan" variable directly, but some of
the shrinker modifications along the way changed that.

This patch just dumps it out directly, again.  It doesn't make
any sense to derive it from new_nr and nr any more since there
are now other shrinkers that can be running in parallel and
mucking with those values.

Here's an example of the negative numbers in the output:

>          kswapd0-840   [000]   160.869398: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 10 new scan count 39 total_scan 29 last shrinker return val 256
>          kswapd0-840   [000]   160.869618: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 39 new scan count 102 total_scan 63 last shrinker return val 256
>          kswapd0-840   [000]   160.870031: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 102 new scan count 47 total_scan -55 last shrinker return val 768
>          kswapd0-840   [000]   160.870464: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 47 new scan count 45 total_scan -2 last shrinker return val 768
>          kswapd0-840   [000]   163.384144: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 45 new scan count 56 total_scan 11 last shrinker return val 0
>          kswapd0-840   [000]   163.384297: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 56 new scan count 15 total_scan -41 last shrinker return val 256
>          kswapd0-840   [000]   163.384414: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 15 new scan count 117 total_scan 102 last shrinker return val 0
>          kswapd0-840   [000]   163.384657: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 117 new scan count 36 total_scan -81 last shrinker return val 512
>          kswapd0-840   [000]   163.384880: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 36 new scan count 111 total_scan 75 last shrinker return val 256
>          kswapd0-840   [000]   163.385256: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 111 new scan count 34 total_scan -77 last shrinker return val 768
>          kswapd0-840   [000]   163.385598: mm_shrink_slab_end:   i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 34 new scan count 122 total_scan 88 last shrinker return val 512

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Chinner <david@fromorbit.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:04 -07:00
Daeseok Youn cc6b664aa2 mm/dmapool.c: remove redundant NULL check for dev in dma_pool_create()
"dev" cannot be NULL because it is already checked before calling
dma_pool_create().

If dev ever was NULL, the code would oops in dev_to_node() after enabling
CONFIG_NUMA.

It is possible that some driver is using dev==NULL and has never been run
on a NUMA machine.  Such a driver is probably outdated, possibly buggy and
will need some attention if it starts triggering NULL derefs.

Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:04 -07:00
Jianyu Zhan d2ee40eae9 mm: introdule compound_head_by_tail()
Currently, in put_compound_page(), we have

======
if (likely(!PageTail(page))) {                  <------  (1)
        if (put_page_testzero(page)) {
                 /*
                 ¦* By the time all refcounts have been released
                 ¦* split_huge_page cannot run anymore from under us.
                 ¦*/
                 if (PageHead(page))
                         __put_compound_page(page);
                 else
                         __put_single_page(page);
         }
         return;
}

/* __split_huge_page_refcount can run under us */
page_head = compound_head(page);        <------------ (2)
======

if at (1) ,  we fail the check, this means page is *likely* a tail page.

Then at (2), as compoud_head(page) is inlined, it is :

======
static inline struct page *compound_head(struct page *page)
{
          if (unlikely(PageTail(page))) {           <----------- (3)
              struct page *head = page->first_page;

                smp_rmb();
                if (likely(PageTail(page)))
                        return head;
        }
        return page;
}
======

here, the (3) unlikely in the case is a negative hint, because it is
*likely* a tail page.  So the check (3) in this case is not good, so I
introduce a helper for this case.

So this patch introduces compound_head_by_tail() which deals with a
possible tail page(though it could be spilt by a racy thread), and make
compound_head() a wrapper on it.

This patch has no functional change, and it reduces the object
size slightly:
   text    data     bss     dec     hex  filename
  11003    1328      16   12347    303b  mm/swap.o.orig
  10971    1328      16   12315    301b  mm/swap.o.patched

I've ran "perf top -e branch-miss" to observe branch-miss in this case.
As Michael points out, it's a slow path, so only very few times this case
happens.  But I grep'ed the code base, and found there still are some
other call sites could be benifited from this helper.  And given that it
only bloating up the source by only 5 lines, but with a reduced object
size.  I still believe this helper deserves to exsit.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.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>
2014-06-04 16:54:03 -07:00
Jianyu Zhan 4bd3e8f7b9 mm/swap.c: split put_compound_page()
Currently, put_compound_page() carefully handles tricky cases to avoid
racing with compound page releasing or splitting, which makes it quite
lenthy (about 200+ lines) and needs deep tab indention, which makes it
quite hard to follow and maintain.

Now based on two helpers introduced in the previous patch ("mm/swap.c:
introduce put_[un]refcounted_compound_page helpers for spliting
put_compound_page"), this patch replaces those two lengthy code paths with
these two helpers, respectively.  Also, it has some comment rephrasing.

After this patch, the put_compound_page() is very compact, thus easy to
read and maintain.

After splitting, the object file is of same size as the original one.
Actually, I've diff'ed put_compound_page()'s orginal disassemble code and
the patched disassemble code, the are 100% the same!

This fact shows that this splitting has no functional change, but it
brings readability.

This patch and the previous one blow the code by 32 lines, mostly due to
comments.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.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>
2014-06-04 16:54:03 -07:00
Jianyu Zhan c747ce7907 mm/swap.c: introduce put_[un]refcounted_compound_page helpers for splitting put_compound_page()
Currently, put_compound_page() carefully handles tricky cases to avoid
racing with compound page releasing or splitting, which makes it quite
lenthy (about 200+ lines) and needs deep tab indention, which makes it
quite hard to follow and maintain.

This patch and the next patch refactor this function.

Based on the code skeleton of put_compound_page:

put_compound_pge:
        if !PageTail(page)
        	put head page fastpath;
		return;

        /* else PageTail */
        page_head = compound_head(page)
        if !__compound_tail_refcounted(page_head)
		put head page optimal path; <---(1)
		return;
        else
		put head page slowpath; <--- (2)
                return;

This patch introduces two helpers, put_[un]refcounted_compound_page,
handling the code path (1) and code path (2), respectively.  They both are
tagged __always_inline, thus elmiating function call overhead, making them
operating the same way as before.

They are almost copied verbatim(except one place, a "goto out_put_single"
is expanded), with some comments rephrasing.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.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>
2014-06-04 16:54:03 -07:00
Rasmus Villemoes 23c8902d40 mm: constify nmask argument to set_mempolicy()
The nmask argument to set_mempolicy() is const according to the user-space
header numaif.h, and since the kernel does indeed not modify it, it might
as well be declared const in the kernel.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:03 -07:00
Rasmus Villemoes f7f28ca98b mm: constify nmask argument to mbind()
The nmask argument to mbind() is const according to the userspace header
numaif.h, and since the kernel does indeed not modify it, it might as well
be declared const in the kernel.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
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>
2014-06-04 16:54:03 -07:00
Christoph Lameter 7c8e0181e6 mm: replace __get_cpu_var uses with this_cpu_ptr
Replace places where __get_cpu_var() is used for an address calculation
with this_cpu_ptr().

Signed-off-by: Christoph Lameter <cl@linux.com>
Cc: Tejun Heo <tj@kernel.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>
2014-06-04 16:54:03 -07:00
Fabian Frederick f7e2f7e896 mm/memblock.c: use PFN_DOWN
Replace ((x) >> PAGE_SHIFT) with the pfn macro.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:02 -07:00
Fabian Frederick c8e861a531 mm/memory_hotplug.c: use PFN_DOWN()
Replace ((x) >> PAGE_SHIFT) with the pfn macro.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:02 -07:00
Matthew Wilcox dd6bd0d9c7 swap: use bdev_read_page() / bdev_write_page()
By calling the device driver to write the page directly, we avoid
allocating a BIO, which allows us to free memory without allocating
memory.

[akpm@linux-foundation.org: fix used-uninitialized bug]
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dheeraj Reddy <dheeraj.reddy@intel.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>
2014-06-04 16:54:02 -07:00
Matthew Wilcox 57d998456a fs/mpage.c: factor page_endio() out of mpage_end_io()
page_endio() takes care of updating all the appropriate page flags once
I/O has finished to a page.  Switch to using mapping_set_error() instead
of setting AS_EIO directly; this will handle thin-provisioned devices
correctly.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dheeraj Reddy <dheeraj.reddy@intel.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>
2014-06-04 16:54:02 -07:00
NeilBrown 399ba0b956 mm/vmscan.c: avoid throttling reclaim for loop-back nfsd threads
When a loopback NFS mount is active and the backing device for the NFS
mount becomes congested, that can impose throttling delays on the nfsd
threads.

These delays significantly reduce throughput and so the NFS mount remains
congested.

This results in a livelock and the reduced throughput persists.

This livelock has been found in testing with the 'wait_iff_congested'
call, and could possibly be caused by the 'congestion_wait' call.

This livelock is similar to the deadlock which justified the introduction
of PF_LESS_THROTTLE, and the same flag can be used to remove this
livelock.

To minimise the impact of the change, we still throttle nfsd when the
filesystem it is writing to is congested, but not when some separate
filesystem (e.g.  the NFS filesystem) is congested.

Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:01 -07:00
Mel Gorman 11de9927f9 mm: numa: add migrated transhuge pages to LRU the same way as base pages
Migration of misplaced transhuge pages uses page_add_new_anon_rmap() when
putting the page back as it avoided an atomic operations and added the new
page to the correct LRU.  A side-effect is that the page gets marked
activated as part of the migration meaning that transhuge and base pages
are treated differently from an aging perspective than base page
migration.

This patch uses page_add_anon_rmap() and putback_lru_page() on completion
of a transhuge migration similar to base page migration.  It would require
fewer atomic operations to use lru_cache_add without taking an additional
reference to the page.  The downside would be that it's still different to
base page migration and unevictable pages may be added to the wrong LRU
for cleaning up later.  Testing of the usual workloads did not show any
adverse impact to the change.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.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>
2014-06-04 16:54:01 -07:00
Vladimir Davydov bd67314586 memcg, slab: simplify synchronization scheme
At present, we have the following mutexes protecting data related to per
memcg kmem caches:

 - slab_mutex.  This one is held during the whole kmem cache creation
   and destruction paths.  We also take it when updating per root cache
   memcg_caches arrays (see memcg_update_all_caches).  As a result, taking
   it guarantees there will be no changes to any kmem cache (including per
   memcg).  Why do we need something else then?  The point is it is
   private to slab implementation and has some internal dependencies with
   other mutexes (get_online_cpus).  So we just don't want to rely upon it
   and prefer to introduce additional mutexes instead.

 - activate_kmem_mutex.  Initially it was added to synchronize
   initializing kmem limit (memcg_activate_kmem).  However, since we can
   grow per root cache memcg_caches arrays only on kmem limit
   initialization (see memcg_update_all_caches), we also employ it to
   protect against memcg_caches arrays relocation (e.g.  see
   __kmem_cache_destroy_memcg_children).

 - We have a convention not to take slab_mutex in memcontrol.c, but we
   want to walk over per memcg memcg_slab_caches lists there (e.g.  for
   destroying all memcg caches on offline).  So we have per memcg
   slab_caches_mutex's protecting those lists.

The mutexes are taken in the following order:

   activate_kmem_mutex -> slab_mutex -> memcg::slab_caches_mutex

Such a syncrhonization scheme has a number of flaws, for instance:

 - We can't call kmem_cache_{destroy,shrink} while walking over a
   memcg::memcg_slab_caches list due to locking order.  As a result, in
   mem_cgroup_destroy_all_caches we schedule the
   memcg_cache_params::destroy work shrinking and destroying the cache.

 - We don't have a mutex to synchronize per memcg caches destruction
   between memcg offline (mem_cgroup_destroy_all_caches) and root cache
   destruction (__kmem_cache_destroy_memcg_children).  Currently we just
   don't bother about it.

This patch simplifies it by substituting per memcg slab_caches_mutex's
with the global memcg_slab_mutex.  It will be held whenever a new per
memcg cache is created or destroyed, so it protects per root cache
memcg_caches arrays and per memcg memcg_slab_caches lists.  The locking
order is following:

   activate_kmem_mutex -> memcg_slab_mutex -> slab_mutex

This allows us to call kmem_cache_{create,shrink,destroy} under the
memcg_slab_mutex.  As a result, we don't need memcg_cache_params::destroy
work any more - we can simply destroy caches while iterating over a per
memcg slab caches list.

Also using the global mutex simplifies synchronization between concurrent
per memcg caches creation/destruction, e.g.  mem_cgroup_destroy_all_caches
vs __kmem_cache_destroy_memcg_children.

The downside of this is that we substitute per-memcg slab_caches_mutex's
with a hummer-like global mutex, but since we already take either the
slab_mutex or the cgroup_mutex along with a memcg::slab_caches_mutex, it
shouldn't hurt concurrency a lot.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:01 -07:00
Vladimir Davydov c67a8a685a memcg, slab: merge memcg_{bind,release}_pages to memcg_{un}charge_slab
Currently we have two pairs of kmemcg-related functions that are called on
slab alloc/free.  The first is memcg_{bind,release}_pages that count the
total number of pages allocated on a kmem cache.  The second is
memcg_{un}charge_slab that {un}charge slab pages to kmemcg resource
counter.  Let's just merge them to keep the code clean.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:01 -07:00
Vladimir Davydov 1e32e77f95 memcg, slab: do not schedule cache destruction when last page goes away
This patchset is a part of preparations for kmemcg re-parenting.  It
targets at simplifying kmemcg work-flows and synchronization.

First, it removes async per memcg cache destruction (see patches 1, 2).
Now caches are only destroyed on memcg offline.  That means the caches
that are not empty on memcg offline will be leaked.  However, they are
already leaked, because memcg_cache_params::nr_pages normally never drops
to 0 so the destruction work is never scheduled except kmem_cache_shrink
is called explicitly.  In the future I'm planning reaping such dead caches
on vmpressure or periodically.

Second, it substitutes per memcg slab_caches_mutex's with the global
memcg_slab_mutex, which should be taken during the whole per memcg cache
creation/destruction path before the slab_mutex (see patch 3).  This
greatly simplifies synchronization among various per memcg cache
creation/destruction paths.

I'm still not quite sure about the end picture, in particular I don't know
whether we should reap dead memcgs' kmem caches periodically or try to
merge them with their parents (see https://lkml.org/lkml/2014/4/20/38 for
more details), but whichever way we choose, this set looks like a
reasonable change to me, because it greatly simplifies kmemcg work-flows
and eases further development.

This patch (of 3):

After a memcg is offlined, we mark its kmem caches that cannot be deleted
right now due to pending objects as dead by setting the
memcg_cache_params::dead flag, so that memcg_release_pages will schedule
cache destruction (memcg_cache_params::destroy) as soon as the last slab
of the cache is freed (memcg_cache_params::nr_pages drops to zero).

I guess the idea was to destroy the caches as soon as possible, i.e.
immediately after freeing the last object.  However, it just doesn't work
that way, because kmem caches always preserve some pages for the sake of
performance, so that nr_pages never gets to zero unless the cache is
shrunk explicitly using kmem_cache_shrink.  Of course, we could account
the total number of objects on the cache or check if all the slabs
allocated for the cache are empty on kmem_cache_free and schedule
destruction if so, but that would be too costly.

Thus we have a piece of code that works only when we explicitly call
kmem_cache_shrink, but complicates the whole picture a lot.  Moreover,
it's racy in fact.  For instance, kmem_cache_shrink may free the last slab
and thus schedule cache destruction before it finishes checking that the
cache is empty, which can lead to use-after-free.

So I propose to remove this async cache destruction from
memcg_release_pages, and check if the cache is empty explicitly after
calling kmem_cache_shrink instead.  This will simplify things a lot w/o
introducing any functional changes.

And regarding dead memcg caches (i.e.  those that are left hanging around
after memcg offline for they have objects), I suppose we should reap them
either periodically or on vmpressure as Glauber suggested initially.  I'm
going to implement this later.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:01 -07:00
Michal Hocko d8dc595ce3 memcg: do not hang on OOM when killed by userspace OOM access to memory reserves
Eric has reported that he can see task(s) stuck in memcg OOM handler
regularly.  The only way out is to

	echo 0 > $GROUP/memory.oom_control

His usecase is:

- Setup a hierarchy with memory and the freezer (disable kernel oom and
  have a process watch for oom).

- In that memory cgroup add a process with one thread per cpu.

- In one thread slowly allocate once per second I think it is 16M of ram
  and mlock and dirty it (just to force the pages into ram and stay
  there).

- When oom is achieved loop:
  * attempt to freeze all of the tasks.
  * if frozen send every task SIGKILL, unfreeze, remove the directory in
    cgroupfs.

Eric has then pinpointed the issue to be memcg specific.

All tasks are sitting on the memcg_oom_waitq when memcg oom is disabled.
Those that have received fatal signal will bypass the charge and should
continue on their way out.  The tricky part is that the exit path might
trigger a page fault (e.g.  exit_robust_list), thus the memcg charge,
while its memcg is still under OOM because nobody has released any charges
yet.

Unlike with the in-kernel OOM handler the exiting task doesn't get
TIF_MEMDIE set so it doesn't shortcut further charges of the killed task
and falls to the memcg OOM again without any way out of it as there are no
fatal signals pending anymore.

This patch fixes the issue by checking PF_EXITING early in
mem_cgroup_try_charge and bypass the charge same as if it had fatal
signal pending or TIF_MEMDIE set.

Normally exiting tasks (aka not killed) will bypass the charge now but
this should be OK as the task is leaving and will release memory and
increasing the memory pressure just to release it in a moment seems
dubious wasting of cycles.  Besides that charges after exit_signals should
be rare.

I am bringing this patch again (rebased on the current mmotm tree). I
hope we can move forward finally. If there is still an opposition then
I would really appreciate a concurrent approach so that we can discuss
alternatives.

http://comments.gmane.org/gmane.linux.kernel.stable/77650 is a reference
to the followup discussion when the patch has been dropped from the mmotm
last time.

Reported-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:01 -07:00
Mel Gorman 675becce15 mm: vmscan: do not throttle based on pfmemalloc reserves if node has no ZONE_NORMAL
throttle_direct_reclaim() is meant to trigger during swap-over-network
during which the min watermark is treated as a pfmemalloc reserve.  It
throttes on the first node in the zonelist but this is flawed.

The user-visible impact is that a process running on CPU whose local
memory node has no ZONE_NORMAL will stall for prolonged periods of time,
possibly indefintely.  This is due to throttle_direct_reclaim thinking the
pfmemalloc reserves are depleted when in fact they don't exist on that
node.

On a NUMA machine running a 32-bit kernel (I know) allocation requests
from CPUs on node 1 would detect no pfmemalloc reserves and the process
gets throttled.  This patch adjusts throttling of direct reclaim to
throttle based on the first node in the zonelist that has a usable
ZONE_NORMAL or lower zone.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:01 -07:00
Huang Shijie 64ac4940d5 mm/mmap.c: remove the first mapping check
Remove the first mapping check for vma_link.  Move the mutex_lock into the
braces when vma->vm_file is true.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:01 -07:00
Jianyu Zhan 2329d3751b mm/swap.c: clean up *lru_cache_add* functions
In mm/swap.c, __lru_cache_add() is exported, but actually there are no
users outside this file.

This patch unexports __lru_cache_add(), and makes it static.  It also
exports lru_cache_add_file(), as it is use by cifs and fuse, which can
loaded as modules.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shaohua Li <shli@kernel.org>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:00 -07:00
Dave Hansen 613813e898 mm: debug: make bad_range() output more usable and readable
Nobody outputs memory addresses in decimal.  PFNs are essentially
addresses, and they're gibberish in decimal.  Output them in hex.

Also, add the nid and zone name to give a little more context to the
message.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:00 -07:00
Vlastimil Babka c96b9e508f mm/compaction: cleanup isolate_freepages()
isolate_freepages() is currently somewhat hard to follow thanks to many
looks like it is related to the 'low_pfn' variable, but in fact it is not.

This patch renames the 'high_pfn' variable to a hopefully less confusing name,
and slightly changes its handling without a functional change. A comment made
obsolete by recent changes is also updated.

[akpm@linux-foundation.org: comment fixes, per Minchan]
[iamjoonsoo.kim@lge.com: cleanups]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Dongjun Shin <d.j.shin@samsung.com>
Cc: Sunghwan Yun <sunghwan.yun@samsung.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:00 -07:00
Heesub Shin 13fb44e4b0 mm/compaction: clean up unused code lines
Remove code lines currently not in use or never called.

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dongjun Shin <d.j.shin@samsung.com>
Cc: Sunghwan Yun <sunghwan.yun@samsung.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Dongjun Shin <d.j.shin@samsung.com>
Cc: Sunghwan Yun <sunghwan.yun@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:00 -07:00
Vlastimil Babka 5bcc9f86ef mm/page_alloc: prevent MIGRATE_RESERVE pages from being misplaced
For the MIGRATE_RESERVE pages, it is useful when they do not get
misplaced on free_list of other migratetype, otherwise they might get
allocated prematurely and e.g.  fragment the MIGRATE_RESEVE pageblocks.
While this cannot be avoided completely when allocating new
MIGRATE_RESERVE pageblocks in min_free_kbytes sysctl handler, we should
prevent the misplacement where possible.

Currently, it is possible for the misplacement to happen when a
MIGRATE_RESERVE page is allocated on pcplist through rmqueue_bulk() as a
fallback for other desired migratetype, and then later freed back
through free_pcppages_bulk() without being actually used.  This happens
because free_pcppages_bulk() uses get_freepage_migratetype() to choose
the free_list, and rmqueue_bulk() calls set_freepage_migratetype() with
the *desired* migratetype and not the page's original MIGRATE_RESERVE
migratetype.

This patch fixes the problem by moving the call to
set_freepage_migratetype() from rmqueue_bulk() down to
__rmqueue_smallest() and __rmqueue_fallback() where the actual page's
migratetype (e.g.  from which free_list the page is taken from) is used.
Note that this migratetype might be different from the pageblock's
migratetype due to freepage stealing decisions.  This is OK, as page
stealing never uses MIGRATE_RESERVE as a fallback, and also takes care
to leave all MIGRATE_CMA pages on the correct freelist.

Therefore, as an additional benefit, the call to
get_pageblock_migratetype() from rmqueue_bulk() when CMA is enabled, can
be removed completely.  This relies on the fact that MIGRATE_CMA
pageblocks are created only during system init, and the above.  The
related is_migrate_isolate() check is also unnecessary, as memory
isolation has other ways to move pages between freelists, and drain pcp
lists containing pages that should be isolated.  The buffered_rmqueue()
can also benefit from calling get_freepage_migratetype() instead of
get_pageblock_migratetype().

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Yong-Taek Lee <ytk.lee@samsung.com>
Reported-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Suggested-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Suggested-by: Mel Gorman <mgorman@suse.de>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: "Wang, Yalin" <Yalin.Wang@sonymobile.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:00 -07:00
Vladimir Davydov 03afc0e25f slab: get_online_mems for kmem_cache_{create,destroy,shrink}
When we create a sl[au]b cache, we allocate kmem_cache_node structures
for each online NUMA node.  To handle nodes taken online/offline, we
register memory hotplug notifier and allocate/free kmem_cache_node
corresponding to the node that changes its state for each kmem cache.

To synchronize between the two paths we hold the slab_mutex during both
the cache creationg/destruction path and while tuning per-node parts of
kmem caches in memory hotplug handler, but that's not quite right,
because it does not guarantee that a newly created cache will have all
kmem_cache_nodes initialized in case it races with memory hotplug.  For
instance, in case of slub:

    CPU0                            CPU1
    ----                            ----
    kmem_cache_create:              online_pages:
     __kmem_cache_create:            slab_memory_callback:
                                      slab_mem_going_online_callback:
                                       lock slab_mutex
                                       for each slab_caches list entry
                                           allocate kmem_cache node
                                       unlock slab_mutex
      lock slab_mutex
      init_kmem_cache_nodes:
       for_each_node_state(node, N_NORMAL_MEMORY)
           allocate kmem_cache node
      add kmem_cache to slab_caches list
      unlock slab_mutex
                                    online_pages (continued):
                                     node_states_set_node

As a result we'll get a kmem cache with not all kmem_cache_nodes
allocated.

To avoid issues like that we should hold get/put_online_mems() during
the whole kmem cache creation/destruction/shrink paths, just like we
deal with cpu hotplug.  This patch does the trick.

Note, that after it's applied, there is no need in taking the slab_mutex
for kmem_cache_shrink any more, so it is removed from there.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:59 -07:00
Vladimir Davydov bfc8c90139 mem-hotplug: implement get/put_online_mems
kmem_cache_{create,destroy,shrink} need to get a stable value of
cpu/node online mask, because they init/destroy/access per-cpu/node
kmem_cache parts, which can be allocated or destroyed on cpu/mem
hotplug.  To protect against cpu hotplug, these functions use
{get,put}_online_cpus.  However, they do nothing to synchronize with
memory hotplug - taking the slab_mutex does not eliminate the
possibility of race as described in patch 2.

What we need there is something like get_online_cpus, but for memory.
We already have lock_memory_hotplug, which serves for the purpose, but
it's a bit of a hammer right now, because it's backed by a mutex.  As a
result, it imposes some limitations to locking order, which are not
desirable, and can't be used just like get_online_cpus.  That's why in
patch 1 I substitute it with get/put_online_mems, which work exactly
like get/put_online_cpus except they block not cpu, but memory hotplug.

[ v1 can be found at https://lkml.org/lkml/2014/4/6/68.  I NAK'ed it by
  myself, because it used an rw semaphore for get/put_online_mems,
  making them dead lock prune.  ]

This patch (of 2):

{un}lock_memory_hotplug, which is used to synchronize against memory
hotplug, is currently backed by a mutex, which makes it a bit of a
hammer - threads that only want to get a stable value of online nodes
mask won't be able to proceed concurrently.  Also, it imposes some
strong locking ordering rules on it, which narrows down the set of its
usage scenarios.

This patch introduces get/put_online_mems, which are the same as
get/put_online_cpus, but for memory hotplug, i.e.  executing a code
inside a get/put_online_mems section will guarantee a stable value of
online nodes, present pages, etc.

lock_memory_hotplug()/unlock_memory_hotplug() are removed altogether.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:59 -07:00
Vladimir Davydov e8d9df3aba memcg: un-export __memcg_kmem_get_cache
It is only used in slab and should not be used anywhere else so there is
no need in exporting it.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:59 -07:00
Mel Gorman 5f7a75acdb mm: page_alloc: do not cache reclaim distances
pgdat->reclaim_nodes tracks if a remote node is allowed to be reclaimed
by zone_reclaim due to its distance.  As it is expected that
zone_reclaim_mode will be rarely enabled it is unreasonable for all
machines to take a penalty.  Fortunately, the zone_reclaim_mode() path
is already slow and it is the path that takes the hit.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:59 -07:00
Mel Gorman 4f9b16a647 mm: disable zone_reclaim_mode by default
When it was introduced, zone_reclaim_mode made sense as NUMA distances
punished and workloads were generally partitioned to fit into a NUMA
node.  NUMA machines are now common but few of the workloads are
NUMA-aware and it's routine to see major performance degradation due to
zone_reclaim_mode being enabled but relatively few can identify the
problem.

Those that require zone_reclaim_mode are likely to be able to detect
when it needs to be enabled and tune appropriately so lets have a
sensible default for the bulk of users.

This patch (of 2):

zone_reclaim_mode causes processes to prefer reclaiming memory from
local node instead of spilling over to other nodes.  This made sense
initially when NUMA machines were almost exclusively HPC and the
workload was partitioned into nodes.  The NUMA penalties were
sufficiently high to justify reclaiming the memory.  On current machines
and workloads it is often the case that zone_reclaim_mode destroys
performance but not all users know how to detect this.  Favour the
common case and disable it by default.  Users that are sophisticated
enough to know they need zone_reclaim_mode will detect it.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:59 -07:00
Luiz Capitulino 944d9fec8d hugetlb: add support for gigantic page allocation at runtime
HugeTLB is limited to allocating hugepages whose size are less than
MAX_ORDER order.  This is so because HugeTLB allocates hugepages via the
buddy allocator.  Gigantic pages (that is, pages whose size is greater
than MAX_ORDER order) have to be allocated at boottime.

However, boottime allocation has at least two serious problems.  First,
it doesn't support NUMA and second, gigantic pages allocated at boottime
can't be freed.

This commit solves both issues by adding support for allocating gigantic
pages during runtime.  It works just like regular sized hugepages,
meaning that the interface in sysfs is the same, it supports NUMA, and
gigantic pages can be freed.

For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G
gigantic pages on node 1, one can do:

 # echo 2 > \
   /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages

And to free them all:

 # echo 0 > \
   /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages

The one problem with gigantic page allocation at runtime is that it
can't be serviced by the buddy allocator.  To overcome that problem,
this commit scans all zones from a node looking for a large enough
contiguous region.  When one is found, it's allocated by using CMA, that
is, we call alloc_contig_range() to do the actual allocation.  For
example, on x86_64 we scan all zones looking for a 1GB contiguous
region.  When one is found, it's allocated by alloc_contig_range().

One expected issue with that approach is that such gigantic contiguous
regions tend to vanish as runtime goes by.  The best way to avoid this
for now is to make gigantic page allocations very early during system
boot, say from a init script.  Other possible optimization include using
compaction, which is supported by CMA but is not explicitly used by this
commit.

It's also important to note the following:

 1. Gigantic pages allocated at boottime by the hugepages= command-line
    option can be freed at runtime just fine

 2. This commit adds support for gigantic pages only to x86_64. The
    reason is that I don't have access to nor experience with other archs.
    The code is arch indepedent though, so it should be simple to add
    support to different archs

 3. I didn't add support for hugepage overcommit, that is allocating
    a gigantic page on demand when
   /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't
   think it's reasonable to do the hard and long work required for
   allocating a gigantic page at fault time. But it should be simple
   to add this if wanted

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:59 -07:00
Luiz Capitulino 1cac6f2c07 hugetlb: move helpers up in the file
Next commit will add new code which will want to call
for_each_node_mask_to_alloc() macro.  Move it, its buddy
for_each_node_mask_to_free() and their dependencies up in the file so the
new code can use them.  This is just code movement, no logic change.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Reviewed-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:59 -07:00
Luiz Capitulino a7407a27c2 hugetlb: update_and_free_page(): don't clear PG_reserved bit
Hugepages pages never get the PG_reserved bit set, so don't clear it.

However, note that if the bit gets mistakenly set free_pages_check() will
catch it.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:59 -07:00
Luiz Capitulino bae7f4ae14 hugetlb: add hstate_is_gigantic()
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Reviewed-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:59 -07:00
Luiz Capitulino 2906dd5283 hugetlb: prep_compound_gigantic_page(): drop __init marker
The HugeTLB subsystem uses the buddy allocator to allocate hugepages
during runtime.  This means that hugepages allocation during runtime is
limited to MAX_ORDER order.  For archs supporting gigantic pages (that
is, page sizes greater than MAX_ORDER), this in turn means that those
pages can't be allocated at runtime.

HugeTLB supports gigantic page allocation during boottime, via the boot
allocator.  To this end the kernel provides the command-line options
hugepagesz= and hugepages=, which can be used to instruct the kernel to
allocate N gigantic pages during boot.

For example, x86_64 supports 2M and 1G hugepages, but only 2M hugepages
can be allocated and freed at runtime.  If one wants to allocate 1G
gigantic pages, this has to be done at boot via the hugepagesz= and
hugepages= command-line options.

Now, gigantic page allocation at boottime has two serious problems:

 1. Boottime allocation is not NUMA aware. On a NUMA machine the kernel
    evenly distributes boottime allocated hugepages among nodes.

    For example, suppose you have a four-node NUMA machine and want
    to allocate four 1G gigantic pages at boottime. The kernel will
    allocate one gigantic page per node.

    On the other hand, we do have users who want to be able to specify
    which NUMA node gigantic pages should allocated from. So that they
    can place virtual machines on a specific NUMA node.

 2. Gigantic pages allocated at boottime can't be freed

At this point it's important to observe that regular hugepages allocated
at runtime don't have those problems.  This is so because HugeTLB
interface for runtime allocation in sysfs supports NUMA and runtime
allocated pages can be freed just fine via the buddy allocator.

This series adds support for allocating gigantic pages at runtime.  It
does so by allocating gigantic pages via CMA instead of the buddy
allocator.  Releasing gigantic pages is also supported via CMA.  As this
series builds on top of the existing HugeTLB interface, it makes gigantic
page allocation and releasing just like regular sized hugepages.  This
also means that NUMA support just works.

For example, to allocate two 1G gigantic pages on node 1, one can do:

 # echo 2 > \
   /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages

And, to release all gigantic pages on the same node:

 # echo 0 > \
   /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages

Please, refer to patch 5/5 for full technical details.

Finally, please note that this series is a follow up for a previous series
that tried to extend the command-line options set to be NUMA aware:

 http://marc.info/?l=linux-mm&m=139593335312191&w=2

During the discussion of that series it was agreed that having runtime
allocation support for gigantic pages was a better solution.

This patch (of 5):

This function is going to be used by non-init code in a future
commit.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:58 -07:00
Duan Jiong 14bd5b458b mm/mmap.c: replace IS_ERR and PTR_ERR with PTR_ERR_OR_ZERO
Fix a coccinelle error regarding usage of IS_ERR and PTR_ERR instead of
PTR_ERR_OR_ZERO.

Signed-off-by: Duan Jiong <duanj.fnst@cn.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>
2014-06-04 16:53:58 -07:00
Vladimir Davydov cea371f4f3 slab: document kmalloc_order
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:58 -07:00
Johannes Weiner 3dae7fec5e mm: memcontrol: remove hierarchy restrictions for swappiness and oom_control
Per-memcg swappiness and oom killing can currently not be tweaked on a
memcg that is part of a hierarchy, but not the root of that hierarchy.
Users have complained that they can't configure this when they turned on
hierarchy mode.  In fact, with hierarchy mode becoming the default, this
restriction disables the tunables entirely.

But there is no good reason for this restriction.  The settings for
swappiness and OOM killing are taken from whatever memcg whose limit
triggered reclaim and OOM invocation, regardless of its position in the
hierarchy tree.

Allow setting swappiness on any group.  The knob on the root memcg
already reads the global VM swappiness, make it writable as well.

Allow disabling the OOM killer on any non-root memcg.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:58 -07:00
Sebastian Ott 8bf8fcb076 mm/mempool: warn about __GFP_ZERO usage
Memory obtained via mempool_alloc is not always zeroed even when
called with __GFP_ZERO. Add a note and VM_BUG_ON statement to make
that clear.

[akpm@linux-foundation.org: use VM_WARN_ON_ONCE]
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:58 -07:00