Commit Graph

9542 Commits

Author SHA1 Message Date
Chen Gang c9d13f5fc7 mm/mmap.c:insert_vm_struct(): check for failure before setting values
There's no point in initializing vma->vm_pgoff if the insertion attempt
will be failing anyway.  Run the checks before performing the
initialization.

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Petr Mladek bde43c6c9f mm/khugepaged: allow interruption of allocation sleep again
Commit 1dfb059b94 ("thp: reduce khugepaged freezing latency") fixed
khugepaged to do not block a system suspend.  But the result is that it
could not get interrupted before the given timeout because the condition
for the wait event is "false".

This patch puts back the original approach but it uses
freezable_schedule_timeout_interruptible() instead of
schedule_timeout_interruptible().  It does the right thing.  I am pretty
sure that the freezable variant was not used in the original fix only
because it was not available at that time.

The regression has been there for ages.  It was not critical.  It just
did the allocation throttling a little bit more aggressively.

I found this problem when converting the kthread to kthread worker API
and trying to understand the code.

This bug is thought to have minimal userspace-visible impact.  Somebody
could set a high alloc_sleep value by mistake, and then try to fix it
back, but khugepaged would keep sleeping until the high value expires.

Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Alexander Kuleshov c115393151 mm/memblock.c: fiy typos in comments
s/succees/success/

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Joonsoo Kim 1a16718cf7 mm/compaction: correct to flush migrated pages if pageblock skip happens
We cache isolate_start_pfn before entering isolate_migratepages().  If
pageblock is skipped in isolate_migratepages() due to whatever reason,
cc->migrate_pfn can be far from isolate_start_pfn hence we flush pages
that were freed.  For example, the following scenario can be possible:

- assume order-9 compaction, pageblock order is 9
- start_isolate_pfn is 0x200
- isolate_migratepages()
  - skip a number of pageblocks
  - start to isolate from pfn 0x600
  - cc->migrate_pfn = 0x620
  - return
- last_migrated_pfn is set to 0x200
- check flushing condition
  - current_block_start is set to 0x600
  - last_migrated_pfn < current_block_start then do useless flush

This wrong flush would not help the performance and success rate so this
patch tries to fix it.  One simple way to know the exact position where
we start to isolate migratable pages is that we cache it in
isolate_migratepages() before entering actual isolation.  This patch
implements that and fixes the problem.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Vlastimil Babka 96db800f5d mm: rename alloc_pages_exact_node() to __alloc_pages_node()
alloc_pages_exact_node() was introduced in commit 6484eb3e2a ("page
allocator: do not check NUMA node ID when the caller knows the node is
valid") as an optimized variant of alloc_pages_node(), that doesn't
fallback to current node for nid == NUMA_NO_NODE.  Unfortunately the
name of the function can easily suggest that the allocation is
restricted to the given node and fails otherwise.  In truth, the node is
only preferred, unless __GFP_THISNODE is passed among the gfp flags.

The misleading name has lead to mistakes in the past, see for example
commits 5265047ac3 ("mm, thp: really limit transparent hugepage
allocation to local node") and b360edb43f ("mm, mempolicy:
migrate_to_node should only migrate to node").

Another issue with the name is that there's a family of
alloc_pages_exact*() functions where 'exact' means exact size (instead
of page order), which leads to more confusion.

To prevent further mistakes, this patch effectively renames
alloc_pages_exact_node() to __alloc_pages_node() to better convey that
it's an optimized variant of alloc_pages_node() not intended for general
usage.  Both functions get described in comments.

It has been also considered to really provide a convenience function for
allocations restricted to a node, but the major opinion seems to be that
__GFP_THISNODE already provides that functionality and we shouldn't
duplicate the API needlessly.  The number of users would be small
anyway.

Existing callers of alloc_pages_exact_node() are simply converted to
call __alloc_pages_node(), with the exception of sba_alloc_coherent()
which open-codes the check for NUMA_NO_NODE, so it is converted to use
alloc_pages_node() instead.  This means it no longer performs some
VM_BUG_ON checks, and since the current check for nid in
alloc_pages_node() uses a 'nid < 0' comparison (which includes
NUMA_NO_NODE), it may hide wrong values which would be previously
exposed.

Both differences will be rectified by the next patch.

To sum up, this patch makes no functional changes, except temporarily
hiding potentially buggy callers.  Restricting the checks in
alloc_pages_node() is left for the next patch which can in turn expose
more existing buggy callers.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Robin Holt <robinmholt@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Cliff Whickman <cpw@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Hugh Dickins 7fadc82022 mm, vmscan: unlock page while waiting on writeback
This is merely a politeness: I've not found that shrink_page_list()
leads to deadlock with the page it holds locked across
wait_on_page_writeback(); but nevertheless, why hold others off by
keeping the page locked there?

And while we're at it: remove the mistaken "not " from the commentary on
this Case 3 (and a distracting blank line from Case 2, if I may).

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Jeff Layton 26f5d7609f list_lru: don't call list_lru_from_kmem if the list_head is empty
If the list_head is empty then we'll have called list_lru_from_kmem for
nothing.  Move that call inside of the list_empty if block.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Wang Kai 21cd3a6047 kmemleak: record accurate early log buffer count and report when exceeded
In log_early function, crt_early_log should also count once when
'crt_early_log >= ARRAY_SIZE(early_log)'.  Otherwise the reported count
from kmemleak_init is one less than 'actual number'.

Then, in kmemleak_init, if early_log buffer size equal actual number,
kmemleak will init sucessful, so change warning condition to
'crt_early_log > ARRAY_SIZE(early_log)'.

Signed-off-by: Wang Kai <morgan.wang@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Chen Gang e397589125 mm/mmap.c: simplify the failure return working flow
__split_vma() doesn't need out_err label, neither need initializing err.

copy_vma() can return NULL directly when kmem_cache_alloc() fails.

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Yu Zhao 44a30220bc shmem: recalculate file inode when fstat
Shmem uses shmem_recalc_inode to update i_blocks when it allocates page,
undoes range or swaps.  But mm can drop clean page without notifying
shmem.  This makes fstat sometimes return out-of-date block size.

The problem can be partially solved when we add
inode_operations->getattr which calls shmem_recalc_inode to update
i_blocks for fstat.

shmem_recalc_inode also updates counter used by statfs and
vm_committed_as.  For them the situation is not changed.  They still
suffer from the discrepancy after dropping clean page and before the
function is called by aforementioned triggers.

Signed-off-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Alexander Kuleshov 567d117b8b mm/memblock.c: rename local variable of memblock_type to 'type'
Since commit e3239ff92a ("memblock: Rename memblock_region to
memblock_type and memblock_property to memblock_region"), all local
variables of the membock_type type were renamed to 'type'.  This commit
renames all remaining local variables with the memblock_type type to the
same view.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Naoya Horiguchi 230ac719c5 mm/hwpoison: don't try to unpoison containment-failed pages
memory_failure() can be called at any page at any time, which means that
we can't eliminate the possibility of containment failure.  In such case
the best option is to leak the page intentionally (and never touch it
later.)

We have an unpoison function for testing, and it cannot handle such
containment-failed pages, which results in kernel panic (visible with
various calltraces.) So this patch suggests that we limit the
unpoisonable pages to properly contained pages and ignore any other
ones.

Testers are recommended to keep in mind that there're un-unpoisonable
pages when writing test programs.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Tested-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Wanpeng Li da1b13ccfb mm/hwpoison: fix race between soft_offline_page and unpoison_memory
Wanpeng Li reported a race between soft_offline_page() and
unpoison_memory(), which causes the following kernel panic:

   BUG: Bad page state in process bash  pfn:97000
   page:ffffea00025c0000 count:0 mapcount:1 mapping:          (null) index:0x7f4fdbe00
   flags: 0x1fffff80080048(uptodate|active|swapbacked)
   page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
   bad because of flags:
   flags: 0x40(active)
   Modules linked in: snd_hda_codec_hdmi i915 rpcsec_gss_krb5 nfsv4 dns_resolver bnep rfcomm nfsd bluetooth auth_rpcgss nfs_acl nfs rfkill lockd grace sunrpc i2c_algo_bit drm_kms_helper snd_hda_codec_realtek snd_hda_codec_generic drm snd_hda_intel fscache snd_hda_codec x86_pkg_temp_thermal coretemp kvm_intel snd_hda_core snd_hwdep kvm snd_pcm snd_seq_dummy snd_seq_oss crct10dif_pclmul snd_seq_midi crc32_pclmul snd_seq_midi_event ghash_clmulni_intel snd_rawmidi aesni_intel lrw gf128mul snd_seq glue_helper ablk_helper snd_seq_device cryptd fuse snd_timer dcdbas serio_raw mei_me parport_pc snd mei ppdev i2c_core video lp soundcore parport lpc_ich shpchp mfd_core ext4 mbcache jbd2 sd_mod e1000e ahci ptp libahci crc32c_intel libata pps_core
   CPU: 3 PID: 2211 Comm: bash Not tainted 4.2.0-rc5-mm1+ #45
   Hardware name: Dell Inc. OptiPlex 7020/0F5C5X, BIOS A03 01/08/2015
   Call Trace:
     dump_stack+0x48/0x5c
     bad_page+0xe6/0x140
     free_pages_prepare+0x2f9/0x320
     ? uncharge_list+0xdd/0x100
     free_hot_cold_page+0x40/0x170
     __put_single_page+0x20/0x30
     put_page+0x25/0x40
     unmap_and_move+0x1a6/0x1f0
     migrate_pages+0x100/0x1d0
     ? kill_procs+0x100/0x100
     ? unlock_page+0x6f/0x90
     __soft_offline_page+0x127/0x2a0
     soft_offline_page+0xa6/0x200

This race is explained like below:

  CPU0                    CPU1

  soft_offline_page
  __soft_offline_page
  TestSetPageHWPoison
                        unpoison_memory
                        PageHWPoison check (true)
                        TestClearPageHWPoison
                        put_page    -> release refcount held by get_hwpoison_page in unpoison_memory
                        put_page    -> release refcount held by isolate_lru_page in __soft_offline_page
  migrate_pages

The second put_page() releases refcount held by isolate_lru_page() which
will lead to unmap_and_move() releases the last refcount of page and w/
mapcount still 1 since try_to_unmap() is not called if there is only one
user map the page.  Anyway, the page refcount and mapcount will still
mess if the page is mapped by multiple users.

This race was introduced by commit 4491f71260 ("mm/memory-failure: set
PageHWPoison before migrate_pages()"), which focuses on preventing the
reuse of successfully migrated page.  Before this commit we prevent the
reuse by changing the migratetype to MIGRATE_ISOLATE during soft
offlining, which has the following problems, so simply reverting the
commit is not a best option:

  1) it doesn't eliminate the reuse completely, because
     set_migratetype_isolate() can fail to set MIGRATE_ISOLATE to the
     target page if the pageblock of the page contains one or more
     unmovable pages (i.e.  has_unmovable_pages() returns true).

  2) the original code changes migratetype to MIGRATE_ISOLATE
     forcibly, and sets it to MIGRATE_MOVABLE forcibly after soft offline,
     regardless of the original migratetype state, which could impact
     other subsystems like memory hotplug or compaction.

This patch moves PageSetHWPoison just after put_page() in
unmap_and_move(), which closes up the reported race window and minimizes
another race window b/w SetPageHWPoison and reallocation (which causes
the reuse of soft-offlined page.) The latter race window still exists
but it's acceptable, because it's rare and effectively the same as
ordinary "containment failure" case even if it happens, so keep the
window open is acceptable.

Fixes: 4491f71260 ("mm/memory-failure: set PageHWPoison before migrate_pages()")
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: Wanpeng Li <wanpeng.li@hotmail.com>
Tested-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Naoya Horiguchi 8e30456b6c mm/hwpoison: introduce num_poisoned_pages wrappers
num_poisoned_pages counter will be changed outside mm/memory-failure.c
by a subsequent patch, so this patch prepares wrappers to manipulate it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Tested-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Wanpeng Li 665d9da7f0 mm/hwpoison: replace most of put_page in memory error handling by put_hwpoison_page
Replace most instances of put_page() in memory error handling with
put_hwpoison_page().

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.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>
2015-09-08 15:35:28 -07:00
Wanpeng Li be91748fa6 mm/hwpoison: fix refcount of THP head page in no-injection case
Hwpoison injection takes a refcount of target page and another refcount
of head page of THP if the target page is the tail page of a THP.
However, current code doesn't release the refcount of head page if the
THP is not supported to be injected wrt hwpoison filter.

Fix it by reducing the refcount of head page if the target page is the
tail page of a THP and it is not supported to be injected.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Acked-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>
2015-09-08 15:35:28 -07:00
Wanpeng Li 94bf4ec84a mm/hwpoison: introduce put_hwpoison_page to put refcount for memory error handling
Introduce put_hwpoison_page to put refcount for memory error handling.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Suggested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-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>
2015-09-08 15:35:28 -07:00
Wanpeng Li 1e0e635be8 mm/hwpoison: fix PageHWPoison test/set race
There is a race between madvise_hwpoison path and memory_failure:

 CPU0					CPU1

madvise_hwpoison
get_user_pages_fast
PageHWPoison check (false)
					memory_failure
					TestSetPageHWPoison
soft_offline_page
PageHWPoison check (true)
return -EBUSY (without put_page)

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Suggested-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>
2015-09-08 15:35:28 -07:00
Wanpeng Li 7d1900c744 mm/hwpoison: fix failure to split thp w/ refcount held
THP pages will get a refcount in madvise_hwpoison() w/
MF_COUNT_INCREASED flag, however, the refcount is still held when fail
to split THP pages.

Fix it by reducing the refcount of THP pages when fail to split THP.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.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>
2015-09-08 15:35:28 -07:00
Mark Salter 6b0f68e32e mm: add utility for early copy from unmapped ram
When booting an arm64 kernel w/initrd using UEFI/grub, use of mem= will
likely cut off part or all of the initrd.  This leaves it outside the
kernel linear map which leads to failure when unpacking.  The x86 code
has a similar need to relocate an initrd outside of mapped memory in
some cases.

The current x86 code uses early_memremap() to copy the original initrd
from unmapped to mapped RAM.  This patchset creates a generic
copy_from_early_mem() utility based on that x86 code and has arm64 and
x86 share it in their respective initrd relocation code.

This patch (of 3):

In some early boot circumstances, it may be necessary to copy from RAM
outside the kernel linear mapping to mapped RAM.  The need to relocate
an initrd is one example in the x86 code.  This patch creates a helper
function based on current x86 code.

Signed-off-by: Mark Salter <msalter@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.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>
2015-09-08 15:35:28 -07:00
Vlastimil Babka 9fcd6d2e05 mm, compaction: skip compound pages by order in free scanner
The compaction free scanner is looking for PageBuddy() pages and
skipping all others.  For large compound pages such as THP or hugetlbfs,
we can save a lot of iterations if we skip them at once using their
compound_order().  This is generally unsafe and we can read a bogus
value of order due to a race, but if we are careful, the only danger is
skipping too much.

When tested with stress-highalloc from mmtests on 4GB system with 1GB
hugetlbfs pages, the vmstat compact_free_scanned count decreased by at
least 15%.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: 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: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Vlastimil Babka 29c0dde830 mm, compaction: always skip all compound pages by order in migrate scanner
The compaction migrate scanner tries to skip THP pages by their order,
to reduce number of iterations for pages it cannot isolate.  The check
is only done if PageLRU() is true, which means it applies to THP pages,
but not e.g.  hugetlbfs pages or any other non-LRU compound pages, which
we have to iterate by base pages.

This limitation comes from the assumption that it's only safe to read
compound_order() when we have the zone's lru_lock and THP cannot be
split under us.  But the only danger (after filtering out order values
that are not below MAX_ORDER, to prevent overflows) is that we skip too
much or too little after reading a bogus compound_order() due to a rare
race.  This is the same reasoning as patch 99c0fd5e51 ("mm,
compaction: skip buddy pages by their order in the migrate scanner")
introduced for unsafely reading PageBuddy() order.

After this patch, all pages are tested for PageCompound() and we skip
them by compound_order().  The test is done after the test for
balloon_page_movable() as we don't want to assume if balloon pages (or
other pages with own isolation and migration implementation if a generic
API gets implemented) are compound or not.

When tested with stress-highalloc from mmtests on 4GB system with 1GB
hugetlbfs pages, the vmstat compact_migrate_scanned count decreased by
15%.

[kirill.shutemov@linux.intel.com: change PageTransHuge checks to PageCompound for different series was squashed here]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: 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: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Vlastimil Babka 02333641e2 mm, compaction: encapsulate resetting cached scanner positions
Reseting the cached compaction scanner positions is now open-coded in
__reset_isolation_suitable() and compact_finished().  Encapsulate the
functionality in a new function reset_cached_positions().

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>
Acked-by: 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: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Vlastimil Babka f5f61a320b mm, compaction: simplify handling restart position in free pages scanner
Handling the position where compaction free scanner should restart
(stored in cc->free_pfn) got more complex with commit e14c720efd ("mm,
compaction: remember position within pageblock in free pages scanner").
Currently the position is updated in each loop iteration of
isolate_freepages(), although it should be enough to update it only when
breaking from the loop.  There's also an extra check outside the loop
updates the position in case we have met the migration scanner.

This can be simplified if we move the test for having isolated enough
from the for-loop header next to the test for contention, and
determining the restart position only in these cases.  We can reuse the
isolate_start_pfn variable for this instead of setting cc->free_pfn
directly.  Outside the loop, we can simply set cc->free_pfn to current
value of isolate_start_pfn without any extra check.

Also add a VM_BUG_ON to catch possible mistake in the future, in case we
later add a new condition that terminates isolate_freepages_block()
prematurely without also considering the condition in
isolate_freepages().

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.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: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Vlastimil Babka f2849aa09d mm, compaction: more robust check for scanners meeting
Assorted compaction cleanups and optimizations.  The interesting patches
are 4 and 5.  In 4, skipping of compound pages in single iteration is
improved for migration scanner, so it works also for !PageLRU compound
pages such as hugetlbfs, slab etc.  Patch 5 introduces this kind of
skipping in the free scanner.  The trick is that we can read
compound_order() without any protection, if we are careful to filter out
values larger than MAX_ORDER.  The only danger is that we skip too much.
The same trick was already used for reading the freepage order in the
migrate scanner.

To demonstrate improvements of Patches 4 and 5 I've run stress-highalloc
from mmtests, set to simulate THP allocations (including __GFP_COMP) on
a 4GB system where 1GB was occupied by hugetlbfs pages.  I'll include
just the relevant stats:

                               Patch 3     Patch 4     Patch 5

Compaction stalls                 7523        7529        7515
Compaction success                 323         304         322
Compaction failures               7200        7224        7192
Page migrate success            247778      264395      240737
Page migrate failure             15358       33184       21621
Compaction pages isolated       906928      980192      909983
Compaction migrate scanned     2005277     1692805     1498800
Compaction free scanned       13255284    11539986     9011276
Compaction cost                    288         305         277

With 5 iterations per patch, the results are still noisy, but we can see
that Patch 4 does reduce migrate_scanned by 15% thanks to skipping the
hugetlbfs pages at once.  Interestingly, free_scanned is also reduced
and I have no idea why.  Patch 5 further reduces free_scanned as
expected, by 15%.  Other stats are unaffected modulo noise.

[1] https://lkml.org/lkml/2015/1/19/158

This patch (of 5):

Compaction should finish when the migration and free scanner meet, i.e.
they reach the same pageblock.  Currently however, the test in
compact_finished() simply just compares the exact pfns, which may yield
a false negative when the free scanner position is in the middle of a
pageblock and the migration scanner reaches the begining of the same
pageblock.

This hasn't been a problem until commit e14c720efd ("mm, compaction:
remember position within pageblock in free pages scanner") allowed the
free scanner position to be in the middle of a pageblock between
invocations.  The hot-fix 1d5bfe1ffb ("mm, compaction: prevent
infinite loop in compact_zone") prevented the issue by adding a special
check in the migration scanner to satisfy the current detection of
scanners meeting.

However, the proper fix is to make the detection more robust.  This
patch introduces the compact_scanners_met() function that returns true
when the free scanner position is in the same or lower pageblock than
the migration scanner.  The special case in isolate_migratepages()
introduced by 1d5bfe1ffb is removed.

Suggested-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Sean O. Stalley fa23f56d90 mm: add support for __GFP_ZERO flag to dma_pool_alloc()
Currently a call to dma_pool_alloc() with a ___GFP_ZERO flag returns a
non-zeroed memory region.

This patchset adds support for the __GFP_ZERO flag to dma_pool_alloc(),
adds 2 wrapper functions for allocing zeroed memory from a pool, and
provides a coccinelle script for finding & replacing instances of
dma_pool_alloc() followed by memset(0) with a single dma_pool_zalloc()
call.

There was some concern that this always calls memset() to zero, instead
of passing __GFP_ZERO into the page allocator.
[https://lkml.org/lkml/2015/7/15/881]

I ran a test on my system to get an idea of how often dma_pool_alloc()
calls into pool_alloc_page().

After Boot:	[   30.119863] alloc_calls:541, page_allocs:7
After an hour:	[ 3600.951031] alloc_calls:9566, page_allocs:12
After copying 1GB file onto a USB drive:
		[ 4260.657148] alloc_calls:17225, page_allocs:12

It doesn't look like dma_pool_alloc() calls down to the page allocator
very often (at least on my system).

This patch (of 4):

Currently the __GFP_ZERO flag is ignored by dma_pool_alloc().
Make dma_pool_alloc() zero the memory if this flag is set.

Signed-off-by: Sean O. Stalley <sean.stalley@intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Gilles Muller <Gilles.Muller@lip6.fr>
Cc: Nicolas Palix <nicolas.palix@imag.fr>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Jaewon Kim c54839a722 vmscan: fix increasing nr_isolated incurred by putback unevictable pages
reclaim_clean_pages_from_list() assumes that shrink_page_list() returns
number of pages removed from the candidate list.  But shrink_page_list()
puts back mlocked pages without passing it to caller and without
counting as nr_reclaimed.  This increases nr_isolated.

To fix this, this patch changes shrink_page_list() to pass unevictable
pages back to caller.  Caller will take care those pages.

Minchan said:

It fixes two issues.

1. With unevictable page, cma_alloc will be successful.

Exactly speaking, cma_alloc of current kernel will fail due to
unevictable pages.

2. fix leaking of NR_ISOLATED counter of vmstat

With it, too_many_isolated works.  Otherwise, it could make hang until
the process get SIGKILL.

Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Vladimir Davydov 0b802f101d mm: vmscan: never isolate more pages than necessary
If transparent huge pages are enabled, we can isolate many more pages
than we actually need to scan, because we count both single and huge
pages equally in isolate_lru_pages().

Since commit 5bc7b8aca9 ("mm: thp: add split tail pages to shrink
page list in page reclaim"), we scan all the tail pages immediately
after a huge page split (see shrink_page_list()).  As a result, we can
reclaim up to SWAP_CLUSTER_MAX * HPAGE_PMD_NR (512 MB) in one run!

This is easy to catch on memcg reclaim with zswap enabled.  The latter
makes swapout instant so that if we happen to scan an unreferenced huge
page we will evict both its head and tail pages immediately, which is
likely to result in excessive reclaim.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Chris Metcalf 1b4ace4141 bootmem: avoid freeing to bootmem after bootmem is done
Bootmem isn't popular any more, but some architectures still use it, and
freeing to bootmem after calling free_all_bootmem_core() can end up
scribbling over random memory.  Instead, make sure the kernel generates
a warning in this case by ensuring the node_bootmem_map field is
non-NULL when are freeing or marking bootmem.

An instance of this bug was just fixed in the tile architecture ("tile:
use free_bootmem_late() for initrd") and catching this case more widely
seems like a good thing.

Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Paul McQuade <paulmcquad@gmail.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Naoya Horiguchi c5b4e1b02f mm, page_isolation: make set/unset_migratetype_isolate() file-local
Nowaday, set/unset_migratetype_isolate() is defined and used only in
mm/page_isolation, so let's limit the scope within the file.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Aristeu Rozanski acda0c3340 mm/mempolicy.c: get rid of duplicated check for vma(VM_PFNMAP) in queue_pages_range()
This check was introduced as part of
   6f4576e368 ("mempolicy: apply page table walker on queue_pages_range()")

which got duplicated by
   48684a65b4 ("mm: pagewalk: fix misbehavior of walk_page_range for vma(VM_PFNMAP)")

by reintroducing it earlier on queue_page_test_walk()

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.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>
2015-09-08 15:35:28 -07:00
Tang Chen 95cf82ecc1 mem-hotplug: handle node hole when initializing numa_meminfo.
When parsing SRAT, all memory ranges are added into numa_meminfo.  In
numa_init(), before entering numa_cleanup_meminfo(), all possible memory
ranges are in numa_meminfo.  And numa_cleanup_meminfo() removes all
ranges over max_pfn or empty.

But, this only works if the nodes are continuous.  Let's have a look at
the following example:

We have an SRAT like this:
SRAT: Node 0 PXM 0 [mem 0x00000000-0x5fffffff]
SRAT: Node 0 PXM 0 [mem 0x100000000-0x1ffffffffff]
SRAT: Node 1 PXM 1 [mem 0x20000000000-0x3ffffffffff]
SRAT: Node 4 PXM 2 [mem 0x40000000000-0x5ffffffffff] hotplug
SRAT: Node 5 PXM 3 [mem 0x60000000000-0x7ffffffffff] hotplug
SRAT: Node 2 PXM 4 [mem 0x80000000000-0x9ffffffffff] hotplug
SRAT: Node 3 PXM 5 [mem 0xa0000000000-0xbffffffffff] hotplug
SRAT: Node 6 PXM 6 [mem 0xc0000000000-0xdffffffffff] hotplug
SRAT: Node 7 PXM 7 [mem 0xe0000000000-0xfffffffffff] hotplug

On boot, only node 0,1,2,3 exist.

And the numa_meminfo will look like this:
numa_meminfo.nr_blks = 9
1. on node 0: [0, 60000000]
2. on node 0: [100000000, 20000000000]
3. on node 1: [20000000000, 40000000000]
4. on node 4: [40000000000, 60000000000]
5. on node 5: [60000000000, 80000000000]
6. on node 2: [80000000000, a0000000000]
7. on node 3: [a0000000000, a0800000000]
8. on node 6: [c0000000000, a0800000000]
9. on node 7: [e0000000000, a0800000000]

And numa_cleanup_meminfo() will merge 1 and 2, and remove 8,9 because the
end address is over max_pfn, which is a0800000000.  But 4 and 5 are not
removed because their end addresses are less then max_pfn.  But in fact,
node 4 and 5 don't exist.

In a word, numa_cleanup_meminfo() is not able to handle holes between nodes.

Since memory ranges in node 4 and 5 are in numa_meminfo, in
numa_register_memblks(), node 4 and 5 will be mistakenly set to online.

If you run lscpu, it will show:
NUMA node0 CPU(s):     0-14,128-142
NUMA node1 CPU(s):     15-29,143-157
NUMA node2 CPU(s):
NUMA node3 CPU(s):
NUMA node4 CPU(s):     62-76,190-204
NUMA node5 CPU(s):     78-92,206-220

In this patch, we use memblock_overlaps_region() to check if ranges in
numa_meminfo overlap with ranges in memory_block.  Since memory_block
contains all available memory at boot time, if they overlap, it means the
ranges exist.  If not, then remove them from numa_meminfo.

After this patch, lscpu will show:
NUMA node0 CPU(s):     0-14,128-142
NUMA node1 CPU(s):     15-29,143-157
NUMA node4 CPU(s):     62-76,190-204
NUMA node5 CPU(s):     78-92,206-220

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Tang Chen c5c5c9d100 mm/memblock.c: make memblock_overlaps_region() return bool.
memblock_overlaps_region() checks if the given memblock region
intersects a region in memblock.  If so, it returns the index of the
intersected region.

But its only caller is memblock_is_region_reserved(), and it returns 0
if false, non-zero if true.

Both of these should return bool.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Mike Kravetz 72079ba0df mm: madvise allow remove operation for hugetlbfs
Now that we have hole punching support for hugetlbfs, we can also
support the MADV_REMOVE interface to it.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Mike Kravetz 70c3547e36 hugetlbfs: add hugetlbfs_fallocate()
This is based on the shmem version, but it has diverged quite a bit.  We
have no swap to worry about, nor the new file sealing.  Add
synchronication via the fault mutex table to coordinate page faults,
fallocate allocation and fallocate hole punch.

What this allows us to do is move physical memory in and out of a
hugetlbfs file without having it mapped.  This also gives us the ability
to support MADV_REMOVE since it is currently implemented using
fallocate().  MADV_REMOVE lets madvise() remove pages from the middle of
a hugetlbfs file, which wasn't possible before.

hugetlbfs fallocate only operates on whole huge pages.

Based on code by Dave Hansen.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Mike Kravetz ab76ad540a hugetlbfs: New huge_add_to_page_cache helper routine
Currently, there is only a single place where hugetlbfs pages are added
to the page cache.  The new fallocate code be adding a second one, so
break the functionality out into its own helper.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Mike Kravetz d85f69b0b5 mm/hugetlb: alloc_huge_page handle areas hole punched by fallocate
Areas hole punched by fallocate will not have entries in the
region/reserve map.  However, shared mappings with min_size subpool
reservations may still have reserved pages.  alloc_huge_page needs to
handle this special case and do the proper accounting.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Mike Kravetz 1fb1b0e9ef mm/hugetlb: vma_has_reserves() needs to handle fallocate hole punch
In vma_has_reserves(), the current assumption is that reserves are
always present for shared mappings.  However, this will not be the case
with fallocate hole punch.  When punching a hole, the present page will
be deleted as well as the region/reserve map entry (and hence any
reservation).  vma_has_reserves is passed "chg" which indicates whether
or not a region/reserve map is present.  Use this to determine if
reserves are actually present or were removed via hole punch.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Mike Kravetz b5cec28d36 hugetlbfs: truncate_hugepages() takes a range of pages
Modify truncate_hugepages() to take a range of pages (start, end)
instead of simply start.  If an end value of LLONG_MAX is passed, the
current "truncate" functionality is maintained.  Existing callers are
modified to pass LLONG_MAX as end of range.  By keying off end ==
LLONG_MAX, the routine behaves differently for truncate and hole punch.
Page removal is now synchronized with page allocation via faults by
using the fault mutex table.  The hole punch case can experience the
rare region_del error and must handle accordingly.

Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in
the case where region_del returns an error.

Since the routine handles more than just the truncate case, it is
renamed to remove_inode_hugepages().  To be consistent, the routine
truncate_huge_page() is renamed remove_huge_page().

Downstream of remove_inode_hugepages(), the routine
hugetlb_unreserve_pages() is also modified to take a range of pages.
hugetlb_unreserve_pages is modified to detect an error from region_del and
pass it back to the caller.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Mike Kravetz c672c7f29f mm/hugetlb: expose hugetlb fault mutex for use by fallocate
hugetlb page faults are currently synchronized by the table of mutexes
(htlb_fault_mutex_table).  fallocate code will need to synchronize with
the page fault code when it allocates or deletes pages.  Expose
interfaces so that fallocate operations can be synchronized with page
faults.  Minor name changes to be more consistent with other global
hugetlb symbols.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Mike Kravetz feba16e25a mm/hugetlb: add region_del() to delete a specific range of entries
fallocate hole punch will want to remove a specific range of pages.  The
existing region_truncate() routine deletes all region/reserve map
entries after a specified offset.  region_del() will provide this same
functionality if the end of region is specified as LONG_MAX.  Hence,
region_del() can replace region_truncate().

Unlike region_truncate(), region_del() can return an error in the rare
case where it can not allocate memory for a region descriptor.  This
ONLY happens in the case where an existing region must be split.
Current callers passing LONG_MAX as end of range will never experience
this error and do not need to deal with error handling.  Future callers
of region_del() (such as fallocate hole punch) will need to handle this
error.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Mike Kravetz 5e9113731a mm/hugetlb: add cache of descriptors to resv_map for region_add
hugetlbfs is used today by applications that want a high degree of
control over huge page usage.  Often, large hugetlbfs files are used to
map a large number huge pages into the application processes.  The
applications know when page ranges within these large files will no
longer be used, and ideally would like to release them back to the
subpool or global pools for other uses.  The fallocate() system call
provides an interface for preallocation and hole punching within files.
This patch set adds fallocate functionality to hugetlbfs.

fallocate hole punch will want to remove a specific range of pages.
When pages are removed, their associated entries in the region/reserve
map will also be removed.  This will break an assumption in the
region_chg/region_add calling sequence.  If a new region descriptor must
be allocated, it is done as part of the region_chg processing.  In this
way, region_add can not fail because it does not need to attempt an
allocation.

To prepare for fallocate hole punch, create a "cache" of descriptors
that can be used by region_add if necessary.  region_chg will ensure
there are sufficient entries in the cache.  It will be necessary to
track the number of in progress add operations to know a sufficient
number of descriptors reside in the cache.  A new routine region_abort
is added to adjust this in progress count when add operations are
aborted.  vma_abort_reservation is also added for callers creating
reservations with vma_needs_reservation/vma_commit_reservation.

[akpm@linux-foundation.org: fix typo in comment, use more cols]
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Vlastimil Babka bb14c2c75d mm: rename and move get/set_freepage_migratetype
The pair of get/set_freepage_migratetype() functions are used to cache
pageblock migratetype for a page put on a pcplist, so that it does not
have to be retrieved again when the page is put on a free list (e.g.
when pcplists become full).  Historically it was also assumed that the
value is accurate for pages on freelists (as the functions' names
unfortunately suggest), but that cannot be guaranteed without affecting
various allocator fast paths.  It is in fact not needed and all such
uses have been removed.

The last remaining (but pointless) usage related to pages of freelists
is in move_freepages(), which this patch removes.

To prevent further confusion, rename the functions to
get/set_pcppage_migratetype() and expand their description.  Since all
the users are now in mm/page_alloc.c, move the functions there from the
shared header.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Seungho Park <seungho1.park@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Vlastimil Babka aa016d145d mm, page_isolation: remove bogus tests for isolated pages
The __test_page_isolated_in_pageblock() is used to verify whether all
pages in pageblock were either successfully isolated, or are hwpoisoned.
Two of the possible state of pages, that are tested, are however bogus
and misleading.

Both tests rely on get_freepage_migratetype(page), which however has no
guarantees about pages on freelists.  Specifically, it doesn't guarantee
that the migratetype returned by the function actually matches the
migratetype of the freelist that the page is on.  Such guarantee is not
its purpose and would have negative impact on allocator performance.

The first test checks whether the freepage_migratetype equals
MIGRATE_ISOLATE, supposedly to catch races between page isolation and
allocator activity.  These races should be fixed nowadays with
51bb1a4093 ("mm/page_alloc: add freepage on isolate pageblock to correct
buddy list") and related patches.  As explained above, the check
wouldn't be able to catch them reliably anyway.  For the same reason
false positives can happen, although they are harmless, as the
move_freepages() call would just move the page to the same freelist it's
already on.  So removing the test is not a bug fix, just cleanup.  After
this patch, we assume that all PageBuddy pages are on the correct
freelist and that the races were really fixed.  A truly reliable
verification in the form of e.g.  VM_BUG_ON() would be complicated and
is arguably not needed.

The second test (page_count(page) == 0 && get_freepage_migratetype(page)
== MIGRATE_ISOLATE) is probably supposed (the code comes from a big
memory isolation patch from 2007) to catch pages on MIGRATE_ISOLATE
pcplists.  However, pcplists don't contain MIGRATE_ISOLATE freepages
nowadays, those are freed directly to free lists, so the check is
obsolete.  Remove it as well.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Seungho Park <seungho1.park@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Michal Hocko e752eb6881 memcg: move memcg_proto_active from sock.h
The only user is sock_update_memcg which is living in memcontrol.c so it
doesn't make much sense to pollute sock.h by this inline helper.  Move it
to memcontrol.c and open code it into its only caller.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Michal Hocko a03f1f0589 memcg, tcp_kmem: check for cg_proto in sock_update_memcg
sk_prot->proto_cgroup is allowed to return NULL but sock_update_memcg
doesn't check for NULL.  The function relies on the mem_cgroup_is_root
check because we shouldn't get NULL otherwise because mem_cgroup_from_task
will always return !NULL.

All other callers are checking for NULL and we can safely replace
mem_cgroup_is_root() check by cg_proto != NULL which will be more
straightforward (proto_cgroup returns NULL for the root memcg already).

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Tejun Heo 9f2115f93b memcg: restructure mem_cgroup_can_attach()
Restructure it to lower nesting level and help the planned threadgroup
leader iteration changes.

This is pure reorganization.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.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>
2015-09-08 15:35:28 -07:00
Michal Hocko 33398cf2f3 memcg: export struct mem_cgroup
mem_cgroup structure is defined in mm/memcontrol.c currently which means
that the code outside of this file has to use external API even for
trivial access stuff.

This patch exports mm_struct with its dependencies and makes some of the
exported functions inlines.  This even helps to reduce the code size a bit
(make defconfig + CONFIG_MEMCG=y)

  text		data    bss     dec     	 hex 	filename
  12355346        1823792 1089536 15268674         e8fb42 vmlinux.before
  12354970        1823792 1089536 15268298         e8f9ca vmlinux.after

This is not much (370B) but better than nothing.

We also save a function call in some hot paths like callers of
mem_cgroup_count_vm_event which is used for accounting.

The patch doesn't introduce any functional changes.

[vdavykov@parallels.com: inline memcg_kmem_is_active]
[vdavykov@parallels.com: do not expose type outside of CONFIG_MEMCG]
[akpm@linux-foundation.org: memcontrol.h needs eventfd.h for eventfd_ctx]
[akpm@linux-foundation.org: export mem_cgroup_from_task() to modules]
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Sergey Senozhatsky 44d7175da6 mm/dmapool: allow NULL `pool' pointer in dma_pool_destroy()
dma_pool_destroy() does not tolerate a NULL dma_pool pointer argument and
performs a NULL-pointer dereference.  This requires additional attention
and effort from developers/reviewers and forces all dma_pool_destroy()
callers to do a NULL check

    if (pool)
        dma_pool_destroy(pool);

Or, otherwise, be invalid dma_pool_destroy() users.

Tweak dma_pool_destroy() and NULL-check the pointer there.

Proposed by Andrew Morton.

Link: https://lkml.org/lkml/2015/6/8/583
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Sergey Senozhatsky 4e3ca3e033 mm/mempool: allow NULL `pool' pointer in mempool_destroy()
mempool_destroy() does not tolerate a NULL mempool_t pointer argument and
performs a NULL-pointer dereference.  This requires additional attention
and effort from developers/reviewers and forces all mempool_destroy()
callers to do a NULL check

    if (pool)
        mempool_destroy(pool);

Or, otherwise, be invalid mempool_destroy() users.

Tweak mempool_destroy() and NULL-check the pointer there.

Proposed by Andrew Morton.

Link: https://lkml.org/lkml/2015/6/8/583
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Sergey Senozhatsky 3942d29918 mm/slab_common: allow NULL cache pointer in kmem_cache_destroy()
kmem_cache_destroy() does not tolerate a NULL kmem_cache pointer argument
and performs a NULL-pointer dereference.  This requires additional
attention and effort from developers/reviewers and forces all
kmem_cache_destroy() callers (200+ as of 4.1) to do a NULL check

    if (cache)
        kmem_cache_destroy(cache);

Or, otherwise, be invalid kmem_cache_destroy() users.

Tweak kmem_cache_destroy() and NULL-check the pointer there.

Proposed by Andrew Morton.

Link: https://lkml.org/lkml/2015/6/8/583
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
David Rientjes 75e8f8b24c mm, oom: remove unnecessary variable
The "killed" variable in out_of_memory() can be removed since the call to
oom_kill_process() where we should block to allow the process time to
exit is obvious.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
David Rientjes 071a4befeb mm, oom: do not panic for oom kills triggered from sysrq
Sysrq+f is used to kill a process either for debug or when the VM is
otherwise unresponsive.

It is not intended to trigger a panic when no process may be killed.

Avoid panicking the system for sysrq+f when no processes are killed.

Signed-off-by: David Rientjes <rientjes@google.com>
Suggested-by: Michal Hocko <mhocko@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
David Rientjes 54e9e29132 mm, oom: pass an oom order of -1 when triggered by sysrq
The force_kill member of struct oom_control isn't needed if an order of -1
is used instead.  This is the same as order == -1 in struct
compact_control which requires full memory compaction.

This patch introduces no functional change.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
David Rientjes 6e0fc46dc2 mm, oom: organize oom context into struct
There are essential elements to an oom context that are passed around to
multiple functions.

Organize these elements into a new struct, struct oom_control, that
specifies the context for an oom condition.

This patch introduces no functional change.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Nicholas Krause 2c0b80d463 mm: make set_recommended_min_free_kbytes() return void
This makes set_recommended_min_free_kbytes() have a return type of void as
it cannot fail.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Dave Hansen 998ef75ddb fs: do not prefault sys_write() user buffer pages
=== Short summary ====

iov_iter_fault_in_readable() works around a really rare case and we can
avoid the deadlock it addresses in another way: disable page faults and
work around copy failures by faulting after the copy in a slow path
instead of before in a hot one.

I have a little microbenchmark that does repeated, small writes to tmpfs.
This patch speeds that micro up by 6.2%.

=== Long version ===

When doing a sys_write() we have a source buffer in userspace and then a
target file page.

If both of those are the same physical page, there is a potential deadlock
that we avoid.  It would happen something like this:

1. We start the write to the file
2. Allocate page cache page and set it !Uptodate
3. Touch the userspace buffer to copy in the user data
4. Page fault (since source of the write not yet mapped)
5. Page fault code tries to lock the page and deadlocks

(more details on this below)

To avoid this, we prefault the page to guarantee that this fault does not
occur.  But, this prefault comes at a cost.  It is one of the most
expensive things that we do in a hot write() path (especially if we
compare it to the read path).  It is working around a pretty rare case.

To fix this, it's pretty simple.  We move the "prefault" code to run after
we attempt the copy.  We explicitly disable page faults _during_ the copy,
detect the copy failure, then execute the "prefault" ouside of where the
page lock needs to be held.

iov_iter_copy_from_user_atomic() actually already has an implicit
pagefault_disable() inside of it (at least on x86), but we add an explicit
one.  I don't think we can depend on every kmap_atomic() implementation to
pagefault_disable() for eternity.

===================================================

The stack trace when this happens looks like this:

  wait_on_page_bit_killable+0xc0/0xd0
  __lock_page_or_retry+0x84/0xa0
  filemap_fault+0x1ed/0x3d0
  __do_fault+0x41/0xc0
  handle_mm_fault+0x9bb/0x1210
  __do_page_fault+0x17f/0x3d0
  do_page_fault+0xc/0x10
  page_fault+0x22/0x30
  generic_perform_write+0xca/0x1a0
  __generic_file_write_iter+0x190/0x1f0
  ext4_file_write_iter+0xe9/0x460
  __vfs_write+0xaa/0xe0
  vfs_write+0xa6/0x1a0
  SyS_write+0x46/0xa0
  entry_SYSCALL_64_fastpath+0x12/0x6a
  0xffffffffffffffff

(Note, this does *NOT* happen in practice today because
 the kmap_atomic() does a pagefault_disable().  The trace
 above was obtained by taking out the pagefault_disable().)

You can trigger the deadlock with this little code snippet:

	fd = open("foo", O_RDWR);
	fdmap = mmap(NULL, len, PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0);
	write(fd, &fdmap[0], 1);

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Paul Cassella <cassella@cray.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Minchan Kim 8334b96221 mm: /proc/pid/smaps:: show proportional swap share of the mapping
We want to know per-process workingset size for smart memory management
on userland and we use swap(ex, zram) heavily to maximize memory
efficiency so workingset includes swap as well as RSS.

On such system, if there are lots of shared anonymous pages, it's really
hard to figure out exactly how many each process consumes memory(ie, rss
+ wap) if the system has lots of shared anonymous memory(e.g, android).

This patch introduces SwapPss field on /proc/<pid>/smaps so we can get
more exact workingset size per process.

Bongkyu tested it. Result is below.

1. 50M used swap
SwapTotal: 461976 kB
SwapFree: 411192 kB

$ adb shell cat /proc/*/smaps | grep "SwapPss:" | awk '{sum += $2} END {print sum}';
48236
$ adb shell cat /proc/*/smaps | grep "Swap:" | awk '{sum += $2} END {print sum}';
141184

2. 240M used swap
SwapTotal: 461976 kB
SwapFree: 216808 kB

$ adb shell cat /proc/*/smaps | grep "SwapPss:" | awk '{sum += $2} END {print sum}';
230315
$ adb shell cat /proc/*/smaps | grep "Swap:" | awk '{sum += $2} END {print sum}';
1387744

[akpm@linux-foundation.org: simplify kunmap_atomic() call]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Bongkyu Kim <bongkyu.kim@lge.com>
Tested-by: Bongkyu Kim <bongkyu.kim@lge.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Vladimir Murzin 3115aec451 memtest: remove unused header files
memtest does not require these headers to be included.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Leon Romanovsky <leon@leon.nu>
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>
2015-09-08 15:35:28 -07:00
Vladimir Murzin f373bafcad memtest: cleanup log messages
- prefer pr_info(...  to printk(KERN_INFO ...
- use %pa for phys_addr_t
- use cpu_to_be64 while printing pattern in reserve_bad_mem()

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Leon Romanovsky <leon@leon.nu>
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>
2015-09-08 15:35:28 -07:00
Vladimir Murzin 06f805965f memtest: use kstrtouint instead of simple_strtoul
Since simple_strtoul is obsolete and memtest_pattern is type of int, use
kstrtouint instead.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Leon Romanovsky <leon@leon.nu>
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>
2015-09-08 15:35:28 -07:00
Wei Yang 4fcab5f437 mm/memblock.c: WARN_ON when flags differs from overlap region
Each memblock_region has flags to indicates the type of this range. For
the overlap case, memblock_add_range() inserts the lower part and leave the
upper part as indicated in the overlapped region.

If the flags of the new range differs from the overlapped region, the
information recorded is not correct.

This patch adds a WARN_ON when the flags of the new range differs from the
overlapped region.

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Wei Yang 7f3eb55bfa mm/page_alloc.c: remove unused variable in free_area_init_core()
Commit febd5949e1 ("mm/memory hotplug: init the zone's size when
calculating node totalpages") refines the function
free_area_init_core().

After doing so, these two parameters are not used anymore.

This patch removes these two parameters.

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Cc: Gu Zheng <guz.fnst@cn.fujitsu.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>
2015-09-08 15:35:28 -07:00
Wei Yang 904a9553d4 mm/page_alloc.c: refine the calculation of highest possible node id
nr_node_ids records the highest possible node id, which is calculated by
scanning the bitmap node_states[N_POSSIBLE].  Current implementation
scan the bitmap from the beginning, which will scan the whole bitmap.

This patch reverses the order by scanning from the end with
find_last_bit().

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@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>
2015-09-08 15:35:28 -07:00
Kirill A. Shutemov 52a2b53ffd mm, dax: use i_mmap_unlock_write() in do_cow_fault()
__dax_fault() takes i_mmap_lock for write. Let's pair it with write
unlock on do_cow_fault() side.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Kirill A. Shutemov 46c043ede4 mm: take i_mmap_lock in unmap_mapping_range() for DAX
DAX is not so special: we need i_mmap_lock to protect mapping->i_mmap.

__dax_pmd_fault() uses unmap_mapping_range() shoot out zero page from
all mappings.  We need to drop i_mmap_lock there to avoid lock deadlock.

Re-aquiring the lock should be fine since we check i_size after the
point.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Kirill A. Shutemov d295e3415a dax: don't use set_huge_zero_page()
This is another place where DAX assumed that pgtable_t was a pointer.
Open code the important parts of set_huge_zero_page() in DAX and make
set_huge_zero_page() static again.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Kirill A. Shutemov da14676900 thp: fix zap_huge_pmd() for DAX
The original DAX code assumed that pgtable_t was a pointer, which isn't
true on all architectures.  Restructure the code to not rely on that
assumption.

[willy@linux.intel.com: further fixes integrated into this patch]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Kirill A. Shutemov 5b701b846a thp: decrement refcount on huge zero page if it is split
The DAX code neglected to put the refcount on the huge zero page.
Also we must notify on splits.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Matthew Wilcox 843172978b dax: fix race between simultaneous faults
If two threads write-fault on the same hole at the same time, the winner
of the race will return to userspace and complete their store, only to
have the loser overwrite their store with zeroes.  Fix this for now by
taking the i_mmap_sem for write instead of read, and do so outside the
call to get_block().  Now the loser of the race will see the block has
already been zeroed, and will not zero it again.

This severely limits our scalability.  I have ideas for improving it, but
those can wait for a later patch.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Matthew Wilcox ae18d6dcf5 thp: change insert_pfn's return type to void
It would make more sense to have all the return values from
vmf_insert_pfn_pmd() encoded in one place instead of having to follow
the convention into insert_pfn().  Suggested by Jeff Moyer.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Matthew Wilcox 5cad465d7f mm: add vmf_insert_pfn_pmd()
Similar to vm_insert_pfn(), but for PMDs rather than PTEs.  The 'vmf_'
prefix instead of 'vm_' prefix is intended to indicate that it returns a
VMF_ value rather than an errno (which would only have to be converted
into a VMF_ value anyway).

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Matthew Wilcox fc43704437 mm: export various functions for the benefit of DAX
To use the huge zero page in DAX, we need these functions exported.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Matthew Wilcox b96375f74a mm: add a pmd_fault handler
Allow non-anonymous VMAs to provide huge pages in response to a page fault.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Matthew Wilcox 4897c7655d thp: prepare for DAX huge pages
Add a vma_is_dax() helper macro to test whether the VMA is DAX, and use it
in zap_huge_pmd() and __split_huge_page_pmd().

[akpm@linux-foundation.org: fix build]
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Andrew Morton 7c41416459 dax: revert userfaultfd change
Undo the change which "userfaultfd: call handle_userfault() for
userfaultfd_missing() faults" made to set_huge_zero_page().  DAX will
need that return value.

Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Kirill A. Shutemov e1b9996b85 thp: vma_adjust_trans_huge(): adjust file-backed VMA too
This series of patches adds support for using PMD page table entries to
map DAX files.  We expect NV-DIMMs to start showing up that are many
gigabytes in size and the memory consumption of 4kB PTEs will be
astronomical.

The patch series leverages much of the Transparant Huge Pages
infrastructure, going so far as to borrow one of Kirill's patches from
his THP page cache series.

This patch (of 10):

Since we're going to have huge pages in page cache, we need to call adjust
file-backed VMA, which potentially can contain huge pages.

For now we call it for all VMAs.

Probably later we will need to introduce a flag to indicate that the VMA
has huge pages.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Acked-by: Hillf Danton <dhillf@gmail.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Oleg Nesterov ce75799b83 mremap: fix the wrong !vma->vm_file check in copy_vma()
Test-case:

	#define _GNU_SOURCE
	#include <stdio.h>
	#include <unistd.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/mman.h>
	#include <assert.h>

	void *find_vdso_vaddr(void)
	{
		FILE *perl;
		char buf[32] = {};

		perl = popen("perl -e 'open STDIN,qq|/proc/@{[getppid]}/maps|;"
				"/^(.*?)-.*vdso/ && print hex $1 while <>'", "r");
		fread(buf, sizeof(buf), 1, perl);
		fclose(perl);

		return (void *)atol(buf);
	}

	#define PAGE_SIZE	4096

	void *get_unmapped_area(void)
	{
		void *p = mmap(0, PAGE_SIZE, PROT_NONE,
				MAP_PRIVATE|MAP_ANONYMOUS, -1,0);
		assert(p != MAP_FAILED);
		munmap(p, PAGE_SIZE);
		return p;
	}

	char save[2][PAGE_SIZE];

	int main(void)
	{
		void *vdso = find_vdso_vaddr();
		void *page[2];

		assert(vdso);
		memcpy(save, vdso, sizeof (save));
		// force another fault on the next check
		assert(madvise(vdso, 2 * PAGE_SIZE, MADV_DONTNEED) == 0);

		page[0] = mremap(vdso,
				PAGE_SIZE, PAGE_SIZE, MREMAP_FIXED | MREMAP_MAYMOVE,
				get_unmapped_area());
		page[1] = mremap(vdso + PAGE_SIZE,
				PAGE_SIZE, PAGE_SIZE, MREMAP_FIXED | MREMAP_MAYMOVE,
				get_unmapped_area());

		assert(page[0] != MAP_FAILED && page[1] != MAP_FAILED);
		printf("match: %d %d\n",
			!memcmp(save[0], page[0], PAGE_SIZE),
			!memcmp(save[1], page[1], PAGE_SIZE));

		return 0;
	}

fails without this patch. Before the previous commit it gets the wrong
page, now it segfaults (which is imho better).

This is because copy_vma() wrongly assumes that if vma->vm_file == NULL
is irrelevant until the first fault which will use do_anonymous_page().
This is obviously wrong for the special mapping.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Oleg Nesterov 8a9cc3b55e mmap: fix the usage of ->vm_pgoff in special_mapping paths
Test-case:

	#include <stdio.h>
	#include <unistd.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/mman.h>
	#include <assert.h>

	void *find_vdso_vaddr(void)
	{
		FILE *perl;
		char buf[32] = {};

		perl = popen("perl -e 'open STDIN,qq|/proc/@{[getppid]}/maps|;"
				"/^(.*?)-.*vdso/ && print hex $1 while <>'", "r");
		fread(buf, sizeof(buf), 1, perl);
		fclose(perl);

		return (void *)atol(buf);
	}

	#define PAGE_SIZE	4096

	int main(void)
	{
		void *vdso = find_vdso_vaddr();
		assert(vdso);

		// of course they should differ, and they do so far
		printf("vdso pages differ: %d\n",
			!!memcmp(vdso, vdso + PAGE_SIZE, PAGE_SIZE));

		// split into 2 vma's
		assert(mprotect(vdso, PAGE_SIZE, PROT_READ) == 0);

		// force another fault on the next check
		assert(madvise(vdso, 2 * PAGE_SIZE, MADV_DONTNEED) == 0);

		// now they no longer differ, the 2nd vm_pgoff is wrong
		printf("vdso pages differ: %d\n",
			!!memcmp(vdso, vdso + PAGE_SIZE, PAGE_SIZE));

		return 0;
	}

Output:

	vdso pages differ: 1
	vdso pages differ: 0

This is because split_vma() correctly updates ->vm_pgoff, but the logic
in insert_vm_struct() and special_mapping_fault() is absolutely broken,
so the fault at vdso + PAGE_SIZE return the 1st page. The same happens
if you simply unmap the 1st page.

special_mapping_fault() does:

	pgoff = vmf->pgoff - vma->vm_pgoff;

and this is _only_ correct if vma->vm_start mmaps the first page from
->vm_private_data array.

vdso or any other user of install_special_mapping() is not anonymous,
it has the "backing storage" even if it is just the array of pages.
So we actually need to make vm_pgoff work as an offset in this array.

Note: this also allows to fix another problem: currently gdb can't access
"[vvar]" memory because in this case special_mapping_fault() doesn't work.
Now that we can use ->vm_pgoff we can implement ->access() and fix this.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Oleg Nesterov b533062854 mm: introduce vma_is_anonymous(vma) helper
special_mapping_fault() is absolutely broken.  It seems it was always
wrong, but this didn't matter until vdso/vvar started to use more than
one page.

And after this change vma_is_anonymous() becomes really trivial, it
simply checks vm_ops == NULL.  However, I do think the helper makes
sense.  There are a lot of ->vm_ops != NULL checks, the helper makes the
caller's code more understandable (self-documented) and this is more
grep-friendly.

This patch (of 3):

Preparation.  Add the new simple helper, vma_is_anonymous(vma), and change
handle_pte_fault() to use it.  It will have more users.

The name is not accurate, say a hpet_mmap()'ed vma is not anonymous.
Perhaps it should be named vma_has_fault() instead.  But it matches the
logic in mmap.c/memory.c (see next changes).  "True" just means that a
page fault will use do_anonymous_page().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
Linus Torvalds 12f03ee606 libnvdimm for 4.3:
1/ Introduce ZONE_DEVICE and devm_memremap_pages() as a generic
    mechanism for adding device-driver-discovered memory regions to the
    kernel's direct map.  This facility is used by the pmem driver to
    enable pfn_to_page() operations on the page frames returned by DAX
    ('direct_access' in 'struct block_device_operations'). For now, the
    'memmap' allocation for these "device" pages comes from "System
    RAM".  Support for allocating the memmap from device memory will
    arrive in a later kernel.
 
 2/ Introduce memremap() to replace usages of ioremap_cache() and
    ioremap_wt().  memremap() drops the __iomem annotation for these
    mappings to memory that do not have i/o side effects.  The
    replacement of ioremap_cache() with memremap() is limited to the
    pmem driver to ease merging the api change in v4.3.  Completion of
    the conversion is targeted for v4.4.
 
 3/ Similar to the usage of memcpy_to_pmem() + wmb_pmem() in the pmem
    driver, update the VFS DAX implementation and PMEM api to provide
    persistence guarantees for kernel operations on a DAX mapping.
 
 4/ Convert the ACPI NFIT 'BLK' driver to map the block apertures as
    cacheable to improve performance.
 
 5/ Miscellaneous updates and fixes to libnvdimm including support
    for issuing "address range scrub" commands, clarifying the optimal
    'sector size' of pmem devices, a clarification of the usage of the
    ACPI '_STA' (status) property for DIMM devices, and other minor
    fixes.
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Merge tag 'libnvdimm-for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm updates from Dan Williams:
 "This update has successfully completed a 0day-kbuild run and has
  appeared in a linux-next release.  The changes outside of the typical
  drivers/nvdimm/ and drivers/acpi/nfit.[ch] paths are related to the
  removal of IORESOURCE_CACHEABLE, the introduction of memremap(), and
  the introduction of ZONE_DEVICE + devm_memremap_pages().

  Summary:

   - Introduce ZONE_DEVICE and devm_memremap_pages() as a generic
     mechanism for adding device-driver-discovered memory regions to the
     kernel's direct map.

     This facility is used by the pmem driver to enable pfn_to_page()
     operations on the page frames returned by DAX ('direct_access' in
     'struct block_device_operations').

     For now, the 'memmap' allocation for these "device" pages comes
     from "System RAM".  Support for allocating the memmap from device
     memory will arrive in a later kernel.

   - Introduce memremap() to replace usages of ioremap_cache() and
     ioremap_wt().  memremap() drops the __iomem annotation for these
     mappings to memory that do not have i/o side effects.  The
     replacement of ioremap_cache() with memremap() is limited to the
     pmem driver to ease merging the api change in v4.3.

     Completion of the conversion is targeted for v4.4.

   - Similar to the usage of memcpy_to_pmem() + wmb_pmem() in the pmem
     driver, update the VFS DAX implementation and PMEM api to provide
     persistence guarantees for kernel operations on a DAX mapping.

   - Convert the ACPI NFIT 'BLK' driver to map the block apertures as
     cacheable to improve performance.

   - Miscellaneous updates and fixes to libnvdimm including support for
     issuing "address range scrub" commands, clarifying the optimal
     'sector size' of pmem devices, a clarification of the usage of the
     ACPI '_STA' (status) property for DIMM devices, and other minor
     fixes"

* tag 'libnvdimm-for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (34 commits)
  libnvdimm, pmem: direct map legacy pmem by default
  libnvdimm, pmem: 'struct page' for pmem
  libnvdimm, pfn: 'struct page' provider infrastructure
  x86, pmem: clarify that ARCH_HAS_PMEM_API implies PMEM mapped WB
  add devm_memremap_pages
  mm: ZONE_DEVICE for "device memory"
  mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h
  dax: drop size parameter to ->direct_access()
  nd_blk: change aperture mapping from WC to WB
  nvdimm: change to use generic kvfree()
  pmem, dax: have direct_access use __pmem annotation
  dax: update I/O path to do proper PMEM flushing
  pmem: add copy_from_iter_pmem() and clear_pmem()
  pmem, x86: clean up conditional pmem includes
  pmem: remove layer when calling arch_has_wmb_pmem()
  pmem, x86: move x86 PMEM API to new pmem.h header
  libnvdimm, e820: make CONFIG_X86_PMEM_LEGACY a tristate option
  pmem: switch to devm_ allocations
  devres: add devm_memremap
  libnvdimm, btt: write and validate parent_uuid
  ...
2015-09-08 14:35:59 -07:00
Linus Torvalds 752240e74d xen: features and fixes for 4.3-rc0
- Convert xen-blkfront to the multiqueue API
 - [arm] Support binding event channels to different VCPUs.
 - [x86] Support > 512 GiB in a PV guests (off by default as such a
   guest cannot be migrated with the current toolstack).
 - [x86] PMU support for PV dom0 (limited support for using perf with
   Xen and other guests).
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Merge tag 'for-linus-4.3-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen updates from David Vrabel:
 "Xen features and fixes for 4.3:

   - Convert xen-blkfront to the multiqueue API
   - [arm] Support binding event channels to different VCPUs.
   - [x86] Support > 512 GiB in a PV guests (off by default as such a
     guest cannot be migrated with the current toolstack).
   - [x86] PMU support for PV dom0 (limited support for using perf with
     Xen and other guests)"

* tag 'for-linus-4.3-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: (33 commits)
  xen: switch extra memory accounting to use pfns
  xen: limit memory to architectural maximum
  xen: avoid another early crash of memory limited dom0
  xen: avoid early crash of memory limited dom0
  arm/xen: Remove helpers which are PV specific
  xen/x86: Don't try to set PCE bit in CR4
  xen/PMU: PMU emulation code
  xen/PMU: Intercept PMU-related MSR and APIC accesses
  xen/PMU: Describe vendor-specific PMU registers
  xen/PMU: Initialization code for Xen PMU
  xen/PMU: Sysfs interface for setting Xen PMU mode
  xen: xensyms support
  xen: remove no longer needed p2m.h
  xen: allow more than 512 GB of RAM for 64 bit pv-domains
  xen: move p2m list if conflicting with e820 map
  xen: add explicit memblock_reserve() calls for special pages
  mm: provide early_memremap_ro to establish read-only mapping
  xen: check for initrd conflicting with e820 map
  xen: check pre-allocated page tables for conflict with memory map
  xen: check for kernel memory conflicting with memory layout
  ...
2015-09-08 11:46:48 -07:00
Linus Torvalds 7d9071a095 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
 "In this one:

   - d_move fixes (Eric Biederman)

   - UFS fixes (me; locking is mostly sane now, a bunch of bugs in error
     handling ought to be fixed)

   - switch of sb_writers to percpu rwsem (Oleg Nesterov)

   - superblock scalability (Josef Bacik and Dave Chinner)

   - swapon(2) race fix (Hugh Dickins)"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (65 commits)
  vfs: Test for and handle paths that are unreachable from their mnt_root
  dcache: Reduce the scope of i_lock in d_splice_alias
  dcache: Handle escaped paths in prepend_path
  mm: fix potential data race in SyS_swapon
  inode: don't softlockup when evicting inodes
  inode: rename i_wb_list to i_io_list
  sync: serialise per-superblock sync operations
  inode: convert inode_sb_list_lock to per-sb
  inode: add hlist_fake to avoid the inode hash lock in evict
  writeback: plug writeback at a high level
  change sb_writers to use percpu_rw_semaphore
  shift percpu_counter_destroy() into destroy_super_work()
  percpu-rwsem: kill CONFIG_PERCPU_RWSEM
  percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire()
  percpu-rwsem: introduce percpu_down_read_trylock()
  document rwsem_release() in sb_wait_write()
  fix the broken lockdep logic in __sb_start_write()
  introduce __sb_writers_{acquired,release}() helpers
  ufs_inode_get{frag,block}(): get rid of 'phys' argument
  ufs_getfrag_block(): tidy up a bit
  ...
2015-09-05 20:34:28 -07:00
Nicholas Krause 559ec2f8fd mm/hugetlb.c: make vma_has_reserves() return bool
This makes vma_has_reserves() return bool due to this particular function
only returning either one or zero as its return value.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Nicholas Krause 1ecef9ed0f mm/madvise.c: make madvise_behaviour_valid() return bool
This makes the madvise_bahaviour_valid() function return bool due to
this particular function always returning the value of either one or
zero as its return value.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Nicholas Krause ca1d6c7d9d mm/memory.c: make tlb_next_batch() return bool
This makes the tlb_next_batch() bool due to this particular function only
ever returning either one or zero as its return value.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Nicholas Krause d9e7e37b4d mm/dmapool.c: change is_page_busy() return from int to bool
This makes the function is_page_busy() return bool rather then an int now
due to this particular function's single return statement only ever
evaulating to either one or zero.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Oleg Nesterov 9943242ca4 mremap: simplify the "overlap" check in mremap_to()
Minor, but this check is overcomplicated.  Two half-intervals do NOT
overlap if END1 <= START2 || END2 <= START1, mremap_to() just needs to
negate this check.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Oleg Nesterov 1d39168697 mremap: don't do uneccesary checks if new_len == old_len
The "new_len > old_len" branch in vma_to_resize() looks very confusing.
It only covers the VM_DONTEXPAND/pgoff checks but everything below is
equally unneeded if new_len == old_len.

Change this code to return if "new_len == old_len", new_len < old_len is
not possible, otherwise the code below is wrong anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Oleg Nesterov d456fb9e52 mremap: don't do mm_populate(new_addr) on failure
move_vma() sets *locked even if move_page_tables() or ->mremap() fails,
change sys_mremap() to check "ret & ~PAGE_MASK".

I think we should simply remove the VM_LOCKED code in move_vma(), that is
why this patch doesn't change move_vma().  But this needs more cleanups.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Oleg Nesterov 5477e70a64 mm: move ->mremap() from file_operations to vm_operations_struct
vma->vm_ops->mremap() looks more natural and clean in move_vma(), and this
way ->mremap() can have more users.  Say, vdso.

While at it, s/aio_ring_remap/aio_ring_mremap/.

Note: this is the minimal change before ->mremap() finds another user in
file_operations; this method should have more arguments, and it can be
used to kill arch_remap().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Oleg Nesterov df1eab303c mremap: don't leak new_vma if f_op->mremap() fails
move_vma() can't just return if f_op->mremap() fails, we should unmap the
new vma like we do if move_page_tables() fails.  To avoid the code
duplication this patch moves the "move entries back" under the new "if
(err)" branch.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Nicholas Krause 31aafb45f4 mm/hugetlb.c: make vma_shareable() return bool
This makes vma_shareable() return bool now due to this particular function
only ever returning either one or zero as its return value.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.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>
2015-09-04 16:54:41 -07:00
Kirill A. Shutemov 1027e4436b mm: make GUP handle pfn mapping unless FOLL_GET is requested
With DAX, pfn mapping becoming more common.  The patch adjusts GUP code to
cover pfn mapping for cases when we don't need struct page to proceed.

To make it possible, let's change follow_page() code to return -EEXIST
error code if proper page table entry exists, but no corresponding struct
page.  __get_user_page() would ignore the error code and move to the next
page frame.

The immediate effect of the change is working MAP_POPULATE and mlock() on
DAX mappings.

[akpm@linux-foundation.org: fix arm64 build]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Kirill A. Shutemov d899844e9c mm: fix status code which move_pages() returns for zero page
The manpage for move_pages(2) specifies that status code for zero page is
supposed to be -EFAULT.  Currently kernel return -ENOENT in this case.

follow_page() can do it for us, if we would ask for FOLL_DUMP.  The use of
FOLL_DUMP also means that the upper layer page tables pages are no longer
allocated.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Christoph Lameter <cl@linux.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>
2015-09-04 16:54:41 -07:00
Sebastian Andrzej Siewior ce9ce6659a mm: memcontrol: bring back the VM_BUG_ON() in mem_cgroup_swapout()
Clark stumbled over a VM_BUG_ON() in -RT which was then was removed by
Johannes in commit f371763a79 ("mm: memcontrol: fix false-positive
VM_BUG_ON() on -rt").  The comment before that patch was a tiny bit better
than it is now.  While the patch claimed to fix a false-postive on -RT
this was not the case.  None of the -RT folks ACKed it and it was not a
false positive report.  That was a *real* problem.

This patch updates the comment that is improper because it refers to
"disabled preemption" as a consequence of that lock being taken.  A
spin_lock() disables preemption, true, but in this case the code relies on
the fact that the lock _also_ disables interrupts once it is acquired.
And this is the important detail (which was checked the VM_BUG_ON()) which
needs to be pointed out.  This is the hint one needs while looking at the
code.  It was explained by Johannes on the list that the per-CPU variables
are protected by local_irq_save().  The BUG_ON() was helpful.  This code
has been workarounded in -RT in the meantime.  I wouldn't mind running
into more of those if the code in question uses *special* kind of locking
since now there is no verification (in terms of lockdep or BUG_ON()) and
therefore I bring the VM_BUG_ON() check back in.

The two functions after the comment could also have a "local_irq_save()"
dance around them in order to serialize access to the per-CPU variables.
This has been avoided because the interrupts should be off.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Clark Williams <williams@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Wei Yang c0a2949883 mm/memblock: WARN_ON when nid differs from overlap region
Each memblock_region has nid to indicates the Node ID of this range.  For
the overlap case, memblock_add_range() inserts the lower part and leave
the upper part as indicated in the overlapped region.

If the nid of the new range differs from the overlapped region, the
information recorded is not correct.

This patch adds a WARN_ON when the nid of the new range differs from the
overlapped region.

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: David Rientjes <rientjes@google.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>
2015-09-04 16:54:41 -07:00
Mel Gorman d950c9477d mm: defer flush of writable TLB entries
If a PTE is unmapped and it's dirty then it was writable recently.  Due to
deferred TLB flushing, it's best to assume a writable TLB cache entry
exists.  With that assumption, the TLB must be flushed before any IO can
start or the page is freed to avoid lost writes or data corruption.  This
patch defers flushing of potentially writable TLBs as long as possible.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Mel Gorman 72b252aed5 mm: send one IPI per CPU to TLB flush all entries after unmapping pages
An IPI is sent to flush remote TLBs when a page is unmapped that was
potentially accesssed by other CPUs.  There are many circumstances where
this happens but the obvious one is kswapd reclaiming pages belonging to a
running process as kswapd and the task are likely running on separate
CPUs.

On small machines, this is not a significant problem but as machine gets
larger with more cores and more memory, the cost of these IPIs can be
high.  This patch uses a simple structure that tracks CPUs that
potentially have TLB entries for pages being unmapped.  When the unmapping
is complete, the full TLB is flushed on the assumption that a refill cost
is lower than flushing individual entries.

Architectures wishing to do this must give the following guarantee.

        If a clean page is unmapped and not immediately flushed, the
        architecture must guarantee that a write to that linear address
        from a CPU with a cached TLB entry will trap a page fault.

This is essentially what the kernel already depends on but the window is
much larger with this patch applied and is worth highlighting.  The
architecture should consider whether the cost of the full TLB flush is
higher than sending an IPI to flush each individual entry.  An additional
architecture helper called flush_tlb_local is required.  It's a trivial
wrapper with some accounting in the x86 case.

The impact of this patch depends on the workload as measuring any benefit
requires both mapped pages co-located on the LRU and memory pressure.  The
case with the biggest impact is multiple processes reading mapped pages
taken from the vm-scalability test suite.  The test case uses NR_CPU
readers of mapped files that consume 10*RAM.

Linear mapped reader on a 4-node machine with 64G RAM and 48 CPUs

                                           4.2.0-rc1          4.2.0-rc1
                                             vanilla       flushfull-v7
Ops lru-file-mmap-read-elapsed      159.62 (  0.00%)   120.68 ( 24.40%)
Ops lru-file-mmap-read-time_range    30.59 (  0.00%)     2.80 ( 90.85%)
Ops lru-file-mmap-read-time_stddv     6.70 (  0.00%)     0.64 ( 90.38%)

           4.2.0-rc1    4.2.0-rc1
             vanilla flushfull-v7
User          581.00       611.43
System       5804.93      4111.76
Elapsed       161.03       122.12

This is showing that the readers completed 24.40% faster with 29% less
system CPU time.  From vmstats, it is known that the vanilla kernel was
interrupted roughly 900K times per second during the steady phase of the
test and the patched kernel was interrupts 180K times per second.

The impact is lower on a single socket machine.

                                           4.2.0-rc1          4.2.0-rc1
                                             vanilla       flushfull-v7
Ops lru-file-mmap-read-elapsed       25.33 (  0.00%)    20.38 ( 19.54%)
Ops lru-file-mmap-read-time_range     0.91 (  0.00%)     1.44 (-58.24%)
Ops lru-file-mmap-read-time_stddv     0.28 (  0.00%)     0.47 (-65.34%)

           4.2.0-rc1    4.2.0-rc1
             vanilla flushfull-v7
User           58.09        57.64
System        111.82        76.56
Elapsed        27.29        22.55

It's still a noticeable improvement with vmstat showing interrupts went
from roughly 500K per second to 45K per second.

The patch will have no impact on workloads with no memory pressure or have
relatively few mapped pages.  It will have an unpredictable impact on the
workload running on the CPU being flushed as it'll depend on how many TLB
entries need to be refilled and how long that takes.  Worst case, the TLB
will be completely cleared of active entries when the target PFNs were not
resident at all.

[sasha.levin@oracle.com: trace tlb flush after disabling preemption in try_to_unmap_flush]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Andrea Arcangeli 230c92a879 userfaultfd: propagate the full address in THP faults
The THP faults were not propagating the original fault address.  The
latest version of the API with uffd.arg.pagefault.address is supposed to
propagate the full address through THP faults.

This was not a kernel crashing bug and it wouldn't risk to corrupt user
memory, but it would cause a SIGBUS failure because the wrong page was
being copied.

For various reasons this wasn't easily reproducible in the qemu workload,
but the strestest exposed the problem immediately.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00