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  1. 07 8月, 2015 1 次提交
  3. 18 7月, 2015 3 次提交
    • J
      mm/page_owner: set correct gfp_mask on page_owner · e2cfc911
      由 Joonsoo Kim 提交于 
      Currently, we set wrong gfp_mask to page_owner info in case of isolated
freepage by compaction and split page.  It causes incorrect mixed
pageblock report that we can get from '/proc/pagetypeinfo'.  This metric
is really useful to measure fragmentation effect so should be accurate.
This patch fixes it by setting correct information.

Without this patch, after kernel build workload is finished, number of
mixed pageblock is 112 among roughly 210 movable pageblocks.

But, with this fix, output shows that mixed pageblock is just 57.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e2cfc911
    • J
      mm/page_owner: fix possible access violation · f3a14ced
      由 Joonsoo Kim 提交于 
      When I tested my new patches, I found that page pointer which is used
for setting page_owner information is changed.  This is because page
pointer is used to set new migratetype in loop.  After this work, page
pointer could be out of bound.  If this wrong pointer is used for
page_owner, access violation happens.  Below is error message that I
got.

  BUG: unable to handle kernel paging request at 0000000000b00018
  IP: [<ffffffff81025f30>] save_stack_address+0x30/0x40
  PGD 1af2d067 PUD 166e0067 PMD 0
  Oops: 0002 [#1] SMP
  ...snip...
  Call Trace:
    print_context_stack+0xcf/0x100
    dump_trace+0x15f/0x320
    save_stack_trace+0x2f/0x50
    __set_page_owner+0x46/0x70
    __isolate_free_page+0x1f7/0x210
    split_free_page+0x21/0xb0
    isolate_freepages_block+0x1e2/0x410
    compaction_alloc+0x22d/0x2d0
    migrate_pages+0x289/0x8b0
    compact_zone+0x409/0x880
    compact_zone_order+0x6d/0x90
    try_to_compact_pages+0x110/0x210
    __alloc_pages_direct_compact+0x3d/0xe6
    __alloc_pages_nodemask+0x6cd/0x9a0
    alloc_pages_current+0x91/0x100
    runtest_store+0x296/0xa50
    simple_attr_write+0xbd/0xe0
    __vfs_write+0x28/0xf0
    vfs_write+0xa9/0x1b0
    SyS_write+0x46/0xb0
    system_call_fastpath+0x16/0x75

This patch fixes this error by moving up set_page_owner().
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Acked-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f3a14ced
    • M
      mm, meminit: suppress unused memory variable warning · ae026b2a
      由 Mel Gorman 提交于 
      The kbuild test robot reported the following

  tree:   git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
  head:   14a6f198
  commit: 3b242c66 x86: mm: enable deferred struct page initialisation on x86-64
  date:   3 days ago
  config: x86_64-randconfig-x006-201527 (attached as .config)
  reproduce:
    git checkout 3b242c66
    # save the attached .config to linux build tree
    make ARCH=x86_64

  All warnings (new ones prefixed by >>):

     mm/page_alloc.c: In function 'early_page_uninitialised':
  >> mm/page_alloc.c:247:6: warning: unused variable 'nid' [-Wunused-variable]
       int nid = early_pfn_to_nid(pfn);

It's due to the NODE_DATA macro ignoring the nid parameter on !NUMA
configurations.  This patch avoids the warning by not declaring nid.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Reported-by: NWu Fengguang <fengguang.wu@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ae026b2a
  5. 01 7月, 2015 12 次提交
  7. 25 6月, 2015 5 次提交
  9. 12 5月, 2015 1 次提交
    • A
      mm/net: Rename and move page fragment handling from net/ to mm/ · b63ae8ca
      由 Alexander Duyck 提交于 
      This change moves the __alloc_page_frag functionality out of the networking
stack and into the page allocation portion of mm.  The idea it so help make
this maintainable by placing it with other page allocation functions.

Since we are moving it from skbuff.c to page_alloc.c I have also renamed
the basic defines and structure from netdev_alloc_cache to page_frag_cache
to reflect that this is now part of a different kernel subsystem.

I have also added a simple __free_page_frag function which can handle
freeing the frags based on the skb->head pointer.  The model for this is
based off of __free_pages since we don't actually need to deal with all of
the cases that put_page handles.  I incorporated the virt_to_head_page call
and compound_order into the function as it actually allows for a signficant
size reduction by reducing code duplication.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      b63ae8ca
  11. 16 4月, 2015 1 次提交
  13. 15 4月, 2015 7 次提交
    • Y
      mm/page_alloc.c: clean up comment · 42ff2703
      由 Yaowei Bai 提交于 
      Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      42ff2703
    • D
      mm: remove GFP_THISNODE · 4167e9b2
      由 David Rientjes 提交于 
      NOTE: this is not about __GFP_THISNODE, this is only about GFP_THISNODE.

GFP_THISNODE is a secret combination of gfp bits that have different
behavior than expected.  It is a combination of __GFP_THISNODE,
__GFP_NORETRY, and __GFP_NOWARN and is special-cased in the page
allocator slowpath to fail without trying reclaim even though it may be
used in combination with __GFP_WAIT.

An example of the problem this creates: commit e97ca8e5 ("mm: fix
GFP_THISNODE callers and clarify") fixed up many users of GFP_THISNODE
that really just wanted __GFP_THISNODE.  The problem doesn't end there,
however, because even it was a no-op for alloc_misplaced_dst_page(),
which also sets __GFP_NORETRY and __GFP_NOWARN, and
migrate_misplaced_transhuge_page(), where __GFP_NORETRY and __GFP_NOWAIT
is set in GFP_TRANSHUGE.  Converting GFP_THISNODE to __GFP_THISNODE is a
no-op in these cases since the page allocator special-cases
__GFP_THISNODE && __GFP_NORETRY && __GFP_NOWARN.

It's time to just remove GFP_THISNODE entirely.  We leave __GFP_THISNODE
to restrict an allocation to a local node, but remove GFP_THISNODE and
its obscurity.  Instead, we require that a caller clear __GFP_WAIT if it
wants to avoid reclaim.

This allows the aforementioned functions to actually reclaim as they
should.  It also enables any future callers that want to do
__GFP_THISNODE but also __GFP_NORETRY && __GFP_NOWARN to reclaim.  The
rule is simple: if you don't want to reclaim, then don't set __GFP_WAIT.

Aside: ovs_flow_stats_update() really wants to avoid reclaim as well, so
it is unchanged.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: NPekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Pravin Shelar <pshelar@nicira.com>
Cc: Jarno Rajahalme <jrajahalme@nicira.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4167e9b2
    • K
      mm: completely remove dumping per-cpu lists from show_mem() · 761b0677
      由 Konstantin Khlebnikov 提交于 
      It seems nobody needs this.
Signed-off-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      761b0677
    • K
      mm: hide per-cpu lists in output of show_mem() · d1bfcdb8
      由 Konstantin Khlebnikov 提交于 
      This makes show_mem() much less verbose on huge machines.  Instead of huge
and almost useless dump of counters for each per-zone per-cpu lists this
patch prints the sum of these counters for each zone (free_pcp) and size
of per-cpu list for current cpu (local_pcp).

The filter flag SHOW_MEM_PERCPU_LISTS reverts to the old verbose mode.

[akpm@linux-foundation.org: update show_free_areas comment]
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d1bfcdb8
    • J
      mm/compaction: enhance compaction finish condition · 2149cdae
      由 Joonsoo Kim 提交于 
      Compaction has anti fragmentation algorithm.  It is that freepage should
be more than pageblock order to finish the compaction if we don't find any
freepage in requested migratetype buddy list.  This is for mitigating
fragmentation, but, there is a lack of migratetype consideration and it is
too excessive compared to page allocator's anti fragmentation algorithm.

Not considering migratetype would cause premature finish of compaction.
For example, if allocation request is for unmovable migratetype, freepage
with CMA migratetype doesn't help that allocation and compaction should
not be stopped.  But, current logic regards this situation as compaction
is no longer needed, so finish the compaction.

Secondly, condition is too excessive compared to page allocator's logic.
We can steal freepage from other migratetype and change pageblock
migratetype on more relaxed conditions in page allocator.  This is
designed to prevent fragmentation and we can use it here.  Imposing hard
constraint only to the compaction doesn't help much in this case since
page allocator would cause fragmentation again.

To solve these problems, this patch borrows anti fragmentation logic from
page allocator.  It will reduce premature compaction finish in some cases
and reduce excessive compaction work.

stress-highalloc test in mmtests with non movable order 7 allocation shows
considerable increase of compaction success rate.

Compaction success rate (Compaction success * 100 / Compaction stalls, %)
31.82 : 42.20

I tested it on non-reboot 5 runs stress-highalloc benchmark and found that
there is no more degradation on allocation success rate than before.  That
roughly means that this patch doesn't result in more fragmentations.

Vlastimil suggests additional idea that we only test for fallbacks when
migration scanner has scanned a whole pageblock.  It looked good for
fragmentation because chance of stealing increase due to making more free
pages in certain pageblock.  So, I tested it, but, it results in decreased
compaction success rate, roughly 38.00.  I guess the reason that if system
is low memory condition, watermark check could be failed due to not enough
order 0 free page and so, sometimes, we can't reach a fallback check
although migrate_pfn is aligned to pageblock_nr_pages.  I can insert code
to cope with this situation but it makes code more complicated so I don't
include his idea at this patch.

[akpm@linux-foundation.org: fix CONFIG_CMA=n build]
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2149cdae
    • J
      mm/page_alloc: factor out fallback freepage checking · 4eb7dce6
      由 Joonsoo Kim 提交于 
      This is preparation step to use page allocator's anti fragmentation logic
in compaction.  This patch just separates fallback freepage checking part
from fallback freepage management part.  Therefore, there is no functional
change.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4eb7dce6
    • J
      mm/cma: change fallback behaviour for CMA freepage · dc67647b
      由 Joonsoo Kim 提交于 
      Freepage with MIGRATE_CMA can be used only for MIGRATE_MOVABLE and they
should not be expanded to other migratetype buddy list to protect them
from unmovable/reclaimable allocation.  Implementing these requirements in
__rmqueue_fallback(), that is, finding largest possible block of freepage
has bad effect that high order freepage with MIGRATE_CMA are broken
continually although there are suitable order CMA freepage.  Reason is
that they are not be expanded to other migratetype buddy list and next
__rmqueue_fallback() invocation try to finds another largest block of
freepage and break it again.  So, MIGRATE_CMA fallback should be handled
separately.  This patch introduces __rmqueue_cma_fallback(), that just
wrapper of __rmqueue_smallest() and call it before __rmqueue_fallback() if
migratetype == MIGRATE_MOVABLE.

This results in unintended behaviour change that MIGRATE_CMA freepage is
always used first rather than other migratetype as movable allocation's
fallback.  But, as already mentioned above, MIGRATE_CMA can be used only
for MIGRATE_MOVABLE, so it is better to use MIGRATE_CMA freepage first as
much as possible.  Otherwise, we needlessly take up precious freepages
with other migratetype and increase chance of fragmentation.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      dc67647b
  15. 13 3月, 2015 1 次提交
    • M
      mm, oom: do not fail __GFP_NOFAIL allocation if oom killer is disabled · e009d5dc
      由 Michal Hocko 提交于 
      Tetsuo Handa has pointed out that __GFP_NOFAIL allocations might fail
after OOM killer is disabled if the allocation is performed by a kernel
thread.  This behavior was introduced from the very beginning by
7f33d49a ("mm, PM/Freezer: Disable OOM killer when tasks are frozen").
 This means that the basic contract for the allocation request is broken
and the context requesting such an allocation might blow up unexpectedly.

There are basically two ways forward.

1) move oom_killer_disable after kernel threads are frozen.  This has a
   risk that the OOM victim wouldn't be able to finish because it would
   depend on an already frozen kernel thread.  This would be really tricky
   to debug.

2) do not fail GFP_NOFAIL allocation no matter what and risk a
   potential Freezable kernel threads will loop and fail the suspend.
   Incidental allocations after kernel threads are frozen will at least
   dump a warning - if we are lucky and the serial console is still active
   of course...

This patch implements the later option because it is safer.  We would see
warning rather than allocation failures for the kernel threads which would
blow up otherwise and have a higher chances to identify __GFP_NOFAIL users
from deeper pm code.
Signed-off-by: NMichal Hocko <mhocko@suse.cz>
Acked-by: NDavid Rientjes <rientjes@gooogle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e009d5dc
  17. 01 3月, 2015 1 次提交
  19. 14 2月, 2015 1 次提交
    • A
      mm: page_alloc: add kasan hooks on alloc and free paths · b8c73fc2
      由 Andrey Ryabinin 提交于 
      Add kernel address sanitizer hooks to mark allocated page's addresses as
accessible in corresponding shadow region.  Mark freed pages as
inaccessible.
Signed-off-by: NAndrey Ryabinin <a.ryabinin@samsung.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: NAndrey Konovalov <adech.fo@gmail.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b8c73fc2
  21. 13 2月, 2015 2 次提交
  23. 12 2月, 2015 5 次提交
    • V
      mm: more aggressive page stealing for UNMOVABLE allocations · 9c0415eb
      由 Vlastimil Babka 提交于 
      When allocation falls back to stealing free pages of another migratetype,
it can decide to steal extra pages, or even the whole pageblock in order
to reduce fragmentation, which could happen if further allocation
fallbacks pick a different pageblock.  In try_to_steal_freepages(), one of
the situations where extra pages are stolen happens when we are trying to
allocate a MIGRATE_RECLAIMABLE page.

However, MIGRATE_UNMOVABLE allocations are not treated the same way,
although spreading such allocation over multiple fallback pageblocks is
arguably even worse than it is for RECLAIMABLE allocations.  To minimize
fragmentation, we should minimize the number of such fallbacks, and thus
steal as much as is possible from each fallback pageblock.

Note that in theory this might put more pressure on movable pageblocks and
cause movable allocations to steal back from unmovable pageblocks.
However, movable allocations are not as aggressive with stealing, and do
not cause permanent fragmentation, so the tradeoff is reasonable, and
evaluation seems to support the change.

This patch thus adds a check for MIGRATE_UNMOVABLE to the decision to
steal extra free pages.  When evaluating with stress-highalloc from
mmtests, this has reduced the number of MIGRATE_UNMOVABLE fallbacks to
roughly 1/6.  The number of these fallbacks stealing from MIGRATE_MOVABLE
block is reduced to 1/3.  There was no observation of growing number of
unmovable pageblocks over time, and also not of increased movable
allocation fallbacks.
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9c0415eb
    • V
      mm: always steal split buddies in fallback allocations · 3a1086fb
      由 Vlastimil Babka 提交于 
      When allocation falls back to another migratetype, it will steal a page
with highest available order, and (depending on this order and desired
migratetype), it might also steal the rest of free pages from the same
pageblock.

Given the preference of highest available order, it is likely that it will
be higher than the desired order, and result in the stolen buddy page
being split.  The remaining pages after split are currently stolen only
when the rest of the free pages are stolen.  This can however lead to
situations where for MOVABLE allocations we split e.g.  order-4 fallback
UNMOVABLE page, but steal only order-0 page.  Then on the next MOVABLE
allocation (which may be batched to fill the pcplists) we split another
order-3 or higher page, etc.  By stealing all pages that we have split, we
can avoid further stealing.

This patch therefore adjusts the page stealing so that buddy pages created
by split are always stolen.  This has effect only on MOVABLE allocations,
as RECLAIMABLE and UNMOVABLE allocations already always do that in
addition to stealing the rest of free pages from the pageblock.  The
change also allows to simplify try_to_steal_freepages() and factor out CMA
handling.

According to Mel, it has been intended since the beginning that buddy
pages after split would be stolen always, but it doesn't seem like it was
ever the case until commit 47118af0 ("mm: mmzone: MIGRATE_CMA
migration type added").  The commit has unintentionally introduced this
behavior, but was reverted by commit 0cbef29a ("mm:
__rmqueue_fallback() should respect pageblock type").  Neither included
evaluation.

My evaluation with stress-highalloc from mmtests shows about 2.5x
reduction of page stealing events for MOVABLE allocations, without
affecting the page stealing events for other allocation migratetypes.
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: NMinchan Kim <minchan@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3a1086fb
    • V
      mm: when stealing freepages, also take pages created by splitting buddy page · 99592d59
      由 Vlastimil Babka 提交于 
      When studying page stealing, I noticed some weird looking decisions in
try_to_steal_freepages().  The first I assume is a bug (Patch 1), the
following two patches were driven by evaluation.

Testing was done with stress-highalloc of mmtests, using the
mm_page_alloc_extfrag tracepoint and postprocessing to get counts of how
often page stealing occurs for individual migratetypes, and what
migratetypes are used for fallbacks.  Arguably, the worst case of page
stealing is when UNMOVABLE allocation steals from MOVABLE pageblock.
RECLAIMABLE allocation stealing from MOVABLE allocation is also not ideal,
so the goal is to minimize these two cases.

The evaluation of v2 wasn't always clear win and Joonsoo questioned the
results.  Here I used different baseline which includes RFC compaction
improvements from [1].  I found that the compaction improvements reduce
variability of stress-highalloc, so there's less noise in the data.

First, let's look at stress-highalloc configured to do sync compaction,
and how these patches reduce page stealing events during the test.  First
column is after fresh reboot, other two are reiterations of test without
reboot.  That was all accumulater over 5 re-iterations (so the benchmark
was run 5x3 times with 5 fresh restarts).

Baseline:

                                                   3.19-rc4        3.19-rc4        3.19-rc4
                                                  5-nothp-1       5-nothp-2       5-nothp-3
Page alloc extfrag event                               10264225     8702233    10244125
Extfrag fragmenting                                    10263271     8701552    10243473
Extfrag fragmenting for unmovable                         13595       17616       15960
Extfrag fragmenting unmovable placed with movable          7989       12193        8447
Extfrag fragmenting for reclaimable                         658        1840        1817
Extfrag fragmenting reclaimable placed with movable         558        1677        1679
Extfrag fragmenting for movable                        10249018     8682096    10225696

With Patch 1:
                                                   3.19-rc4        3.19-rc4        3.19-rc4
                                                  6-nothp-1       6-nothp-2       6-nothp-3
Page alloc extfrag event                               11834954     9877523     9774860
Extfrag fragmenting                                    11833993     9876880     9774245
Extfrag fragmenting for unmovable                          7342       16129       11712
Extfrag fragmenting unmovable placed with movable          4191       10547        6270
Extfrag fragmenting for reclaimable                         373        1130         923
Extfrag fragmenting reclaimable placed with movable         302         906         738
Extfrag fragmenting for movable                        11826278     9859621     9761610

With Patch 2:
                                                   3.19-rc4        3.19-rc4        3.19-rc4
                                                  7-nothp-1       7-nothp-2       7-nothp-3
Page alloc extfrag event                                4725990     3668793     3807436
Extfrag fragmenting                                     4725104     3668252     3806898
Extfrag fragmenting for unmovable                          6678        7974        7281
Extfrag fragmenting unmovable placed with movable          2051        3829        4017
Extfrag fragmenting for reclaimable                         429        1208        1278
Extfrag fragmenting reclaimable placed with movable         369         976        1034
Extfrag fragmenting for movable                         4717997     3659070     3798339

With Patch 3:
                                                   3.19-rc4        3.19-rc4        3.19-rc4
                                                  8-nothp-1       8-nothp-2       8-nothp-3
Page alloc extfrag event                                5016183     4700142     3850633
Extfrag fragmenting                                     5015325     4699613     3850072
Extfrag fragmenting for unmovable                          1312        3154        3088
Extfrag fragmenting unmovable placed with movable          1115        2777        2714
Extfrag fragmenting for reclaimable                         437        1193        1097
Extfrag fragmenting reclaimable placed with movable         330         969         879
Extfrag fragmenting for movable                         5013576     4695266     3845887

In v2 we've seen apparent regression with Patch 1 for unmovable events,
this is now gone, suggesting it was indeed noise.  Here, each patch
improves the situation for unmovable events.  Reclaimable is improved by
patch 1 and then either the same modulo noise, or perhaps sligtly worse -
a small price for unmovable improvements, IMHO.  The number of movable
allocations falling back to other migratetypes is most noisy, but it's
reduced to half at Patch 2 nevertheless.  These are least critical as
compaction can move them around.

If we look at success rates, the patches don't affect them, that didn't change.

Baseline:
                             3.19-rc4              3.19-rc4              3.19-rc4
                            5-nothp-1             5-nothp-2             5-nothp-3
Success 1 Min         49.00 (  0.00%)       42.00 ( 14.29%)       41.00 ( 16.33%)
Success 1 Mean        51.00 (  0.00%)       45.00 ( 11.76%)       42.60 ( 16.47%)
Success 1 Max         55.00 (  0.00%)       51.00 (  7.27%)       46.00 ( 16.36%)
Success 2 Min         53.00 (  0.00%)       47.00 ( 11.32%)       44.00 ( 16.98%)
Success 2 Mean        59.60 (  0.00%)       50.80 ( 14.77%)       48.20 ( 19.13%)
Success 2 Max         64.00 (  0.00%)       56.00 ( 12.50%)       52.00 ( 18.75%)
Success 3 Min         84.00 (  0.00%)       82.00 (  2.38%)       78.00 (  7.14%)
Success 3 Mean        85.60 (  0.00%)       82.80 (  3.27%)       79.40 (  7.24%)
Success 3 Max         86.00 (  0.00%)       83.00 (  3.49%)       80.00 (  6.98%)

Patch 1:
                             3.19-rc4              3.19-rc4              3.19-rc4
                            6-nothp-1             6-nothp-2             6-nothp-3
Success 1 Min         49.00 (  0.00%)       44.00 ( 10.20%)       44.00 ( 10.20%)
Success 1 Mean        51.80 (  0.00%)       46.00 ( 11.20%)       45.80 ( 11.58%)
Success 1 Max         54.00 (  0.00%)       49.00 (  9.26%)       49.00 (  9.26%)
Success 2 Min         58.00 (  0.00%)       49.00 ( 15.52%)       48.00 ( 17.24%)
Success 2 Mean        60.40 (  0.00%)       51.80 ( 14.24%)       50.80 ( 15.89%)
Success 2 Max         63.00 (  0.00%)       54.00 ( 14.29%)       55.00 ( 12.70%)
Success 3 Min         84.00 (  0.00%)       81.00 (  3.57%)       79.00 (  5.95%)
Success 3 Mean        85.00 (  0.00%)       81.60 (  4.00%)       79.80 (  6.12%)
Success 3 Max         86.00 (  0.00%)       82.00 (  4.65%)       82.00 (  4.65%)

Patch 2:

                             3.19-rc4              3.19-rc4              3.19-rc4
                            7-nothp-1             7-nothp-2             7-nothp-3
Success 1 Min         50.00 (  0.00%)       44.00 ( 12.00%)       39.00 ( 22.00%)
Success 1 Mean        52.80 (  0.00%)       45.60 ( 13.64%)       42.40 ( 19.70%)
Success 1 Max         55.00 (  0.00%)       46.00 ( 16.36%)       47.00 ( 14.55%)
Success 2 Min         52.00 (  0.00%)       48.00 (  7.69%)       45.00 ( 13.46%)
Success 2 Mean        53.40 (  0.00%)       49.80 (  6.74%)       48.80 (  8.61%)
Success 2 Max         57.00 (  0.00%)       52.00 (  8.77%)       52.00 (  8.77%)
Success 3 Min         84.00 (  0.00%)       81.00 (  3.57%)       79.00 (  5.95%)
Success 3 Mean        85.00 (  0.00%)       82.40 (  3.06%)       79.60 (  6.35%)
Success 3 Max         86.00 (  0.00%)       83.00 (  3.49%)       80.00 (  6.98%)

Patch 3:
                             3.19-rc4              3.19-rc4              3.19-rc4
                            8-nothp-1             8-nothp-2             8-nothp-3
Success 1 Min         46.00 (  0.00%)       44.00 (  4.35%)       42.00 (  8.70%)
Success 1 Mean        50.20 (  0.00%)       45.60 (  9.16%)       44.00 ( 12.35%)
Success 1 Max         52.00 (  0.00%)       47.00 (  9.62%)       47.00 (  9.62%)
Success 2 Min         53.00 (  0.00%)       49.00 (  7.55%)       48.00 (  9.43%)
Success 2 Mean        55.80 (  0.00%)       50.60 (  9.32%)       49.00 ( 12.19%)
Success 2 Max         59.00 (  0.00%)       52.00 ( 11.86%)       51.00 ( 13.56%)
Success 3 Min         84.00 (  0.00%)       80.00 (  4.76%)       79.00 (  5.95%)
Success 3 Mean        85.40 (  0.00%)       81.60 (  4.45%)       80.40 (  5.85%)
Success 3 Max         87.00 (  0.00%)       83.00 (  4.60%)       82.00 (  5.75%)

While there's no improvement here, I consider reduced fragmentation events
to be worth on its own.  Patch 2 also seems to reduce scanning for free
pages, and migrations in compaction, suggesting it has somewhat less work
to do:

Patch 1:

Compaction stalls                 4153        3959        3978
Compaction success                1523        1441        1446
Compaction failures               2630        2517        2531
Page migrate success           4600827     4943120     5104348
Page migrate failure             19763       16656       17806
Compaction pages isolated      9597640    10305617    10653541
Compaction migrate scanned    77828948    86533283    87137064
Compaction free scanned      517758295   521312840   521462251
Compaction cost                   5503        5932        6110

Patch 2:

Compaction stalls                 3800        3450        3518
Compaction success                1421        1316        1317
Compaction failures               2379        2134        2201
Page migrate success           4160421     4502708     4752148
Page migrate failure             19705       14340       14911
Compaction pages isolated      8731983     9382374     9910043
Compaction migrate scanned    98362797    96349194    98609686
Compaction free scanned      496512560   469502017   480442545
Compaction cost                   5173        5526        5811

As with v2, /proc/pagetypeinfo appears unaffected with respect to numbers
of unmovable and reclaimable pageblocks.

Configuring the benchmark to allocate like THP page fault (i.e.  no sync
compaction) gives much noisier results for iterations 2 and 3 after
reboot.  This is not so surprising given how [1] offers lower improvements
in this scenario due to less restarts after deferred compaction which
would change compaction pivot.

Baseline:
                                                   3.19-rc4        3.19-rc4        3.19-rc4
                                                    5-thp-1         5-thp-2         5-thp-3
Page alloc extfrag event                                8148965     6227815     6646741
Extfrag fragmenting                                     8147872     6227130     6646117
Extfrag fragmenting for unmovable                         10324       12942       15975
Extfrag fragmenting unmovable placed with movable          5972        8495       10907
Extfrag fragmenting for reclaimable                         601        1707        2210
Extfrag fragmenting reclaimable placed with movable         520        1570        2000
Extfrag fragmenting for movable                         8136947     6212481     6627932

Patch 1:
                                                   3.19-rc4        3.19-rc4        3.19-rc4
                                                    6-thp-1         6-thp-2         6-thp-3
Page alloc extfrag event                                8345457     7574471     7020419
Extfrag fragmenting                                     8343546     7573777     7019718
Extfrag fragmenting for unmovable                         10256       18535       30716
Extfrag fragmenting unmovable placed with movable          6893       11726       22181
Extfrag fragmenting for reclaimable                         465        1208        1023
Extfrag fragmenting reclaimable placed with movable         353         996         843
Extfrag fragmenting for movable                         8332825     7554034     6987979

Patch 2:
                                                   3.19-rc4        3.19-rc4        3.19-rc4
                                                    7-thp-1         7-thp-2         7-thp-3
Page alloc extfrag event                                3512847     3020756     2891625
Extfrag fragmenting                                     3511940     3020185     2891059
Extfrag fragmenting for unmovable                          9017        6892        6191
Extfrag fragmenting unmovable placed with movable          1524        3053        2435
Extfrag fragmenting for reclaimable                         445        1081        1160
Extfrag fragmenting reclaimable placed with movable         375         918         986
Extfrag fragmenting for movable                         3502478     3012212     2883708

Patch 3:
                                                   3.19-rc4        3.19-rc4        3.19-rc4
                                                    8-thp-1         8-thp-2         8-thp-3
Page alloc extfrag event                                3181699     3082881     2674164
Extfrag fragmenting                                     3180812     3082303     2673611
Extfrag fragmenting for unmovable                          1201        4031        4040
Extfrag fragmenting unmovable placed with movable           974        3611        3645
Extfrag fragmenting for reclaimable                         478        1165        1294
Extfrag fragmenting reclaimable placed with movable         387         985        1030
Extfrag fragmenting for movable                         3179133     3077107     2668277

The improvements for first iteration are clear, the rest is much noisier
and can appear like regression for Patch 1.  Anyway, patch 2 rectifies it.

Allocation success rates are again unaffected so there's no point in
making this e-mail any longer.

[1] http://marc.info/?l=linux-mm&m=142166196321125&w=2

This patch (of 3):

When __rmqueue_fallback() is called to allocate a page of order X, it will
find a page of order Y >= X of a fallback migratetype, which is different
from the desired migratetype.  With the help of try_to_steal_freepages(),
it may change the migratetype (to the desired one) also of:

1) all currently free pages in the pageblock containing the fallback page
2) the fallback pageblock itself
3) buddy pages created by splitting the fallback page (when Y > X)

These decisions take the order Y into account, as well as the desired
migratetype, with the goal of preventing multiple fallback allocations
that could e.g.  distribute UNMOVABLE allocations among multiple
pageblocks.

Originally, decision for 1) has implied the decision for 3).  Commit
47118af0 ("mm: mmzone: MIGRATE_CMA migration type added") changed that
(probably unintentionally) so that the buddy pages in case 3) are always
changed to the desired migratetype, except for CMA pageblocks.

Commit fef903ef ("mm/page_allo.c: restructure free-page stealing code
and fix a bug") did some refactoring and added a comment that the case of
3) is intended.  Commit 0cbef29a ("mm: __rmqueue_fallback() should
respect pageblock type") removed the comment and tried to restore the
original behavior where 1) implies 3), but due to the previous
refactoring, the result is instead that only 2) implies 3) - and the
conditions for 2) are less frequently met than conditions for 1).  This
may increase fragmentation in situations where the code decides to steal
all free pages from the pageblock (case 1)), but then gives back the buddy
pages produced by splitting.

This patch restores the original intended logic where 1) implies 3).
During testing with stress-highalloc from mmtests, this has shown to
decrease the number of events where UNMOVABLE and RECLAIMABLE allocations
steal from MOVABLE pageblocks, which can lead to permanent fragmentation.
In some cases it has increased the number of events when MOVABLE
allocations steal from UNMOVABLE or RECLAIMABLE pageblocks, but these are
fixable by sync compaction and thus less harmful.

Note that evaluation has shown that the behavior introduced by
47118af0 for buddy pages in case 3) is actually even better than the
original logic, so the following patch will introduce it properly once
again.  For stable backports of this patch it makes thus sense to only fix
versions containing 0cbef29a.

[iamjoonsoo.kim@lge.com: tracepoint fix]
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: NMinchan Kim <minchan@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: <stable@vger.kernel.org>	[3.13+ containing 0cbef29a]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      99592d59
    • M
      oom, PM: make OOM detection in the freezer path raceless · c32b3cbe
      由 Michal Hocko 提交于 
      Commit 5695be14 ("OOM, PM: OOM killed task shouldn't escape PM
suspend") has left a race window when OOM killer manages to
note_oom_kill after freeze_processes checks the counter.  The race
window is quite small and really unlikely and partial solution deemed
sufficient at the time of submission.

Tejun wasn't happy about this partial solution though and insisted on a
full solution.  That requires the full OOM and freezer's task freezing
exclusion, though.  This is done by this patch which introduces oom_sem
RW lock and turns oom_killer_disable() into a full OOM barrier.

oom_killer_disabled check is moved from the allocation path to the OOM
level and we take oom_sem for reading for both the check and the whole
OOM invocation.

oom_killer_disable() takes oom_sem for writing so it waits for all
currently running OOM killer invocations.  Then it disable all the further
OOMs by setting oom_killer_disabled and checks for any oom victims.
Victims are counted via mark_tsk_oom_victim resp.  unmark_oom_victim.  The
last victim wakes up all waiters enqueued by oom_killer_disable().
Therefore this function acts as the full OOM barrier.

The page fault path is covered now as well although it was assumed to be
safe before.  As per Tejun, "We used to have freezing points deep in file
system code which may be reacheable from page fault." so it would be
better and more robust to not rely on freezing points here.  Same applies
to the memcg OOM killer.

out_of_memory tells the caller whether the OOM was allowed to trigger and
the callers are supposed to handle the situation.  The page allocation
path simply fails the allocation same as before.  The page fault path will
retry the fault (more on that later) and Sysrq OOM trigger will simply
complain to the log.

Normally there wouldn't be any unfrozen user tasks after
try_to_freeze_tasks so the function will not block. But if there was an
OOM killer racing with try_to_freeze_tasks and the OOM victim didn't
finish yet then we have to wait for it. This should complete in a finite
time, though, because

	- the victim cannot loop in the page fault handler (it would die
	  on the way out from the exception)
	- it cannot loop in the page allocator because all the further
	  allocation would fail and __GFP_NOFAIL allocations are not
	  acceptable at this stage
	- it shouldn't be blocked on any locks held by frozen tasks
	  (try_to_freeze expects lockless context) and kernel threads and
	  work queues are not frozen yet
Signed-off-by: NMichal Hocko <mhocko@suse.cz>
Suggested-by: NTejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c32b3cbe
    • J
      mm: use correct format specifiers when printing address ranges · 8d29e18a
      由 Juergen Gross 提交于 
      Especially on 32 bit kernels memory node ranges are printed with 32 bit
wide addresses only.  Use u64 types and %llx specifiers to print full
width of addresses.
Signed-off-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8d29e18a