linux.git/mm/compaction.c, branch v4.11

sched/headers: Prepare to move signal wakeup & sigpending methods from into

2017-03-02T07:42:32+00:00

Fix up affected files that include this signal functionality via sched.h.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

mm/migration: make isolate_movable_page() return int type

2017-02-25T01:46:55+00:00

Patch series "HWPOISON: soft offlining for non-lru movable page", v6.

After Minchan's commit bda807d44454 ("mm: migrate: support non-lru
movable page migration"), some type of non-lru page like zsmalloc and
virtio-balloon page also support migration.

Therefore, we can:

1) soft offlining no-lru movable pages, which means when memory
   corrected errors occur on a non-lru movable page, we can stop to use
   it by migrating data onto another page and disable the original
   (maybe half-broken) one.

2) enable memory hotplug for non-lru movable pages, i.e. we may offline
   blocks, which include such pages, by using non-lru page migration.

This patchset is heavily dependent on non-lru movable page migration.

This patch (of 4):

Change the return type of isolate_movable_page() from bool to int.  It
will return 0 when isolate movable page successfully, and return -EBUSY
when it isolates failed.

There is no functional change within this patch but prepare for later
patch.

[xieyisheng1@huawei.com: v6]
  Link: http://lkml.kernel.org/r/1486108770-630-2-git-send-email-xieyisheng1@huawei.com
Link: http://lkml.kernel.org/r/1485867981-16037-2-git-send-email-ysxie@foxmail.com
Signed-off-by: Yisheng Xie 
Suggested-by: Michal Hocko 
Acked-by: Minchan Kim 
Cc: Andi Kleen 
Cc: Hanjun Guo 
Cc: Johannes Weiner 
Cc: Joonsoo Kim 
Cc: Mel Gorman 
Cc: Naoya Horiguchi 
Cc: Reza Arbab 
Cc: Taku Izumi 
Cc: Vitaly Kuznetsov 
Cc: Vlastimil Babka 
Cc: Xishi Qiu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm,compaction: serialize waitqueue_active() checks

2017-02-23T00:41:29+00:00

Without a memory barrier, the following race can occur with a high-order
allocation:

wakeup_kcompactd(order == 1)  		     kcompactd()
  [L] waitqueue_active(kcompactd_wait)
						[S] prepare_to_wait_event(kcompactd_wait)
						[L] (kcompactd_max_order == 0)
  [S] kcompactd_max_order = order;		      schedule()

Where the waitqueue_active() check is speculatively re-ordered to before
setting the actual condition (max_order), not seeing the threads that's
going to block; making us miss a wakeup.  There are a couple of options
to fix this, including calling wq_has_sleepers() which adds a full
barrier, or unconditionally doing the wake_up_interruptible() and
serialize on the q->lock.  However, to make use of the control
dependency, we just need to add L->L guarantees.

While this bug is theoretical, there have been other offenders of the
lockless waitqueue_active() in the past -- this is also documented in
the call itself.

Link: http://lkml.kernel.org/r/1483975528-24342-1-git-send-email-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, compaction: add vmstats for kcompactd work

2017-02-23T00:41:29+00:00

A "compact_daemon_wake" vmstat exists that represents the number of
times kcompactd has woken up.  This doesn't represent how much work it
actually did, though.

It's useful to understand how much compaction work is being done by
kcompactd versus other methods such as direct compaction and explicitly
triggered per-node (or system) compaction.

This adds two new vmstats: "compact_daemon_migrate_scanned" and
"compact_daemon_free_scanned" to represent the number of pages kcompactd
has scanned as part of its migration scanner and freeing scanner,
respectively.

These values are still accounted for in the general
"compact_migrate_scanned" and "compact_free_scanned" for compatibility.

It could be argued that explicitly triggered compaction could also be
tracked separately, and that could be added if others find it useful.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1612071749390.69852@chino.kir.corp.google.com
Signed-off-by: David Rientjes 
Acked-by: Vlastimil Babka 
Cc: Michal Hocko 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, compaction: allow compaction for GFP_NOFS requests

2016-12-15T00:04:07+00:00

compaction has been disabled for GFP_NOFS and GFP_NOIO requests since
the direct compaction was introduced by commit 56de7263fcf3 ("mm:
compaction: direct compact when a high-order allocation fails").  The
main reason is that the migration of page cache pages might recurse back
to fs/io layer and we could potentially deadlock.  This is overly
conservative because all the anonymous memory is migrateable in the
GFP_NOFS context just fine.  This might be a large portion of the memory
in many/most workkloads.

Remove the GFP_NOFS restriction and make sure that we skip all fs pages
(those with a mapping) while isolating pages to be migrated.  We cannot
consider clean fs pages because they might need a metadata update so
only isolate pages without any mapping for nofs requests.

The effect of this patch will be probably very limited in many/most
workloads because higher order GFP_NOFS requests are quite rare,
although different configurations might lead to very different results.
David Chinner has mentioned a heavy metadata workload with 64kB block
which to quote him:

: Unfortunately, there was an era of cargo cult configuration tweaks in the
: Ceph community that has resulted in a large number of production machines
: with XFS filesystems configured this way.  And a lot of them store large
: numbers of small files and run under significant sustained memory
: pressure.
:
: I slowly working towards getting rid of these high order allocations and
: replacing them with the equivalent number of single page allocations, but
: I haven't got that (complex) change working yet.

We can do the following to simulate that workload:
$ mkfs.xfs -f -n size=64k 
$ mount  /mnt/scratch
$ time ./fs_mark  -D  10000  -S0  -n  100000  -s  0  -L  32 \
        -d  /mnt/scratch/0  -d  /mnt/scratch/1 \
        -d  /mnt/scratch/2  -d  /mnt/scratch/3 \
        -d  /mnt/scratch/4  -d  /mnt/scratch/5 \
        -d  /mnt/scratch/6  -d  /mnt/scratch/7 \
        -d  /mnt/scratch/8  -d  /mnt/scratch/9 \
        -d  /mnt/scratch/10  -d  /mnt/scratch/11 \
        -d  /mnt/scratch/12  -d  /mnt/scratch/13 \
        -d  /mnt/scratch/14  -d  /mnt/scratch/15

and indeed is hammers the system with many high order GFP_NOFS requests as
per a simle tracepoint during the load:
$ echo '!(gfp_flags & 0x80) && (gfp_flags &0x400000)' > $TRACE_MNT/events/kmem/mm_page_alloc/filter
I am getting
5287609 order=0
     37 order=1
1594905 order=2
3048439 order=3
6699207 order=4
  66645 order=5

My testing was done in a kvm guest so performance numbers should be
taken with a grain of salt but there seems to be a difference when the
patch is applied:

* Original kernel
FSUse%        Count         Size    Files/sec     App Overhead
     1      1600000            0       4300.1         20745838
     3      3200000            0       4239.9         23849857
     5      4800000            0       4243.4         25939543
     6      6400000            0       4248.4         19514050
     8      8000000            0       4262.1         20796169
     9      9600000            0       4257.6         21288675
    11     11200000            0       4259.7         19375120
    13     12800000            0       4220.7         22734141
    14     14400000            0       4238.5         31936458
    16     16000000            0       4231.5         23409901
    18     17600000            0       4045.3         23577700
    19     19200000            0       2783.4         58299526
    21     20800000            0       2678.2         40616302
    23     22400000            0       2693.5         83973996

and xfs complaining about memory allocation not making progress
[ 2304.372647] XFS: fs_mark(3289) possible memory allocation deadlock size 65624 in kmem_alloc (mode:0x2408240)
[ 2304.443323] XFS: fs_mark(3285) possible memory allocation deadlock size 65728 in kmem_alloc (mode:0x2408240)
[ 4796.772477] XFS: fs_mark(3424) possible memory allocation deadlock size 46936 in kmem_alloc (mode:0x2408240)
[ 4796.775329] XFS: fs_mark(3423) possible memory allocation deadlock size 51416 in kmem_alloc (mode:0x2408240)
[ 4797.388808] XFS: fs_mark(3424) possible memory allocation deadlock size 65728 in kmem_alloc (mode:0x2408240)

* Patched kernel
FSUse%        Count         Size    Files/sec     App Overhead
     1      1600000            0       4289.1         19243934
     3      3200000            0       4241.6         32828865
     5      4800000            0       4248.7         32884693
     6      6400000            0       4314.4         19608921
     8      8000000            0       4269.9         24953292
     9      9600000            0       4270.7         33235572
    11     11200000            0       4346.4         40817101
    13     12800000            0       4285.3         29972397
    14     14400000            0       4297.2         20539765
    16     16000000            0       4219.6         18596767
    18     17600000            0       4273.8         49611187
    19     19200000            0       4300.4         27944451
    21     20800000            0       4270.6         22324585
    22     22400000            0       4317.6         22650382
    24     24000000            0       4065.2         22297964

So the dropdown at Count 19200000 didn't happen and there was only a
single warning about allocation not making progress
[ 3063.815003] XFS: fs_mark(3272) possible memory allocation deadlock size 65624 in kmem_alloc (mode:0x2408240)

This suggests that the patch has helped even though there is not all that
much of anonymous memory as the workload mostly generates fs metadata.  I
assume the success rate would be higher with more anonymous memory which
should be the case in many workloads.

[akpm@linux-foundation.org: fix comment]
Link: http://lkml.kernel.org/r/20161012114721.31853-1-mhocko@kernel.org
Signed-off-by: Michal Hocko 
Acked-by: Vlastimil Babka 
Cc: Mel Gorman 
Cc: Joonsoo Kim 
Cc: Dave Chinner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2016-12-13T04:50:02+00:00

Merge updates from Andrew Morton:

 - various misc bits

 - most of MM (quite a lot of MM material is awaiting the merge of
   linux-next dependencies)

 - kasan

 - printk updates

 - procfs updates

 - MAINTAINERS

 - /lib updates

 - checkpatch updates

* emailed patches from Andrew Morton : (123 commits)
  init: reduce rootwait polling interval time to 5ms
  binfmt_elf: use vmalloc() for allocation of vma_filesz
  checkpatch: don't emit unified-diff error for rename-only patches
  checkpatch: don't check c99 types like uint8_t under tools
  checkpatch: avoid multiple line dereferences
  checkpatch: don't check .pl files, improve absolute path commit log test
  scripts/checkpatch.pl: fix spelling
  checkpatch: don't try to get maintained status when --no-tree is given
  lib/ida: document locking requirements a bit better
  lib/rbtree.c: fix typo in comment of ____rb_erase_color
  lib/Kconfig.debug: make CONFIG_STRICT_DEVMEM depend on CONFIG_DEVMEM
  MAINTAINERS: add drm and drm/i915 irc channels
  MAINTAINERS: add "C:" for URI for chat where developers hang out
  MAINTAINERS: add drm and drm/i915 bug filing info
  MAINTAINERS: add "B:" for URI where to file bugs
  get_maintainer: look for arbitrary letter prefixes in sections
  printk: add Kconfig option to set default console loglevel
  printk/sound: handle more message headers
  printk/btrfs: handle more message headers
  printk/kdb: handle more message headers
  ...

mm, compaction: fix NR_ISOLATED_* stats for pfn based migration

2016-12-13T02:55:07+00:00

Since commit bda807d44454 ("mm: migrate: support non-lru movable page
migration") isolate_migratepages_block) can isolate !PageLRU pages which
would acct_isolated account as NR_ISOLATED_*.  Accounting these non-lru
pages NR_ISOLATED_{ANON,FILE} doesn't make any sense and it can misguide
heuristics based on those counters such as pgdat_reclaimable_pages resp.
too_many_isolated which would lead to unexpected stalls during the
direct reclaim without any good reason.  Note that
__alloc_contig_migrate_range can isolate a lot of pages at once.

On mobile devices such as 512M ram android Phone, it may use a big zram
swap.  In some cases zram(zsmalloc) uses too many non-lru but
migratedable pages, such as:

      MemTotal: 468148 kB
      Normal free:5620kB
      Free swap:4736kB
      Total swap:409596kB
      ZRAM: 164616kB(zsmalloc non-lru pages)
      active_anon:60700kB
      inactive_anon:60744kB
      active_file:34420kB
      inactive_file:37532kB

Fix this by only accounting lru pages to NR_ISOLATED_* in
isolate_migratepages_block right after they were isolated and we still
know they were on LRU.  Drop acct_isolated because it is called after
the fact and we've lost that information.  Batching per-cpu counter
doesn't make much improvement anyway.  Also make sure that we uncharge
only LRU pages when putting them back on the LRU in
putback_movable_pages resp.  when unmap_and_move migrates the page.

[mhocko@suse.com: replace acct_isolated() with direct counting]
Fixes: bda807d44454 ("mm: migrate: support non-lru movable page migration")
Link: http://lkml.kernel.org/r/20161019080240.9682-1-mhocko@kernel.org
Signed-off-by: Ming Ling 
Signed-off-by: Michal Hocko 
Acked-by: Minchan Kim 
Acked-by: Vlastimil Babka 
Cc: Mel Gorman 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/compaction: Convert to hotplug state machine

2016-12-01T23:52:37+00:00

Install the callbacks via the state machine. Should the hotplug init fail then
no threads are spawned.

Signed-off-by: Anna-Maria Gleixner 
Signed-off-by: Sebastian Andrzej Siewior 
Cc: Michal Hocko 
Cc: Mel Gorman 
Cc: linux-mm@kvack.org
Cc: rt@linutronix.de
Cc: Andrew Morton 
Cc: Vlastimil Babka 
Link: http://lkml.kernel.org/r/20161126231350.10321-15-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner

mm, compaction: restrict fragindex to costly orders

2016-10-08T01:46:29+00:00

Fragmentation index and the vm.extfrag_threshold sysctl is meant as a
heuristic to prevent excessive compaction for costly orders (i.e.  THP).
It's unlikely to make any difference for non-costly orders, especially
with the default threshold.  But we cannot afford any uncertainty for
the non-costly orders where the only alternative to successful
reclaim/compaction is OOM.  After the recent patches we are guaranteed
maximum effort without heuristics from compaction before deciding OOM,
and fragindex is the last remaining heuristic.  Therefore skip fragindex
altogether for non-costly orders.

Suggested-by: Michal Hocko 
Link: http://lkml.kernel.org/r/20160926162025.21555-5-vbabka@suse.cz
Signed-off-by: Vlastimil Babka 
Acked-by: Michal Hocko 
Cc: Mel Gorman 
Cc: Joonsoo Kim 
Cc: David Rientjes 
Cc: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, compaction: ignore fragindex from compaction_zonelist_suitable()

2016-10-08T01:46:29+00:00

The compaction_zonelist_suitable() function tries to determine if
compaction will be able to proceed after sufficient reclaim, i.e.
whether there are enough reclaimable pages to provide enough order-0
freepages for compaction.

This addition of reclaimable pages to the free pages works well for the
order-0 watermark check, but in the fragmentation index check we only
consider truly free pages.  Thus we can get fragindex value close to 0
which indicates failure do to lack of memory, and wrongly decide that
compaction won't be suitable even after reclaim.

Instead of trying to somehow adjust fragindex for reclaimable pages,
let's just skip it from compaction_zonelist_suitable().

Link: http://lkml.kernel.org/r/20160926162025.21555-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka 
Acked-by: Michal Hocko 
Cc: Mel Gorman 
Cc: Joonsoo Kim 
Cc: David Rientjes 
Cc: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds