Commit Graph

501 Commits

Author SHA1 Message Date
Aaditya Kumar 1c7e7f6c07 mm: fix lost kswapd wakeup in kswapd_stop()
Offlining memory may block forever, waiting for kswapd() to wake up
because kswapd() does not check the event kthread->should_stop before
sleeping.

The proper pattern, from Documentation/memory-barriers.txt, is:

   ---  waker  ---
   event_indicated = 1;
   wake_up_process(event_daemon);

   ---  sleeper  ---
   for (;;) {
      set_current_state(TASK_UNINTERRUPTIBLE);
      if (event_indicated)
         break;
      schedule();
   }

   set_current_state() may be wrapped by:
      prepare_to_wait();

In the kswapd() case, event_indicated is kthread->should_stop.

  === offlining memory (waker) ===
   kswapd_stop()
      kthread_stop()
         kthread->should_stop = 1
         wake_up_process()
         wait_for_completion()

  ===  kswapd_try_to_sleep (sleeper) ===
   kswapd_try_to_sleep()
      prepare_to_wait()
           .
           .
      schedule()
           .
           .
      finish_wait()

The schedule() needs to be protected by a test of kthread->should_stop,
which is wrapped by kthread_should_stop().

Reproducer:
   Do heavy file I/O in background.
   Do a memory offline/online in a tight loop

Signed-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-17 16:21:30 -07:00
Jiang Liu d8adde17e5 memory hotplug: fix invalid memory access caused by stale kswapd pointer
kswapd_stop() is called to destroy the kswapd work thread when all memory
of a NUMA node has been offlined.  But kswapd_stop() only terminates the
work thread without resetting NODE_DATA(nid)->kswapd to NULL.  The stale
pointer will prevent kswapd_run() from creating a new work thread when
adding memory to the memory-less NUMA node again.  Eventually the stale
pointer may cause invalid memory access.

An example stack dump as below. It's reproduced with 2.6.32, but latest
kernel has the same issue.

  BUG: unable to handle kernel NULL pointer dereference at (null)
  IP: [<ffffffff81051a94>] exit_creds+0x12/0x78
  PGD 0
  Oops: 0000 [#1] SMP
  last sysfs file: /sys/devices/system/memory/memory391/state
  CPU 11
  Modules linked in: cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq microcode fuse loop dm_mod tpm_tis rtc_cmos i2c_i801 rtc_core tpm serio_raw pcspkr sg tpm_bios igb i2c_core iTCO_wdt rtc_lib mptctl iTCO_vendor_support button dca bnx2 usbhid hid uhci_hcd ehci_hcd usbcore sd_mod crc_t10dif edd ext3 mbcache jbd fan ide_pci_generic ide_core ata_generic ata_piix libata thermal processor thermal_sys hwmon mptsas mptscsih mptbase scsi_transport_sas scsi_mod
  Pid: 7949, comm: sh Not tainted 2.6.32.12-qiuxishi-5-default #92 Tecal RH2285
  RIP: 0010:exit_creds+0x12/0x78
  RSP: 0018:ffff8806044f1d78  EFLAGS: 00010202
  RAX: 0000000000000000 RBX: ffff880604f22140 RCX: 0000000000019502
  RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000000
  RBP: ffff880604f22150 R08: 0000000000000000 R09: ffffffff81a4dc10
  R10: 00000000000032a0 R11: ffff880006202500 R12: 0000000000000000
  R13: 0000000000c40000 R14: 0000000000008000 R15: 0000000000000001
  FS:  00007fbc03d066f0(0000) GS:ffff8800282e0000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
  CR2: 0000000000000000 CR3: 000000060f029000 CR4: 00000000000006e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
  Process sh (pid: 7949, threadinfo ffff8806044f0000, task ffff880603d7c600)
  Stack:
   ffff880604f22140 ffffffff8103aac5 ffff880604f22140 ffffffff8104d21e
   ffff880006202500 0000000000008000 0000000000c38000 ffffffff810bd5b1
   0000000000000000 ffff880603d7c600 00000000ffffdd29 0000000000000003
  Call Trace:
    __put_task_struct+0x5d/0x97
    kthread_stop+0x50/0x58
    offline_pages+0x324/0x3da
    memory_block_change_state+0x179/0x1db
    store_mem_state+0x9e/0xbb
    sysfs_write_file+0xd0/0x107
    vfs_write+0xad/0x169
    sys_write+0x45/0x6e
    system_call_fastpath+0x16/0x1b
  Code: ff 4d 00 0f 94 c0 84 c0 74 08 48 89 ef e8 1f fd ff ff 5b 5d 31 c0 41 5c c3 53 48 8b 87 20 06 00 00 48 89 fb 48 8b bf 18 06 00 00 <8b> 00 48 c7 83 18 06 00 00 00 00 00 00 f0 ff 0f 0f 94 c0 84 c0
  RIP  exit_creds+0x12/0x78
   RSP <ffff8806044f1d78>
  CR2: 0000000000000000

[akpm@linux-foundation.org: add pglist_data.kswapd locking comments]
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-11 16:04:41 -07:00
Hugh Dickins fa9add641b mm/memcg: apply add/del_page to lruvec
Take lruvec further: pass it instead of zone to add_page_to_lru_list() and
del_page_from_lru_list(); and pagevec_lru_move_fn() pass lruvec down to
its target functions.

This cleanup eliminates a swathe of cruft in memcontrol.c, including
mem_cgroup_lru_add_list(), mem_cgroup_lru_del_list() and
mem_cgroup_lru_move_lists() - which never actually touched the lists.

In their place, mem_cgroup_page_lruvec() to decide the lruvec, previously
a side-effect of add, and mem_cgroup_update_lru_size() to maintain the
lru_size stats.

Whilst these are simplifications in their own right, the goal is to bring
the evaluation of lruvec next to the spin_locking of the lrus, in
preparation for a future patch.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:28 -07:00
Hugh Dickins 75b00af77e mm: trivial cleanups in vmscan.c
Utter trivia in mm/vmscan.c, mostly just reducing the linecount slightly;
most exciting change being get_scan_count() calling vmscan_swappiness()
once instead of twice.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:28 -07:00
Hugh Dickins 4d7dcca213 mm/memcg: get_lru_size not get_lruvec_size
Konstantin just introduced mem_cgroup_get_lruvec_size() and
get_lruvec_size(), I'm about to add mem_cgroup_update_lru_size(): but
we're dealing with the same thing, lru_size[lru].  We ought to agree on
the naming, and I do think lru_size is the more correct: so rename his
ones to get_lru_size().

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.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>
2012-05-29 16:22:28 -07:00
Konstantin Khlebnikov f9be23d6da mm/vmscan: kill struct mem_cgroup_zone
Kill struct mem_cgroup_zone and rename shrink_mem_cgroup_zone() to
shrink_lruvec(), it always shrinks one lruvec which it takes as an
argument.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:27 -07:00
Konstantin Khlebnikov 90bdcfafdc mm/vmscan: push lruvec pointer into should_continue_reclaim()
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:27 -07:00
Konstantin Khlebnikov 90126375d8 mm/vmscan: push lruvec pointer into get_scan_count()
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov 1a93be0e7a mm/vmscan: push lruvec pointer into shrink_list()
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov c56d5c7dfe mm/vmscan: push lruvec pointer into inactive_list_is_low()
Switch mem_cgroup_inactive_anon_is_low() to lruvec pointers,
mem_cgroup_get_lruvec_size() is more effective than
mem_cgroup_zone_nr_lru_pages()

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov 074291fea8 mm/vmscan: replace zone_nr_lru_pages() with get_lruvec_size()
If memory cgroup is enabled we always use lruvecs which are embedded into
struct mem_cgroup_per_zone, so we can reach lru_size counters via
container_of().

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov 27ac81d85e mm/vmscan: push lruvec pointer into putback_inactive_pages()
As zone_reclaim_stat is now located in the lruvec, we can reach it
directly.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov 95d918fc00 mm/vmscan: remove update_isolated_counts()
update_isolated_counts() is no longer required, because lumpy-reclaim was
removed.  Insanity is over, now there is only one kind of inactive page.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov 6a18adb35c mm/vmscan: push zone pointer into shrink_page_list()
It doesn't need a pointer to the cgroup - pointer to the zone is enough.
This patch also kills the "mz" argument of page_check_references() - it is
unused after "mm: memcg: count pte references from every member of the
reclaimed hierarch"

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov 5dc35979e4 mm/vmscan: push lruvec pointer into isolate_lru_pages()
Move the mem_cgroup_zone_lruvec() call from isolate_lru_pages() into
shrink_[in]active_list().  Further patches push it to shrink_zone() step
by step.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov 9e3b2f8cd3 mm/vmscan: store "priority" in struct scan_control
In memory reclaim some function have too many arguments - "priority" is
one of them.  It can be stored in struct scan_control - we construct them
on the same level.  Instead of an open coded loop we set the initial
sc.priority, and do_try_to_free_pages() decreases it down to zero.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov 3d58ab5c97 mm/memcg: use vm_swappiness from target memory cgroup
Use vm_swappiness from memory cgroup which is triggered this memory
reclaim.  This is more reasonable and allows to kill one argument.

[akpm@linux-foundation.org: fix build (patch skew)]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:26 -07:00
Konstantin Khlebnikov bbf808ed7d mm/memcg: kill mem_cgroup_lru_del()
This patch kills mem_cgroup_lru_del(), we can use
mem_cgroup_lru_del_list() instead.  On 0-order isolation we already have
right lru list id.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:25 -07:00
Konstantin Khlebnikov f3fd4a6192 mm: remove lru type checks from __isolate_lru_page()
After patch "mm: forbid lumpy-reclaim in shrink_active_list()" we can
completely remove anon/file and active/inactive lru type filters from
__isolate_lru_page(), because isolation for 0-order reclaim always
isolates pages from right lru list.  And pages-isolation for lumpy
shrink_inactive_list() or memory-compaction anyway allowed to isolate
pages from all evictable lru lists.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:25 -07:00
Konstantin Khlebnikov 3cb9945179 mm: push lru index into shrink_[in]active_list()
Let's toss lru index through call stack to isolate_lru_pages(), this is
better than its reconstructing from individual bits.

[akpm@linux-foundation.org: fix kerneldoc, per Minchan]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:25 -07:00
Hugh Dickins 89abfab133 mm/memcg: move reclaim_stat into lruvec
With mem_cgroup_disabled() now explicit, it becomes clear that the
zone_reclaim_stat structure actually belongs in lruvec, per-zone when
memcg is disabled but per-memcg per-zone when it's enabled.

We can delete mem_cgroup_get_reclaim_stat(), and change
update_page_reclaim_stat() to update just the one set of stats, the one
which get_scan_count() will actually use.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@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>
2012-05-29 16:22:25 -07:00
Hugh Dickins c3c787e8c3 mm/memcg: scanning_global_lru means mem_cgroup_disabled
Although one has to admire the skill with which it has been concealed,
scanning_global_lru(mz) is actually just an interesting way to test
mem_cgroup_disabled().  Too many developer hours have been wasted on
confusing it with global_reclaim(): just use mem_cgroup_disabled().

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Glauber Costa <glommer@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:25 -07:00
Satoru Moriya fe35004fbf mm: avoid swapping out with swappiness==0
Sometimes we'd like to avoid swapping out anonymous memory.  In
particular, avoid swapping out pages of important process or process
groups while there is a reasonable amount of pagecache on RAM so that we
can satisfy our customers' requirements.

OTOH, we can control how aggressive the kernel will swap memory pages with
/proc/sys/vm/swappiness for global and
/sys/fs/cgroup/memory/memory.swappiness for each memcg.

But with current reclaim implementation, the kernel may swap out even if
we set swappiness=0 and there is pagecache in RAM.

This patch changes the behavior with swappiness==0.  If we set
swappiness==0, the kernel does not swap out completely (for global reclaim
until the amount of free pages and filebacked pages in a zone has been
reduced to something very very small (nr_free + nr_filebacked < high
watermark)).

Signed-off-by: Satoru Moriya <satoru.moriya@hds.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:24 -07:00
Michal Hocko e48982734e mm: consider all swapped back pages in used-once logic
Commit 6457474624 ("vmscan: detect mapped file pages used only once")
made mapped pages have another round in inactive list because they might
be just short lived and so we could consider them again next time.  This
heuristic helps to reduce pressure on the active list with a streaming
IO worklods.

This patch fixes a regression introduced by this commit for heavy shmem
based workloads because unlike Anon pages, which are excluded from this
heuristic because they are usually long lived, shmem pages are handled
as a regular page cache.

This doesn't work quite well, unfortunately, if the workload is mostly
backed by shmem (in memory database sitting on 80% of memory) with a
streaming IO in the background (backup - up to 20% of memory).  Anon
inactive list is full of (dirty) shmem pages when watermarks are hit.
Shmem pages are kept in the inactive list (they are referenced) in the
first round and it is hard to reclaim anything else so we reach lower
scanning priorities very quickly which leads to an excessive swap out.

Let's fix this by excluding all swap backed pages (they tend to be long
lived wrt.  the regular page cache anyway) from used-once heuristic and
rather activate them if they are referenced.

The customer's workload is shmem backed database (80% of RAM) and they
are measuring transactions/s with an IO in the background (20%).
Transactions touch more or less random rows in the table.  The
transaction rate fell by a factor of 3 (in the worst case) because of
commit 64574746.  This patch restores the previous numbers.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan@kernel.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org>	[2.6.34+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:23 -07:00
Ying Han 096a7cf447 mm: rename is_mlocked_vma() to mlocked_vma_newpage()
Andrew pointed out that the is_mlocked_vma() is misnamed.  A function
with name like that would expect bool return and no side-effects.

Since it is called on the fault path for new page, rename it in this
patch.

Signed-off-by: Ying Han <yinghan@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
[akpm@linux-foundation.org: s/mlock_vma_newpage/mlock_vma_newpage/, per Minchan]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:20 -07:00
Johannes Weiner c3ac9a8ade mm: memcg: count pte references from every member of the reclaimed hierarchy
The rmap walker checking page table references has historically ignored
references from VMAs that were not part of the memcg that was being
reclaimed during memcg hard limit reclaim.

When transitioning global reclaim to memcg hierarchy reclaim, I missed
that bit and now references from outside a memcg are ignored even during
global reclaim.

Reverting back to traditional behaviour - count all references during
global reclaim and only mind references of the memcg being reclaimed
during limit reclaim would be one option.

However, the more generic idea is to ignore references exactly then when
they are outside the hierarchy that is currently under reclaim; because
only then will their reclamation be of any use to help the pressure
situation.  It makes no sense to ignore references from a sibling memcg
and then evict a page that will be immediately refaulted by that sibling
which contributes to the same usage of the common ancestor under
reclaim.

The solution: make the rmap walker ignore references from VMAs that are
not part of the hierarchy that is being reclaimed.

Flat limit reclaim will stay the same, hierarchical limit reclaim will
mind the references only to pages that the hierarchy owns.  Global
reclaim, since it reclaims from all memcgs, will be fixed to regard all
references.

[akpm@linux-foundation.org: name the args in the declaration]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Konstantin Khlebnikov<khlebnikov@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.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>
2012-05-29 16:22:20 -07:00
Mel Gorman 23b9da55c5 mm: vmscan: remove reclaim_mode_t
There is little motiviation for reclaim_mode_t once RECLAIM_MODE_[A]SYNC
and lumpy reclaim have been removed.  This patch gets rid of
reclaim_mode_t as well and improves the documentation about what
reclaim/compaction is and when it is triggered.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:19 -07:00
Mel Gorman 41ac1999c3 mm: vmscan: do not stall on writeback during memory compaction
This patch stops reclaim/compaction entering sync reclaim as this was
only intended for lumpy reclaim and an oversight.  Page migration has
its own logic for stalling on writeback pages if necessary and memory
compaction is already using it.

Waiting on page writeback is bad for a number of reasons but the primary
one is that waiting on writeback to a slow device like USB can take a
considerable length of time.  Page reclaim instead uses
wait_iff_congested() to throttle if too many dirty pages are being
scanned.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:19 -07:00
Mel Gorman c53919adc0 mm: vmscan: remove lumpy reclaim
This series removes lumpy reclaim and some stalling logic that was
unintentionally being used by memory compaction.  The end result is that
stalling on dirty pages during page reclaim now depends on
wait_iff_congested().

Four kernels were compared

  3.3.0     vanilla
  3.4.0-rc2 vanilla
  3.4.0-rc2 lumpyremove-v2 is patch one from this series
  3.4.0-rc2 nosync-v2r3 is the full series

Removing lumpy reclaim saves almost 900 bytes of text whereas the full
series removes 1200 bytes.

     text     data      bss       dec     hex  filename
  6740375  1927944  2260992  10929311  a6c49f  vmlinux-3.4.0-rc2-vanilla
  6739479  1927944  2260992  10928415  a6c11f  vmlinux-3.4.0-rc2-lumpyremove-v2
  6739159  1927944  2260992  10928095  a6bfdf  vmlinux-3.4.0-rc2-nosync-v2

There are behaviour changes in the series and so tests were run with
monitoring of ftrace events.  This disrupts results so the performance
results are distorted but the new behaviour should be clearer.

fs-mark running in a threaded configuration showed little of interest as
it did not push reclaim aggressively

  FS-Mark Multi Threaded
                          3.3.0-vanilla       rc2-vanilla       lumpyremove-v2r3       nosync-v2r3
  Files/s  min           3.20 ( 0.00%)        3.20 ( 0.00%)        3.20 ( 0.00%)        3.20 ( 0.00%)
  Files/s  mean          3.20 ( 0.00%)        3.20 ( 0.00%)        3.20 ( 0.00%)        3.20 ( 0.00%)
  Files/s  stddev        0.00 ( 0.00%)        0.00 ( 0.00%)        0.00 ( 0.00%)        0.00 ( 0.00%)
  Files/s  max           3.20 ( 0.00%)        3.20 ( 0.00%)        3.20 ( 0.00%)        3.20 ( 0.00%)
  Overhead min      508667.00 ( 0.00%)   521350.00 (-2.49%)   544292.00 (-7.00%)   547168.00 (-7.57%)
  Overhead mean     551185.00 ( 0.00%)   652690.73 (-18.42%)   991208.40 (-79.83%)   570130.53 (-3.44%)
  Overhead stddev    18200.69 ( 0.00%)   331958.29 (-1723.88%)  1579579.43 (-8578.68%)     9576.81 (47.38%)
  Overhead max      576775.00 ( 0.00%)  1846634.00 (-220.17%)  6901055.00 (-1096.49%)   585675.00 (-1.54%)
  MMTests Statistics: duration
  Sys Time Running Test (seconds)             309.90    300.95    307.33    298.95
  User+Sys Time Running Test (seconds)        319.32    309.67    315.69    307.51
  Total Elapsed Time (seconds)               1187.85   1193.09   1191.98   1193.73

  MMTests Statistics: vmstat
  Page Ins                                       80532       82212       81420       79480
  Page Outs                                  111434984   111456240   111437376   111582628
  Swap Ins                                           0           0           0           0
  Swap Outs                                          0           0           0           0
  Direct pages scanned                           44881       27889       27453       34843
  Kswapd pages scanned                        25841428    25860774    25861233    25843212
  Kswapd pages reclaimed                      25841393    25860741    25861199    25843179
  Direct pages reclaimed                         44881       27889       27453       34843
  Kswapd efficiency                                99%         99%         99%         99%
  Kswapd velocity                            21754.791   21675.460   21696.029   21649.127
  Direct efficiency                               100%        100%        100%        100%
  Direct velocity                               37.783      23.375      23.031      29.188
  Percentage direct scans                           0%          0%          0%          0%

ftrace showed that there was no stalling on writeback or pages submitted
for IO from reclaim context.

postmark was similar and while it was more interesting, it also did not
push reclaim heavily.

  POSTMARK
                                       3.3.0-vanilla       rc2-vanilla  lumpyremove-v2r3       nosync-v2r3
  Transactions per second:               16.00 ( 0.00%)    20.00 (25.00%)    18.00 (12.50%)    17.00 ( 6.25%)
  Data megabytes read per second:        18.80 ( 0.00%)    24.27 (29.10%)    22.26 (18.40%)    20.54 ( 9.26%)
  Data megabytes written per second:     35.83 ( 0.00%)    46.25 (29.08%)    42.42 (18.39%)    39.14 ( 9.24%)
  Files created alone per second:        28.00 ( 0.00%)    38.00 (35.71%)    34.00 (21.43%)    30.00 ( 7.14%)
  Files create/transact per second:       8.00 ( 0.00%)    10.00 (25.00%)     9.00 (12.50%)     8.00 ( 0.00%)
  Files deleted alone per second:       556.00 ( 0.00%)  1224.00 (120.14%)  3062.00 (450.72%)  6124.00 (1001.44%)
  Files delete/transact per second:       8.00 ( 0.00%)    10.00 (25.00%)     9.00 (12.50%)     8.00 ( 0.00%)

  MMTests Statistics: duration
  Sys Time Running Test (seconds)             113.34    107.99    109.73    108.72
  User+Sys Time Running Test (seconds)        145.51    139.81    143.32    143.55
  Total Elapsed Time (seconds)               1159.16    899.23    980.17   1062.27

  MMTests Statistics: vmstat
  Page Ins                                    13710192    13729032    13727944    13760136
  Page Outs                                   43071140    42987228    42733684    42931624
  Swap Ins                                           0           0           0           0
  Swap Outs                                          0           0           0           0
  Direct pages scanned                               0           0           0           0
  Kswapd pages scanned                         9941613     9937443     9939085     9929154
  Kswapd pages reclaimed                       9940926     9936751     9938397     9928465
  Direct pages reclaimed                             0           0           0           0
  Kswapd efficiency                                99%         99%         99%         99%
  Kswapd velocity                             8576.567   11051.058   10140.164    9347.109
  Direct efficiency                               100%        100%        100%        100%
  Direct velocity                                0.000       0.000       0.000       0.000

It looks like here that the full series regresses performance but as
ftrace showed no usage of wait_iff_congested() or sync reclaim I am
assuming it's a disruption due to monitoring.  Other data such as memory
usage, page IO, swap IO all looked similar.

Running a benchmark with a plain DD showed nothing very interesting.
The full series stalled in wait_iff_congested() slightly less but stall
times on vanilla kernels were marginal.

Running a benchmark that hammered on file-backed mappings showed stalls
due to congestion but not in sync writebacks

  MICRO
                                       3.3.0-vanilla       rc2-vanilla  lumpyremove-v2r3       nosync-v2r3
  MMTests Statistics: duration
  Sys Time Running Test (seconds)             308.13    294.50    298.75    299.53
  User+Sys Time Running Test (seconds)        330.45    316.28    318.93    320.79
  Total Elapsed Time (seconds)               1814.90   1833.88   1821.14   1832.91

  MMTests Statistics: vmstat
  Page Ins                                      108712      120708       97224      110344
  Page Outs                                  155514576   156017404   155813676   156193256
  Swap Ins                                           0           0           0           0
  Swap Outs                                          0           0           0           0
  Direct pages scanned                         2599253     1550480     2512822     2414760
  Kswapd pages scanned                        69742364    71150694    68839041    69692533
  Kswapd pages reclaimed                      34824488    34773341    34796602    34799396
  Direct pages reclaimed                         53693       94750       61792       75205
  Kswapd efficiency                                49%         48%         50%         49%
  Kswapd velocity                            38427.662   38797.901   37799.972   38022.889
  Direct efficiency                                 2%          6%          2%          3%
  Direct velocity                             1432.174     845.464    1379.807    1317.446
  Percentage direct scans                           3%          2%          3%          3%
  Page writes by reclaim                             0           0           0           0
  Page writes file                                   0           0           0           0
  Page writes anon                                   0           0           0           0
  Page reclaim immediate                             0           0           0        1218
  Page rescued immediate                             0           0           0           0
  Slabs scanned                                  15360       16384       13312       16384
  Direct inode steals                                0           0           0           0
  Kswapd inode steals                             4340        4327        1630        4323

  FTrace Reclaim Statistics: congestion_wait
  Direct number congest     waited                 0          0          0          0
  Direct time   congest     waited               0ms        0ms        0ms        0ms
  Direct full   congest     waited                 0          0          0          0
  Direct number conditional waited               900        870        754        789
  Direct time   conditional waited               0ms        0ms        0ms       20ms
  Direct full   conditional waited                 0          0          0          0
  KSwapd number congest     waited              2106       2308       2116       1915
  KSwapd time   congest     waited          139924ms   157832ms   125652ms   132516ms
  KSwapd full   congest     waited              1346       1530       1202       1278
  KSwapd number conditional waited             12922      16320      10943      14670
  KSwapd time   conditional waited               0ms        0ms        0ms        0ms
  KSwapd full   conditional waited                 0          0          0          0

Reclaim statistics are not radically changed.  The stall times in kswapd
are massive but it is clear that it is due to calls to congestion_wait()
and that is almost certainly the call in balance_pgdat().  Otherwise
stalls due to dirty pages are non-existant.

I ran a benchmark that stressed high-order allocation.  This is very
artifical load but was used in the past to evaluate lumpy reclaim and
compaction.  Generally I look at allocation success rates and latency
figures.

  STRESS-HIGHALLOC
                   3.3.0-vanilla       rc2-vanilla  lumpyremove-v2r3       nosync-v2r3
  Pass 1          81.00 ( 0.00%)    28.00 (-53.00%)    24.00 (-57.00%)    28.00 (-53.00%)
  Pass 2          82.00 ( 0.00%)    39.00 (-43.00%)    38.00 (-44.00%)    43.00 (-39.00%)
  while Rested    88.00 ( 0.00%)    87.00 (-1.00%)    88.00 ( 0.00%)    88.00 ( 0.00%)

  MMTests Statistics: duration
  Sys Time Running Test (seconds)             740.93    681.42    685.14    684.87
  User+Sys Time Running Test (seconds)       2922.65   3269.52   3281.35   3279.44
  Total Elapsed Time (seconds)               1161.73   1152.49   1159.55   1161.44

  MMTests Statistics: vmstat
  Page Ins                                     4486020     2807256     2855944     2876244
  Page Outs                                    7261600     7973688     7975320     7986120
  Swap Ins                                       31694           0           0           0
  Swap Outs                                      98179           0           0           0
  Direct pages scanned                           53494       57731       34406      113015
  Kswapd pages scanned                         6271173     1287481     1278174     1219095
  Kswapd pages reclaimed                       2029240     1281025     1260708     1201583
  Direct pages reclaimed                          1468       14564       16649       92456
  Kswapd efficiency                                32%         99%         98%         98%
  Kswapd velocity                             5398.133    1117.130    1102.302    1049.641
  Direct efficiency                                 2%         25%         48%         81%
  Direct velocity                               46.047      50.092      29.672      97.306
  Percentage direct scans                           0%          4%          2%          8%
  Page writes by reclaim                       1616049           0           0           0
  Page writes file                             1517870           0           0           0
  Page writes anon                               98179           0           0           0
  Page reclaim immediate                        103778       27339        9796       17831
  Page rescued immediate                             0           0           0           0
  Slabs scanned                                1096704      986112      980992      998400
  Direct inode steals                              223      215040      216736      247881
  Kswapd inode steals                           175331       61548       68444       63066
  Kswapd skipped wait                            21991           0           1           0
  THP fault alloc                                    1         135         125         134
  THP collapse alloc                               393         311         228         236
  THP splits                                        25          13           7           8
  THP fault fallback                                 0           0           0           0
  THP collapse fail                                  3           5           7           7
  Compaction stalls                                865        1270        1422        1518
  Compaction success                               370         401         353         383
  Compaction failures                              495         869        1069        1135
  Compaction pages moved                        870155     3828868     4036106     4423626
  Compaction move failure                        26429       23865       29742       27514

Success rates are completely hosed for 3.4-rc2 which is almost certainly
due to commit fe2c2a1066 ("vmscan: reclaim at order 0 when compaction
is enabled").  I expected this would happen for kswapd and impair
allocation success rates (https://lkml.org/lkml/2012/1/25/166) but I did
not anticipate this much a difference: 80% less scanning, 37% less
reclaim by kswapd

In comparison, reclaim/compaction is not aggressive and gives up easily
which is the intended behaviour.  hugetlbfs uses __GFP_REPEAT and would
be much more aggressive about reclaim/compaction than THP allocations
are.  The stress test above is allocating like neither THP or hugetlbfs
but is much closer to THP.

Mainline is now impaired in terms of high order allocation under heavy
load although I do not know to what degree as I did not test with
__GFP_REPEAT.  Keep this in mind for bugs related to hugepage pool
resizing, THP allocation and high order atomic allocation failures from
network devices.

In terms of congestion throttling, I see the following for this test

  FTrace Reclaim Statistics: congestion_wait
  Direct number congest     waited                 3          0          0          0
  Direct time   congest     waited               0ms        0ms        0ms        0ms
  Direct full   congest     waited                 0          0          0          0
  Direct number conditional waited               957        512       1081       1075
  Direct time   conditional waited               0ms        0ms        0ms        0ms
  Direct full   conditional waited                 0          0          0          0
  KSwapd number congest     waited                36          4          3          5
  KSwapd time   congest     waited            3148ms      400ms      300ms      500ms
  KSwapd full   congest     waited                30          4          3          5
  KSwapd number conditional waited             88514        197        332        542
  KSwapd time   conditional waited            4980ms        0ms        0ms        0ms
  KSwapd full   conditional waited                49          0          0          0

The "conditional waited" times are the most interesting as this is
directly impacted by the number of dirty pages encountered during scan.
As lumpy reclaim is no longer scanning contiguous ranges, it is finding
fewer dirty pages.  This brings wait times from about 5 seconds to 0.
kswapd itself is still calling congestion_wait() so it'll still stall but
it's a lot less.

In terms of the type of IO we were doing, I see this

  FTrace Reclaim Statistics: mm_vmscan_writepage
  Direct writes anon  sync                         0          0          0          0
  Direct writes anon  async                        0          0          0          0
  Direct writes file  sync                         0          0          0          0
  Direct writes file  async                        0          0          0          0
  Direct writes mixed sync                         0          0          0          0
  Direct writes mixed async                        0          0          0          0
  KSwapd writes anon  sync                         0          0          0          0
  KSwapd writes anon  async                    91682          0          0          0
  KSwapd writes file  sync                         0          0          0          0
  KSwapd writes file  async                   822629          0          0          0
  KSwapd writes mixed sync                         0          0          0          0
  KSwapd writes mixed async                        0          0          0          0

In 3.2, kswapd was doing a bunch of async writes of pages but
reclaim/compaction was never reaching a point where it was doing sync
IO.  This does not guarantee that reclaim/compaction was not calling
wait_on_page_writeback() but I would consider it unlikely.  It indicates
that merging patches 2 and 3 to stop reclaim/compaction calling
wait_on_page_writeback() should be safe.

This patch:

Lumpy reclaim had a purpose but in the mind of some, it was to kick the
system so hard it trashed.  For others the purpose was to complicate
vmscan.c.  Over time it was giving softer shoes and a nicer attitude but
memory compaction needs to step up and replace it so this patch sends
lumpy reclaim to the farm.

The tracepoint format changes for isolating LRU pages with this patch
applied.  Furthermore reclaim/compaction can no longer queue dirty pages
in pageout() if the underlying BDI is congested.  Lumpy reclaim used
this logic and reclaim/compaction was using it in error.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:19 -07:00
Rik van Riel e709ffd616 mm: remove swap token code
The swap token code no longer fits in with the current VM model.  It
does not play well with cgroups or the better NUMA placement code in
development, since we have only one swap token globally.

It also has the potential to mess with scalability of the system, by
increasing the number of non-reclaimable pages on the active and
inactive anon LRU lists.

Last but not least, the swap token code has been broken for a year
without complaints, as reported by Konstantin Khlebnikov.  This suggests
we no longer have much use for it.

The days of sub-1G memory systems with heavy use of swap are over.  If
we ever need thrashing reducing code in the future, we will have to
implement something that does scale.

Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Bob Picco <bpicco@meloft.net>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:19 -07:00
Ying Han 904249aa68 mm: fix up the vmscan stat in vmstat
The "pgsteal" stat is confusing because it counts both direct reclaim as
well as background reclaim.  However, we have "kswapd_steal" which also
counts background reclaim value.

This patch fixes it and also makes it match the existng "pgscan_" stats.

Test:
pgsteal_kswapd_dma32 447623
pgsteal_kswapd_normal 42272677
pgsteal_kswapd_movable 0
pgsteal_direct_dma32 2801
pgsteal_direct_normal 44353270
pgsteal_direct_movable 0

Signed-off-by: Ying Han <yinghan@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-25 21:26:33 -07:00
Ying Han 41c9308812 Revert "mm: vmscan: fix misused nr_reclaimed in shrink_mem_cgroup_zone()"
This reverts commit c38446cc65.

Before the commit, the code makes senses to me but not after the commit.
The "nr_reclaimed" is the number of pages reclaimed by scanning through
the memcg's lru lists.  The "nr_to_reclaim" is the target value for the
whole function.  For example, we like to early break the reclaim if
reclaimed 32 pages under direct reclaim (not DEF_PRIORITY).

After the reverted commit, the target "nr_to_reclaim" is decremented each
time by "nr_reclaimed" but we still use it to compare the "nr_reclaimed".
It just doesn't make sense to me...

Signed-off-by: Ying Han <yinghan@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-12 13:12:12 -07:00
Rik van Riel 496b919b3b Fix potential endless loop in kswapd when compaction is not enabled
We should only test compaction_suitable if the kernel is built with
CONFIG_COMPACTION, otherwise the stub compaction_suitable function will
always return COMPACT_SKIPPED and send kswapd into an infinite loop.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-24 12:18:32 -07:00
Hugh Dickins 643ac9fc54 mm: fix testorder interaction between two kswapd patches
Adjusting cc715d99e5 "mm: vmscan: forcibly scan highmem if there are
too many buffer_heads pinning highmem" for -stable reveals that it was
slightly wrong once on top of fe2c2a1066 "vmscan: reclaim at order 0
when compaction is enabled", which specifically adds testorder for the
zone_watermark_ok_safe() test.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23 08:34:40 -07:00
Konstantin Khlebnikov 1480de0340 mm: forbid lumpy-reclaim in shrink_active_list()
Reset the reclaim mode in shrink_active_list() to RECLAIM_MODE_SINGLE |
RECLAIM_MODE_ASYNC.  (sync/async sign is used only in shrink_page_list
and does not affect shrink_active_list)

Currenly shrink_active_list() sometimes works in lumpy-reclaim mode, if
RECLAIM_MODE_LUMPYRECLAIM is left over from an earlier
shrink_inactive_list().  Meanwhile, in age_active_anon()
sc->reclaim_mode is totally zero.  So the current behavior is too
complex and confusing, and this looks like bug.

In general, shrink_active_list() populates the inactive list for the
next shrink_inactive_list().  Lumpy shring_inactive_list() isolates
pages around the chosen one from both the active and inactive lists.
So, there is no reason for lumpy isolation in shrink_active_list().

See also: https://lkml.org/lkml/2012/3/15/583

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Proposed-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:55:00 -07:00
Mel Gorman cc9a6c8776 cpuset: mm: reduce large amounts of memory barrier related damage v3
Commit c0ff7453bb ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") wins a super prize for the largest number of
memory barriers entered into fast paths for one commit.

[get|put]_mems_allowed is incredibly heavy with pairs of full memory
barriers inserted into a number of hot paths.  This was detected while
investigating at large page allocator slowdown introduced some time
after 2.6.32.  The largest portion of this overhead was shown by
oprofile to be at an mfence introduced by this commit into the page
allocator hot path.

For extra style points, the commit introduced the use of yield() in an
implementation of what looks like a spinning mutex.

This patch replaces the full memory barriers on both read and write
sides with a sequence counter with just read barriers on the fast path
side.  This is much cheaper on some architectures, including x86.  The
main bulk of the patch is the retry logic if the nodemask changes in a
manner that can cause a false failure.

While updating the nodemask, a check is made to see if a false failure
is a risk.  If it is, the sequence number gets bumped and parallel
allocators will briefly stall while the nodemask update takes place.

In a page fault test microbenchmark, oprofile samples from
__alloc_pages_nodemask went from 4.53% of all samples to 1.15%.  The
actual results were

                             3.3.0-rc3          3.3.0-rc3
                             rc3-vanilla        nobarrier-v2r1
    Clients   1 UserTime       0.07 (  0.00%)   0.08 (-14.19%)
    Clients   2 UserTime       0.07 (  0.00%)   0.07 (  2.72%)
    Clients   4 UserTime       0.08 (  0.00%)   0.07 (  3.29%)
    Clients   1 SysTime        0.70 (  0.00%)   0.65 (  6.65%)
    Clients   2 SysTime        0.85 (  0.00%)   0.82 (  3.65%)
    Clients   4 SysTime        1.41 (  0.00%)   1.41 (  0.32%)
    Clients   1 WallTime       0.77 (  0.00%)   0.74 (  4.19%)
    Clients   2 WallTime       0.47 (  0.00%)   0.45 (  3.73%)
    Clients   4 WallTime       0.38 (  0.00%)   0.37 (  1.58%)
    Clients   1 Flt/sec/cpu  497620.28 (  0.00%) 520294.53 (  4.56%)
    Clients   2 Flt/sec/cpu  414639.05 (  0.00%) 429882.01 (  3.68%)
    Clients   4 Flt/sec/cpu  257959.16 (  0.00%) 258761.48 (  0.31%)
    Clients   1 Flt/sec      495161.39 (  0.00%) 517292.87 (  4.47%)
    Clients   2 Flt/sec      820325.95 (  0.00%) 850289.77 (  3.65%)
    Clients   4 Flt/sec      1020068.93 (  0.00%) 1022674.06 (  0.26%)
    MMTests Statistics: duration
    Sys Time Running Test (seconds)             135.68    132.17
    User+Sys Time Running Test (seconds)         164.2    160.13
    Total Elapsed Time (seconds)                123.46    120.87

The overall improvement is small but the System CPU time is much
improved and roughly in correlation to what oprofile reported (these
performance figures are without profiling so skew is expected).  The
actual number of page faults is noticeably improved.

For benchmarks like kernel builds, the overall benefit is marginal but
the system CPU time is slightly reduced.

To test the actual bug the commit fixed I opened two terminals.  The
first ran within a cpuset and continually ran a small program that
faulted 100M of anonymous data.  In a second window, the nodemask of the
cpuset was continually randomised in a loop.

Without the commit, the program would fail every so often (usually
within 10 seconds) and obviously with the commit everything worked fine.
With this patch applied, it also worked fine so the fix should be
functionally equivalent.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:54:59 -07:00
Copot Alexandru c7cfa37b73 mm/vmscan.c: fix spelling error
s/noticable/noticeable/

Signed-off-by: Copot Alexandru <alex.mihai.c@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:54:59 -07:00
Hillf Danton d563c0501b vmscan: handle isolated pages with lru lock released
When shrinking inactive lru list, isolated pages are queued on locally
private list, so the lock-hold time could be reduced if pages are counted
without lock protection.

To achieve that, firstly updating reclaim stat is delayed until the
putback stage, after reacquiring the lru lock.

Secondly, operations related to vm and zone stats are now proteced with
preemption disabled as they are per-cpu operations.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:54:57 -07:00
Mel Gorman cc715d99e5 mm: vmscan: forcibly scan highmem if there are too many buffer_heads pinning highmem
Stuart Foster reported on bugzilla that copying large amounts of data
from NTFS caused an OOM kill on 32-bit X86 with 16G of memory.  Andrew
Morton correctly identified that the problem was NTFS was using 512
blocks meaning each page had 8 buffer_heads in low memory pinning it.

In the past, direct reclaim used to scan highmem even if the allocating
process did not specify __GFP_HIGHMEM but not any more.  kswapd no longer
will reclaim from zones that are above the high watermark.  The intention
in both cases was to minimise unnecessary reclaim.  The downside is on
machines with large amounts of highmem that lowmem can be fully consumed
by buffer_heads with nothing trying to free them.

The following patch is based on a suggestion by Andrew Morton to extend
the buffer_heads_over_limit case to force kswapd and direct reclaim to
scan the highmem zone regardless of the allocation request or watermarks.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=42578

[hughd@google.com: move buffer_heads_over_limit check up]
[akpm@linux-foundation.org: buffer_heads_over_limit is unlikely]
Reported-by: Stuart Foster <smf.linux@ntlworld.com>
Tested-by: Stuart Foster <smf.linux@ntlworld.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:54:57 -07:00
Rik van Riel aff622495c vmscan: only defer compaction for failed order and higher
Currently a failed order-9 (transparent hugepage) compaction can lead to
memory compaction being temporarily disabled for a memory zone.  Even if
we only need compaction for an order 2 allocation, eg.  for jumbo frames
networking.

The fix is relatively straightforward: keep track of the highest order at
which compaction is succeeding, and only defer compaction for orders at
which compaction is failing.

Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:54:56 -07:00
Rik van Riel 7be62de99a vmscan: kswapd carefully call compaction
With CONFIG_COMPACTION enabled, kswapd does not try to free contiguous
free pages, even when it is woken for a higher order request.

This could be bad for eg.  jumbo frame network allocations, which are done
from interrupt context and cannot compact memory themselves.  Higher than
before allocation failure rates in the network receive path have been
observed in kernels with compaction enabled.

Teach kswapd to defragment the memory zones in a node, but only if
required and compaction is not deferred in a zone.

[akpm@linux-foundation.org: reduce scope of zones_need_compaction]
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:54:56 -07:00
Rik van Riel fe2c2a1066 vmscan: reclaim at order 0 when compaction is enabled
When built with CONFIG_COMPACTION, kswapd should not try to free
contiguous pages, because it is not trying hard enough to have a real
chance at being successful, but still disrupts the LRU enough to break
other things.

Do not do higher order page isolation unless we really are in lumpy
reclaim mode.

Stop reclaiming pages once we have enough free pages that compaction can
deal with things, and we hit the normal order 0 watermarks used by kswapd.

Also remove a line of code that increments balanced right before exiting
the function.

Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:54:56 -07:00
Hillf Danton c38446cc65 mm: vmscan: fix misused nr_reclaimed in shrink_mem_cgroup_zone()
The value of nr_reclaimed is the number of pages reclaimed in the current
round of the loop, whereas nr_to_reclaim should be compared with the
number of pages reclaimed in all rounds.

In each round of the loop, reclaimed pages are cut off from the reclaim
goal, and the loop stops once the goal achieved.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:54:56 -07:00
Hillf Danton 6131728914 mm/vmscan.c: cleanup with s/reclaim_mode/isolate_mode/
With tons of reclaim_mode (defined as one field of struct scan_control)
already in the file, it is clearer to rename the local reclaim_mode when
setting up the isolation mode.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-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>
2012-03-21 17:54:55 -07:00
Hugh Dickins 245132643e SHM_UNLOCK: fix Unevictable pages stranded after swap
Commit cc39c6a9bb ("mm: account skipped entries to avoid looping in
find_get_pages") correctly fixed an infinite loop; but left a problem
that find_get_pages() on shmem would return 0 (appearing to callers to
mean end of tree) when it meets a run of nr_pages swap entries.

The only uses of find_get_pages() on shmem are via pagevec_lookup(),
called from invalidate_mapping_pages(), and from shmctl SHM_UNLOCK's
scan_mapping_unevictable_pages().  The first is already commented, and
not worth worrying about; but the second can leave pages on the
Unevictable list after an unusual sequence of swapping and locking.

Fix that by using shmem_find_get_pages_and_swap() (then ignoring the
swap) instead of pagevec_lookup().

But I don't want to contaminate vmscan.c with shmem internals, nor
shmem.c with LRU locking.  So move scan_mapping_unevictable_pages() into
shmem.c, renaming it shmem_unlock_mapping(); and rename
check_move_unevictable_page() to check_move_unevictable_pages(), looping
down an array of pages, oftentimes under the same lock.

Leave out the "rotate unevictable list" block: that's a leftover from
when this was used for /proc/sys/vm/scan_unevictable_pages, whose flawed
handling involved looking at pages at tail of LRU.

Was there significance to the sequence first ClearPageUnevictable, then
test page_evictable, then SetPageUnevictable here? I think not, we're
under LRU lock, and have no barriers between those.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: <stable@vger.kernel.org> [back to 3.1 but will need respins]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-23 08:38:48 -08:00
Hugh Dickins 85046579bd SHM_UNLOCK: fix long unpreemptible section
scan_mapping_unevictable_pages() is used to make SysV SHM_LOCKed pages
evictable again once the shared memory is unlocked.  It does this with
pagevec_lookup()s across the whole object (which might occupy most of
memory), and takes 300ms to unlock 7GB here.  A cond_resched() every
PAGEVEC_SIZE pages would be good.

However, KOSAKI-san points out that this is called under shmem.c's
info->lock, and it's also under shm.c's shm_lock(), both spinlocks.
There is no strong reason for that: we need to take these pages off the
unevictable list soonish, but those locks are not required for it.

So move the call to scan_mapping_unevictable_pages() from shmem.c's
unlock handling up to shm.c's unlock handling.  Remove the recently
added barrier, not needed now we have spin_unlock() before the scan.

Use get_file(), with subsequent fput(), to make sure we have a reference
to mapping throughout scan_mapping_unevictable_pages(): that's something
that was previously guaranteed by the shm_lock().

Remove shmctl's lru_add_drain_all(): we don't fault in pages at SHM_LOCK
time, and we lazily discover them to be Unevictable later, so it serves
no purpose for SHM_LOCK; and serves no purpose for SHM_UNLOCK, since
pages still on pagevec are not marked Unevictable.

The original code avoided redundant rescans by checking VM_LOCKED flag
at its level: now avoid them by checking shp's SHM_LOCKED.

The original code called scan_mapping_unevictable_pages() on a locked
area at shm_destroy() time: perhaps we once had accounting cross-checks
which required that, but not now, so skip the overhead and just let
inode eviction deal with them.

Put check_move_unevictable_page() and scan_mapping_unevictable_pages()
under CONFIG_SHMEM (with stub for the TINY case when ramfs is used),
more as comment than to save space; comment them used for SHM_UNLOCK.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-23 08:38:48 -08:00
Hugh Dickins 3f79768f23 mm: rearrange putback_inactive_pages
There is sometimes confusion between the global putback_lru_pages() in
migrate.c and the static putback_lru_pages() in vmscan.c: rename the
latter putback_inactive_pages(): it helps shrink_inactive_list() rather as
move_active_pages_to_lru() helps shrink_active_list().

Remove unused scan_control arg from putback_inactive_pages() and from
update_isolated_counts().  Move clear_active_flags() inside
update_isolated_counts().  Move NR_ISOLATED accounting up into
shrink_inactive_list() itself, so the balance is clearer.

Do the spin_lock_irq() before calling putback_inactive_pages() and
spin_unlock_irq() after return from it, so that it better matches
update_isolated_counts() and move_active_pages_to_lru().

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-12 20:13:10 -08:00
Hugh Dickins f626012db0 mm: remove isolate_pages()
The isolate_pages() level in vmscan.c offers little but indirection: merge
it into isolate_lru_pages() as the compiler does, and use the names
nr_to_scan and nr_scanned in each case.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-12 20:13:10 -08:00
Hugh Dickins 4111304dab mm: enum lru_list lru
Mostly we use "enum lru_list lru": change those few "l"s to "lru"s.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-12 20:13:10 -08:00
Hugh Dickins 2bcf887963 mm: take pagevecs off reclaim stack
Replace pagevecs in putback_lru_pages() and move_active_pages_to_lru()
by lists of pages_to_free: then apply Konstantin Khlebnikov's
free_hot_cold_page_list() to them instead of pagevec_release().

Which simplifies the flow (no need to drop and retake lock whenever
pagevec fills up) and reduces stale addresses in stack backtraces
(which often showed through the pagevecs); but more importantly,
removes another 120 bytes from the deepest stacks in page reclaim.
Although I've not recently seen an actual stack overflow here with
a vanilla kernel, move_active_pages_to_lru() has often featured in
deep backtraces.

However, free_hot_cold_page_list() does not handle compound pages
(nor need it: a Transparent HugePage would have been split by the
time it reaches the call in shrink_page_list()), but it is possible
for putback_lru_pages() or move_active_pages_to_lru() to be left
holding the last reference on a THP, so must exclude the unlikely
compound case before putting on pages_to_free.

Remove pagevec_strip(), its work now done in move_active_pages_to_lru().
The pagevec in scan_mapping_unevictable_pages() remains in mm/vmscan.c,
but that is never on the reclaim path, and cannot be replaced by a list.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-12 20:13:10 -08:00