The patch titled
Subject: mm: oom_kill: don't ignore oom score on exiting tasks
has been added to the -mm tree. Its filename is
mm-oom_kill-dont-ignore-oom-score-on-exiting-tasks.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-oom_kill-dont-ignore-oom-score-on-exiting-tasks.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-oom_kill-dont-ignore-oom-score-on-exiting-tasks.patch
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------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: oom_kill: don't ignore oom score on exiting tasks
Currently, oom_scan_process_thread() returns OOM_SCAN_ABORT when there is
a thread which is exiting. But it is possible that that thread is blocked
at down_read(&mm->mmap_sem) in exit_mm() called from do_exit() whereas
one of threads sharing that memory is doing a GFP_KERNEL allocation
between down_write(&mm->mmap_sem) and up_write(&mm->mmap_sem)
(e.g. mmap()).
----------
T1 T2
Calls mmap()
Calls _exit(0)
Arrives at vm_mmap_pgoff()
Arrives at do_exit()
Gets PF_EXITING via exit_signals()
Calls down_write(&mm->mmap_sem)
Calls do_mmap_pgoff()
Calls down_read(&mm->mmap_sem) from exit_mm()
Calls out of memory via a GFP_KERNEL allocation but
oom_scan_process_thread(T1) returns OOM_SCAN_ABORT
----------
down_read(&mm->mmap_sem) by T1 is waiting for up_write(&mm->mmap_sem) by
T2 while oom_scan_process_thread() by T2 is waiting for T1 to set
T1->mm = NULL. Under such situation, the OOM killer does not choose
a victim, which results in silent OOM livelock problem.
This patch changes oom_scan_process_thread() not to return OOM_SCAN_ABORT
when there is a thread which is exiting.
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Andrea Argangeli <andrea@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 3 ---
1 file changed, 3 deletions(-)
diff -puN mm/oom_kill.c~mm-oom_kill-dont-ignore-oom-score-on-exiting-tasks mm/oom_kill.c
--- a/mm/oom_kill.c~mm-oom_kill-dont-ignore-oom-score-on-exiting-tasks
+++ a/mm/oom_kill.c
@@ -292,9 +292,6 @@ enum oom_scan_t oom_scan_process_thread(
if (oom_task_origin(task))
return OOM_SCAN_SELECT;
- if (task_will_free_mem(task) && !is_sysrq_oom(oc))
- return OOM_SCAN_ABORT;
-
return OOM_SCAN_OK;
}
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
mm-memcontrol-generalize-locking-for-the-page-mem_cgroup-binding.patch
mm-workingset-define-radix-entry-eviction-mask.patch
mm-workingset-separate-shadow-unpacking-and-refault-calculation.patch
mm-workingset-eviction-buckets-for-bigmem-lowbit-machines.patch
mm-workingset-per-cgroup-cache-thrash-detection.patch
mm-migrate-do-not-touch-page-mem_cgroup-of-live-pages.patch
mm-simplify-lock_page_memcg.patch
mm-remove-unnecessary-uses-of-lock_page_memcg.patch
mm-oom_kill-dont-ignore-oom-score-on-exiting-tasks.patch
mm-migrate-consolidate-mem_cgroup_migrate-calls.patch
mm-memcontrol-drop-unnecessary-lru-locking-from-mem_cgroup_migrate.patch
mm-scale-kswapd-watermarks-in-proportion-to-memory.patch
mm-scale-kswapd-watermarks-in-proportion-to-memory-v3.patch
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