The patch titled
Subject: mm,oom_reaper: do not attempt to reap a task twice
has been added to the -mm tree. Its filename is
mmoom_reaper-do-not-attempt-to-reap-a-task-twice.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mmoom_reaper-do-not-attempt-to-reap-a-task-twice.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mmoom_reaper-do-not-attempt-to-reap-a-task-twice.patch
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------------------------------------------------------
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Subject: mm,oom_reaper: do not attempt to reap a task twice
"mm, oom_reaper: do not attempt to reap a task twice" tried to give the
OOM reaper one more chance to retry using MMF_OOM_NOT_REAPABLE flag. But
the usefulness of the flag is rather limited and actually never shown in
practice. If the flag is set, it means that the holder of mm->mmap_sem
cannot call up_write() due to presumably being blocked at unkillable wait
waiting for other thread's memory allocation. But since one of threads
sharing that mm will queue that mm immediately via task_will_free_mem()
shortcut (otherwise, oom_badness() will select the same mm again due to
oom_score_adj value unchanged), retrying MMF_OOM_NOT_REAPABLE mm is
unlikely helpful.
Let's always set MMF_OOM_REAPED.
Link: http://lkml.kernel.org/r/1472119394-11342-3-git-send-email-mhocko@xxxxxxxxxx
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sched.h | 1 -
mm/oom_kill.c | 15 +++------------
2 files changed, 3 insertions(+), 13 deletions(-)
diff -puN include/linux/sched.h~mmoom_reaper-do-not-attempt-to-reap-a-task-twice include/linux/sched.h
--- a/include/linux/sched.h~mmoom_reaper-do-not-attempt-to-reap-a-task-twice
+++ a/include/linux/sched.h
@@ -523,7 +523,6 @@ static inline int get_dumpable(struct mm
#define MMF_HAS_UPROBES 19 /* has uprobes */
#define MMF_RECALC_UPROBES 20 /* MMF_HAS_UPROBES can be wrong */
#define MMF_OOM_REAPED 21 /* mm has been already reaped */
-#define MMF_OOM_NOT_REAPABLE 22 /* mm couldn't be reaped */
#define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
diff -puN mm/oom_kill.c~mmoom_reaper-do-not-attempt-to-reap-a-task-twice mm/oom_kill.c
--- a/mm/oom_kill.c~mmoom_reaper-do-not-attempt-to-reap-a-task-twice
+++ a/mm/oom_kill.c
@@ -578,20 +578,11 @@ static void oom_reap_task(struct task_st
if (attempts <= MAX_OOM_REAP_RETRIES)
goto done;
+ /* Ignore this mm because somebody can't call up_write(mmap_sem). */
+ set_bit(MMF_OOM_REAPED, &mm->flags);
+
pr_info("oom_reaper: unable to reap pid:%d (%s)\n",
task_pid_nr(tsk), tsk->comm);
-
- /*
- * If we've already tried to reap this task in the past and
- * failed it probably doesn't make much sense to try yet again
- * so hide the mm from the oom killer so that it can move on
- * to another task with a different mm struct.
- */
- if (test_and_set_bit(MMF_OOM_NOT_REAPABLE, &mm->flags)) {
- pr_info("oom_reaper: giving up pid:%d (%s)\n",
- task_pid_nr(tsk), tsk->comm);
- set_bit(MMF_OOM_REAPED, &mm->flags);
- }
debug_show_all_locks();
done:
_
Patches currently in -mm which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
mmoom_reaper-reduce-find_lock_task_mm-usage.patch
mmoom_reaper-do-not-attempt-to-reap-a-task-twice.patch
mm-oom-enforce-exit_oom_victim-on-current-task.patch
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