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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2016-10-07 16:58:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-07 18:46:27 -0700
commit8496afaba93ece80a83cbd096f0675a1020ddfc4 (patch)
tree825d05640f386d2a773db46c4b449373b9422292
parent7ebffa45551fe7db86a2b32bf586f124ef484e6e (diff)
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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@kernel.org Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/sched.h1
-rw-r--r--mm/oom_kill.c15
2 files changed, 3 insertions, 13 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7543a476178b..b48cd32be445 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -525,7 +525,6 @@ static inline int get_dumpable(struct mm_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 --git a/mm/oom_kill.c b/mm/oom_kill.c
index 87fad956c96b..45097f5a8f30 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -578,20 +578,11 @@ static void oom_reap_task(struct task_struct *tsk)
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: