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authorMichal Hocko <mhocko@suse.com>2016-05-20 16:57:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-20 17:58:30 -0700
commitbb8a4b7fd1266ef888b3a80aa5f266062b224ef4 (patch)
tree35f8d6d151acfd18bd3f030acf0f5e9d96cdfeec /mm/oom_kill.c
parent31e49bfda18464b9b0cfe42044d5a4be4a0ca0f3 (diff)
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mm, oom_reaper: hide oom reaped tasks from OOM killer more carefully
Commit 36324a990cf5 ("oom: clear TIF_MEMDIE after oom_reaper managed to unmap the address space") not only clears TIF_MEMDIE for oom reaped task but also set OOM_SCORE_ADJ_MIN for the target task to hide it from the oom killer. This works in simple cases but it is not sufficient for (unlikely) cases where the mm is shared between independent processes (as they do not share signal struct). If the mm had only small amount of memory which could be reaped then another task sharing the mm could be selected and that wouldn't help to move out from the oom situation. Introduce MMF_OOM_REAPED mm flag which is checked in oom_badness (same as OOM_SCORE_ADJ_MIN) and task is skipped if the flag is set. Set the flag after __oom_reap_task is done with a task. This will force the select_bad_process() to ignore all already oom reaped tasks as well as no such task is sacrificed for its parent. Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/oom_kill.c')
-rw-r--r--mm/oom_kill.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 415f7eb913fa..c0376efa79ec 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -174,8 +174,13 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
if (!p)
return 0;
+ /*
+ * Do not even consider tasks which are explicitly marked oom
+ * unkillable or have been already oom reaped.
+ */
adj = (long)p->signal->oom_score_adj;
- if (adj == OOM_SCORE_ADJ_MIN) {
+ if (adj == OOM_SCORE_ADJ_MIN ||
+ test_bit(MMF_OOM_REAPED, &p->mm->flags)) {
task_unlock(p);
return 0;
}
@@ -513,7 +518,7 @@ static bool __oom_reap_task(struct task_struct *tsk)
* This task can be safely ignored because we cannot do much more
* to release its memory.
*/
- tsk->signal->oom_score_adj = OOM_SCORE_ADJ_MIN;
+ set_bit(MMF_OOM_REAPED, &mm->flags);
out:
mmput(mm);
return ret;