The patch titled
Subject: oom, oom_reaper: do not enqueue task if it is on the oom_reaper_list head
has been added to the -mm tree. Its filename is
oom-oom_reaper-do-not-enqueue-task-if-it-is-on-the-oom_reaper_list-head.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/oom-oom_reaper-do-not-enqueue-task-if-it-is-on-the-oom_reaper_list-head.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/oom-oom_reaper-do-not-enqueue-task-if-it-is-on-the-oom_reaper_list-head.patch
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: oom, oom_reaper: do not enqueue task if it is on the oom_reaper_list head
bb29902a7515 ("oom, oom_reaper: protect oom_reaper_list using simpler
way") has simplified the check for tasks already enqueued for the oom
reaper by checking tsk->oom_reaper_list != NULL. This check is not
sufficient because the tsk might be the head of the queue without any
other tasks queued and then we would simply lockup looping on the same
task. Fix the condition by checking for the head as well.
Fixes: bb29902a7515 ("oom, oom_reaper: protect oom_reaper_list using simpler way")
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff -puN mm/oom_kill.c~oom-oom_reaper-do-not-enqueue-task-if-it-is-on-the-oom_reaper_list-head mm/oom_kill.c
--- a/mm/oom_kill.c~oom-oom_reaper-do-not-enqueue-task-if-it-is-on-the-oom_reaper_list-head
+++ a/mm/oom_kill.c
@@ -547,7 +547,11 @@ static int oom_reaper(void *unused)
static void wake_oom_reaper(struct task_struct *tsk)
{
- if (!oom_reaper_th || tsk->oom_reaper_list)
+ if (!oom_reaper_th)
+ return;
+
+ /* tsk is already queued? */
+ if (tsk == oom_reaper_list || tsk->oom_reaper_list)
return;
get_task_struct(tsk);
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
oom-oom_reaper-do-not-enqueue-task-if-it-is-on-the-oom_reaper_list-head.patch
mm-oom-rework-oom-detection.patch
mm-throttle-on-io-only-when-there-are-too-many-dirty-and-writeback-pages.patch
mm-use-watermak-checks-for-__gfp_repeat-high-order-allocations.patch
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