[PATCH] mm,oom_reaper: don't call mmput_async() without atomic_inc_not_zero()

[Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>]

Commit e2fe14564d3316d1 ("oom_reaper: close race with exiting task")
reduced frequency of needlessly selecting next OOM victim, but was
calling mmput_async() when atomic_inc_not_zero() failed.

Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
 mm/oom_kill.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index dfb1ab6..0d781b8 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -478,6 +478,7 @@ static bool __oom_reap_task(struct task_struct *tsk)
 	mm = p->mm;
 	if (!atomic_inc_not_zero(&mm->mm_users)) {
 		task_unlock(p);
+		mm = NULL;
 		goto unlock_oom;
 	}
 
-- 
1.8.3.1

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