From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Fri, 24 Jun 2016 21:48:35 +0000 (-0700)
Subject: mm,oom_reaper: don't call mmput_async() without atomic_inc_not_zero()
X-Git-Tag: v4.7-rc5~11^2~40
X-Git-Url: http://git.cascardo.eti.br/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=491a1c65ae498dea0e39b24a46e528a78a8532ed

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

Commit e2fe14564d33 ("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.

Link: http://lkml.kernel.org/r/1464423365-5555-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index acbc432d1a52..be67df3b6569 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;
 	}