[PATCH] mm,oom: make oom_killer_disable() killable.

[Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>]

While oom_killer_disable() is called by freeze_processes() after all user
threads except the current thread are frozen, it is possible that kernel
threads invoke the OOM killer and sends SIGKILL to the current thread due
to sharing the thawed victim's memory. Therefore, checking for SIGKILL is
preferable than TIF_MEMDIE.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
 mm/oom_kill.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 6ebc0351..914451a 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -613,15 +613,11 @@ void exit_oom_victim(struct task_struct *tsk)
 bool oom_killer_disable(void)
 {
 	/*
-	 * Make sure to not race with an ongoing OOM killer
-	 * and that the current is not the victim.
+	 * Make sure to not race with an ongoing OOM killer. Check that the
+	 * current is not killed (possibly due to sharing the victim's memory).
 	 */
-	mutex_lock(&oom_lock);
-	if (test_thread_flag(TIF_MEMDIE)) {
-		mutex_unlock(&oom_lock);
+	if (mutex_lock_killable(&oom_lock))
 		return false;
-	}
-
 	oom_killer_disabled = true;
 	mutex_unlock(&oom_lock);
 
-- 
1.8.3.1

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