mm: oom_kill: switch test-and-clear of known TIF_MEMDIE to clear

exit_oom_victim() already knows that TIF_MEMDIE is set, and nobody else
can clear it concurrently.  Use clear_thread_flag() directly.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/oom_kill.c

@@ -435,8 +435,7 @@ void mark_oom_victim(struct task_struct *tsk)
  */
 void exit_oom_victim(void)
 {
-	if (!test_and_clear_thread_flag(TIF_MEMDIE))
-		return;
+	clear_thread_flag(TIF_MEMDIE);
 
 	down_read(&oom_sem);
 	/*