linux-kernel - [PATCH 5/9] mm: oom_kill: remove unnecessary locking in exit_oom

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Message-Id: <1430161555-6058-6-git-send-email-hannes@cmpxchg.org>
Date:	Mon, 27 Apr 2015 15:05:51 -0400
From:	Johannes Weiner <hannes@...xchg.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Michal Hocko <mhocko@...e.cz>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Dave Chinner <david@...morbit.com>,
	David Rientjes <rientjes@...gle.com>,
	Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 5/9] mm: oom_kill: remove unnecessary locking in exit_oom_victim()

Disabling the OOM killer needs to exclude allocators from entering,
not existing victims from exiting.

Right now the only waiter is suspend code, which achieves quiescence
by disabling the OOM killer.  But later on we want to add waits that
hold the lock instead to stop new victims from showing up.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
Acked-by: Michal Hocko <mhocko@...e.cz>
---
 mm/oom_kill.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 472f124..d3490b0 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -437,10 +437,8 @@ void exit_oom_victim(void)
 {
 	clear_thread_flag(TIF_MEMDIE);
 
-	down_read(&oom_sem);
 	if (!atomic_dec_return(&oom_victims))
 		wake_up_all(&oom_victims_wait);
-	up_read(&oom_sem);
 }
 
 /**
-- 
2.3.4

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