linux-kernel - [PATCH] memcg: mark mem_cgroup_page

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Message-Id: <1289334118-4448-1-git-send-email-gthelen@google.com>
Date:	Tue,  9 Nov 2010 12:21:58 -0800
From:	Greg Thelen <gthelen@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
	Johannes Weiner <hannes@...xchg.org>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Minchan Kim <minchan.kim@...il.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Greg Thelen <gthelen@...gle.com>
Subject: [PATCH] memcg: mark mem_cgroup_page_stat() underflow unlikely

Add unlikely() to indicate that underflow of per-cpu counter
sum is not expected.

The underflow is already handled, but should have been
marked unlikely.

Reported-by: Wu Fengguang <fengguang.wu@...el.com>
Signed-off-by: Greg Thelen <gthelen@...gle.com>
---
 mm/memcontrol.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ed070d0..e8fbade 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1393,7 +1393,7 @@ unsigned long mem_cgroup_page_stat(struct mem_cgroup *mem,
 	 * value.  This function returns an unsigned value, so round it up to
 	 * zero to avoid returning a very large value.
 	 */
-	if (value < 0)
+	if (unlikely(value < 0))
 		value = 0;
 
 	put_online_cpus();
-- 
1.7.3.1

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