From 37de6be49f6c88f7d1306594b7aae5aeee2fa499 Mon Sep 17 00:00:00 2001
From: Sha Zhengju <handai.szj@taobao.com>
Date: Thu, 10 May 2012 13:01:45 -0700
Subject: memcg: free spare array to avoid memory leak

commit 8c7577637ca31385e92769a77e2ab5b428e8b99c upstream.

When the last event is unregistered, there is no need to keep the spare
array anymore.  So free it to avoid memory leak.

Signed-off-by: Sha Zhengju <handai.szj@taobao.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/memcontrol.c | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'mm')

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 283068f..ffb99b4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4605,6 +4605,12 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
 swap_buffers:
 	/* Swap primary and spare array */
 	thresholds->spare = thresholds->primary;
+	/* If all events are unregistered, free the spare array */
+	if (!new) {
+		kfree(thresholds->spare);
+		thresholds->spare = NULL;
+	}
+
 	rcu_assign_pointer(thresholds->primary, new);
 
 	/* To be sure that nobody uses thresholds */
-- 
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