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From: Michal Hocko <mhocko@suse.cz>
To: linux-mm@kvack.org
Cc: Li Zefan <lizefan@huawei.com>,
	Glauber Costa <glommer@parallels.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	linux-kernel@vger.kernel.org, cgroups@vger.kernel.org
Subject: [PATCH 1/2] Revert "memcg: avoid dangling reference count in creation failure."
Date: Wed,  3 Apr 2013 10:53:53 +0200	[thread overview]
Message-ID: <1364979234-16427-1-git-send-email-mhocko@suse.cz> (raw)
In-Reply-To: <20130403085056.GD14384@dhcp22.suse.cz>

This reverts commit e4715f01be697a3730c78f8ffffb595591d6a88c

mem_cgroup_put is hierarchy aware so mem_cgroup_put(memcg) already drops
an additional reference from all parents so the additional
mem_cgrroup_put(parent) potentially causes use-after-free.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
---
 mm/memcontrol.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f608546..6de6d70 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6424,8 +6424,6 @@ mem_cgroup_css_online(struct cgroup *cont)
 		 * call __mem_cgroup_free, so return directly
 		 */
 		mem_cgroup_put(memcg);
-		if (parent->use_hierarchy)
-			mem_cgroup_put(parent);
 	}
 	return error;
 }
-- 
1.7.10.4

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  reply	other threads:[~2013-04-03  8:54 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-02  7:35 [PATCH] memcg: don't do cleanup manually if mem_cgroup_css_online() fails Li Zefan
2013-04-02  8:03 ` Li Zefan
2013-04-02  8:07   ` Glauber Costa
2013-04-02  8:34     ` Li Zefan
2013-04-02  8:42       ` Glauber Costa
2013-04-02  8:43 ` Glauber Costa
2013-04-02 12:16 ` Michal Hocko
2013-04-02 12:22   ` Glauber Costa
2013-04-02 13:32     ` Michal Hocko
2013-04-02 13:36       ` Glauber Costa
2013-04-03  3:43       ` Li Zefan
2013-04-02 14:16   ` Michal Hocko
2013-04-02 14:20     ` Glauber Costa
2013-04-02 14:28       ` Michal Hocko
2013-04-02 14:33         ` Glauber Costa
2013-04-02 15:04           ` [PATCH -v2] " Michal Hocko
2013-04-03  3:49             ` Li Zefan
2013-04-03  7:43               ` Michal Hocko
2013-04-03  7:49                 ` Li Zefan
2013-04-03  8:18                   ` Michal Hocko
2013-04-03  8:30                     ` Glauber Costa
2013-04-03  8:37                     ` Li Zefan
2013-04-03  8:50                       ` Michal Hocko
2013-04-03  8:53                         ` Michal Hocko [this message]
2013-04-03  8:53                           ` [PATCH 2/2] memcg, kmem: clean up reference count handling on the error path Michal Hocko
2013-04-03  9:48                             ` Michal Hocko
2013-04-03  8:08             ` [PATCH -v2] memcg: don't do cleanup manually if mem_cgroup_css_online() fails Glauber Costa

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