linux-kernel - [PATCH] memcg: don't do cleanup manually if mem_cgroup_css

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Message-ID: <515A8A40.6020406@huawei.com>
Date:	Tue, 2 Apr 2013 15:35:28 +0800
From:	Li Zefan <lizefan@...wei.com>
To:	Michal Hocko <mhocko@...e.cz>
CC:	Glauber Costa <glommer@...allels.com>,
	Johannes Weiner <hannes@...xchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Cgroups <cgroups@...r.kernel.org>, <linux-mm@...ck.org>
Subject: [PATCH] memcg: don't do cleanup manually if mem_cgroup_css_online()
 fails

If memcg_init_kmem() returns -errno when a memcg is being created,
mem_cgroup_css_online() will decrement memcg and its parent's refcnt,
(but strangely there's no mem_cgroup_put() for mem_cgroup_get() called
in memcg_propagate_kmem()).

But then cgroup core will call mem_cgroup_css_free() to do cleanup...

Signed-off-by: Li Zefan <lizefan@...wei.com>
---
 mm/memcontrol.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e80504e..e927fc6 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6247,16 +6247,7 @@ mem_cgroup_css_online(struct cgroup *cont)
 
 	error = memcg_init_kmem(memcg, &mem_cgroup_subsys);
 	mutex_unlock(&memcg_create_mutex);
-	if (error) {
-		/*
-		 * We call put now because our (and parent's) refcnts
-		 * are already in place. mem_cgroup_put() will internally
-		 * call __mem_cgroup_free, so return directly
-		 */
-		mem_cgroup_put(memcg);
-		if (parent->use_hierarchy)
-			mem_cgroup_put(parent);
-	}
+
 	return error;
 }
 
-- 
1.8.0.2

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