Message-ID: <51638311.8030707@jp.fujitsu.com>
Date: Tue, 09 Apr 2013 11:55:13 +0900
From: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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To: Li Zefan <lizefan@huawei.com>
CC: Andrew Morton <akpm@linux-foundation.org>, Tejun Heo <tj@kernel.org>,
        Glauber Costa <glommer@parallels.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        LKML <linux-kernel@vger.kernel.org>, Cgroups <cgroups@vger.kernel.org>,
        linux-mm@kvack.org
Subject: Re: [PATCH 07/12] memcg: use css_get/put when charging/uncharging
 kmem
References: <5162648B.9070802@huawei.com> <516264FB.7030306@huawei.com>
In-Reply-To: <516264FB.7030306@huawei.com>
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(2013/04/08 15:34), Li Zefan wrote:
> Use css_get/put instead of mem_cgroup_get/put.
> 
> We can't do a simple replacement, because here mem_cgroup_put()
> is called during mem_cgroup_css_free(), while mem_cgroup_css_free()
> won't be called until css refcnt goes down to 0.
> 
> Instead we increment css refcnt in mem_cgroup_css_offline(), and
> then check if there's still kmem charges. If not, css refcnt will
> be decremented immediately, otherwise the refcnt won't be decremented
> when kmem charges goes down to 0.
> 
> v2:
> - added wmb() in kmem_cgroup_css_offline(), pointed out by Michal
> - revised comments as suggested by Michal
> - fixed to check if kmem is activated in kmem_cgroup_css_offline()
> 
> Signed-off-by: Li Zefan <lizefan@huawei.com>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>


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