linux-kernel - Re: [PATCH 07/12] memcg: use css_get/put when charging/uncharging kmem

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Message-ID: <51638311.8030707@jp.fujitsu.com>
Date:	Tue, 09 Apr 2013 11:55:13 +0900
From:	Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Li Zefan <lizefan@...wei.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>,
	Glauber Costa <glommer@...allels.com>,
	Johannes Weiner <hannes@...xchg.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Cgroups <cgroups@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: [PATCH 07/12] memcg: use css_get/put when charging/uncharging
 kmem

(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@...wei.com>

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



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