Message-ID: <4FC622B5.9080600@parallels.com>
Date: Wed, 30 May 2012 17:37:57 +0400
From: Glauber Costa <glommer@parallels.com>
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To: Frederic Weisbecker <fweisbec@gmail.com>
CC: <linux-kernel@vger.kernel.org>, <cgroups@vger.kernel.org>,
        <linux-mm@kvack.org>, <kamezawa.hiroyu@jp.fujitsu.com>,
        Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
        Greg Thelen <gthelen@google.com>,
        Suleiman Souhlal <suleiman@google.com>, Michal Hocko <mhocko@suse.cz>,
        Johannes Weiner <hannes@cmpxchg.org>, <devel@openvz.org>,
        David Rientjes <rientjes@google.com>, Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [PATCH v3 16/28] memcg: kmem controller charge/uncharge infrastructure
References: <1337951028-3427-1-git-send-email-glommer@parallels.com> <1337951028-3427-17-git-send-email-glommer@parallels.com> <20120530130416.GD25094@somewhere.redhat.com> <4FC61B4E.2060206@parallels.com> <20120530133736.GF25094@somewhere.redhat.com>
In-Reply-To: <20120530133736.GF25094@somewhere.redhat.com>
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On 05/30/2012 05:37 PM, Frederic Weisbecker wrote:
> Right. __mem_cgroup_get_kmem_cache() fetches the memcg of the owner
> and calls memcg_create_cache_enqueue() which does css_tryget(&memcg->css).
> After this tryget I think you're fine. And in-between you're safe against
> css_set removal due to rcu_read_lock().
>
> I'm less clear with __mem_cgroup_new_kmem_page() though...

That one does not get memcg->css but it does call mem_cgroup_get(), that 
does prevent against the memcg structure being freed, which I believe to 
be good enough.
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