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Date: Mon, 18 Jun 2012 16:26:49 +0400
From: Glauber Costa <glommer@parallels.com>
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To: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: <linux-mm@kvack.org>, Pekka Enberg <penberg@kernel.org>,
        Cristoph Lameter <cl@linux.com>, David Rientjes <rientjes@google.com>,
        <cgroups@vger.kernel.org>, <devel@openvz.org>,
        <linux-kernel@vger.kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Suleiman Souhlal <suleiman@google.com>,
        Pekka Enberg <penberg@cs.helsinki.fi>, Michal Hocko <mhocko@suse.cz>,
        Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH v4 19/25] memcg: disable kmem code when not in use.
References: <1340015298-14133-1-git-send-email-glommer@parallels.com> <1340015298-14133-20-git-send-email-glommer@parallels.com> <4FDF1D76.4060406@jp.fujitsu.com>
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>>
>>    static void drain_all_stock_async(struct mem_cgroup *memcg);
>> @@ -4344,8 +4358,13 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
>>    			 *
>>    			 * But it is not worth the trouble
>>    			 */
>> -			if (!memcg->kmem_accounted&&  val != RESOURCE_MAX)
>> +			mutex_lock(&set_limit_mutex);
>> +			if (!memcg->kmem_accounted&&  val != RESOURCE_MAX
>> +			&&  !memcg->kmem_accounted) {
> 
> I'm sorry why you check the value twice ?
> 

Hi Kame,

For no reason, it should be removed. I never noticed this because 1)
This is the kind of thing testing will never reveal, and 2), this
actually goes away in a later patch (memcg: propagate kmem limiting
information to children)

In any case, I will update my tree here.

Thanks for spotting this