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Date: Fri, 9 Dec 2011 12:37:23 -0200
From: Glauber Costa <glommer@parallels.com>
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To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: <linux-kernel@vger.kernel.org>, <lizf@cn.fujitsu.com>,
        <ebiederm@xmission.com>, <davem@davemloft.net>, <gthelen@google.com>,
        <netdev@vger.kernel.org>, <linux-mm@kvack.org>, <kirill@shutemov.name>,
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        <cgroups@vger.kernel.org>, <hannes@cmpxchg.org>, <mhocko@suse.cz>,
        Paul Menage <paul@paulmenage.org>
Subject: Re: [PATCH v8 1/9] Basic kernel memory functionality for the Memory
 Controller
References: <1323120903-2831-1-git-send-email-glommer@parallels.com> <1323120903-2831-2-git-send-email-glommer@parallels.com> <20111209102113.cdb85da8.kamezawa.hiroyu@jp.fujitsu.com>
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On 12/08/2011 11:21 PM, KAMEZAWA Hiroyuki wrote:
> Hm, why you check val != parent->kmem_independent_accounting ?
>
> 	if (parent&&  parent->use_hierarchy)
> 		return -EINVAL;
> ?
>
> BTW, you didn't check this cgroup has children or not.
> I think
>
> 	if (this_cgroup->use_hierarchy&&
>               !list_empty(this_cgroup->childlen))
> 		return -EINVAL;

How about this?

         val = !!val;

         /*
          * This follows the same hierarchy restrictions than
          * mem_cgroup_hierarchy_write()
          */
         if (!parent || !parent->use_hierarchy) {
                 if (list_empty(&cgroup->children))
                         memcg->kmem_independent_accounting = val;
                 else
                         return -EBUSY;
         }
         else
                 return -EINVAL;

         return 0;