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Date: Tue, 19 Jun 2012 09:09:47 +0900
From: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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To: Michal Hocko <mhocko@suse.cz>
CC: linux-mm <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        cgroups@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 1/2] memcg: remove -EINTR at rmdir()
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(2012/06/18 22:30), Michal Hocko wrote:
> On Mon 18-06-12 20:57:23, KAMEZAWA Hiroyuki wrote:
>> 2 follow-up patches for "memcg: move charges to root cgroup if use_hierarchy=0",
>> developped/tested onto memcg-devel tree. Maybe no HUNK with -next and -mm....
>> -Kame
>> ==
>> memcg: remove -EINTR at rmdir()
>>
>> By commit "memcg: move charges to root cgroup if use_hierarchy=0",
>> no memory reclaiming will occur at removing memory cgroup.
> 
> OK, so the there are only 2 reasons why move_parent could fail in this
> path. 1) it races with somebody else who is uncharging or moving the
> charge and 2) THP split.
> 1) works for us and 2) doens't seem to be serious enough to expect that
> it would stall rmdir on the group for unbound amount of time so the
> change is safe (can we make this into the changelog please?).
> 

Yes. But the failure of move_parent() (-EBUSY) will be retried.

Remaining problems are
 - attaching task while pre_destroy() is called.
 - creating child cgroup while pre_destroy() is called.

I think I need to make a patch for cgroup layer as I previously posted.
I'd like to try again.

Thanks,
-Kame