linux-kernel - Re: [PATCH v3 4/7] memcg: remove memcg from the reclaim iterators

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Message-ID: <50EA689B.7060308@jp.fujitsu.com>
Date:	Mon, 07 Jan 2013 15:18:03 +0900
From:	Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Michal Hocko <mhocko@...e.cz>
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Johannes Weiner <hannes@...xchg.org>,
	Ying Han <yinghan@...gle.com>, Tejun Heo <htejun@...il.com>,
	Glauber Costa <glommer@...allels.com>,
	Li Zefan <lizefan@...wei.com>
Subject: Re: [PATCH v3 4/7] memcg: remove memcg from the reclaim iterators

(2013/01/04 2:54), Michal Hocko wrote:
> Now that per-node-zone-priority iterator caches memory cgroups rather
> than their css ids we have to be careful and remove them from the
> iterator when they are on the way out otherwise they might hang for
> unbounded amount of time (until the global/targeted reclaim triggers the
> zone under priority to find out the group is dead and let it to find the
> final rest).
> 
> This is solved by hooking into mem_cgroup_css_offline and checking all
> per-node-zone-priority iterators up the way to the root cgroup. If the
> current memcg is found in the respective iter->last_visited then it is
> replaced by the previous one in the same sub-hierarchy.
> 
> This guarantees that no group gets more reclaiming than necessary and
> the next iteration will continue without noticing that the removed group
> has disappeared.
> 
> Spotted-by: Ying Han <yinghan@...gle.com>
> Signed-off-by: Michal Hocko <mhocko@...e.cz>


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


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