From: KAMEZAWA Hiroyuki Subject: Re: [PATCH v1 0/7] memcg remove pre_destroy Date: Wed, 18 Apr 2012 16:15:12 +0900 Message-ID: <4F8E6A00.50707@jp.fujitsu.com> References: <4F86B9BE.8000105@jp.fujitsu.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Ying Han Cc: "linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org" , "cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Michal Hocko , Johannes Weiner , Tejun Heo , Glauber Costa , Hugh Dickins , Andrew Morton (2012/04/18 2:35), Ying Han wrote: > On Thu, Apr 12, 2012 at 4:17 AM, KAMEZAWA Hiroyuki > wrote: >> In recent discussion, Tejun Heo, cgroup maintainer, has a plan to remove >> ->pre_destroy(). And now, in cgroup tree, pre_destroy() failure cause WARNING. >> >> By pre_destroy(), rmdir of cgroup can return -EBUSY or some error. >> It makes cgroup complicated and unstable. I said O.K. to remove it and >> this patch is modification for memcg. >> >> One of problem in current implementation is that memcg moves all charges to >> parent in pre_destroy(). At doing so, if use_hierarchy=0, pre_destroy() may >> hit parent's limit and may return -EBUSY. To fix this problem, this patch >> changes behavior of rmdir() as >> >> - if use_hierarchy=0, all remaining charges will go to root cgroup. >> - if use_hierarchy=1, all remaining charges will go to the parent. > > > We need to update the "4.3 Removing a cgroup" session in Documentation. > Sure, will do. Thanks, -Kame