From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx172.postini.com [74.125.245.172]) by kanga.kvack.org (Postfix) with SMTP id ACE016B0108 for ; Fri, 27 Apr 2012 16:33:41 -0400 (EDT) Received: by pbcup15 with SMTP id up15so1687054pbc.14 for ; Fri, 27 Apr 2012 13:33:41 -0700 (PDT) Date: Fri, 27 Apr 2012 13:33:36 -0700 From: Tejun Heo Subject: Re: [RFC][PATCH 7/9 v2] cgroup: avoid attaching task to a cgroup under rmdir() Message-ID: <20120427203336.GM26595@google.com> References: <4F9A327A.6050409@jp.fujitsu.com> <4F9A366E.9020307@jp.fujitsu.com> <20120427203159.GL26595@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120427203159.GL26595@google.com> Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: Linux Kernel , "linux-mm@kvack.org" , "cgroups@vger.kernel.org" , Michal Hocko , Johannes Weiner , Frederic Weisbecker , Glauber Costa , Han Ying , "Aneesh Kumar K.V" , Andrew Morton , kamezawa.hiroyuki@gmail.com On Fri, Apr 27, 2012 at 01:31:59PM -0700, Tejun Heo wrote: > On Fri, Apr 27, 2012 at 03:02:22PM +0900, KAMEZAWA Hiroyuki wrote: > > attach_task() is done under cgroup_mutex() but ->pre_destroy() callback > > in rmdir() isn't called under cgroup_mutex(). > > > > It's better to avoid attaching a task to a cgroup which > > is under pre_destroy(). Considering memcg, the attached task may > > increase resource usage after memcg's pre_destroy() confirms that > > memcg is empty. This is not good. > > > > Signed-off-by: KAMEZAWA Hiroyuki > > Hmm... once memcg's pre_destroy() can't fail, I think what we should > do is marking a cgroup DEAD before calling pre_destroy() and the > existing cgroup_is_removed() check should be enough. Patches upto > this point already make ->pre_destroy() not fail, right? Ooh, I was confused about patch order. This patch, probably with the update suggested by Frederic looks good as an interim solution for now. Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org