From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balbir Singh Subject: Re: [-mm] Add an owner to the mm_struct (v7) Date: Fri, 04 Apr 2008 00:18:11 +0530 Message-ID: <47F5266B.2060402@linux.vnet.ibm.com> References: <20080403174433.26356.42121.sendpatchset@localhost.localdomain> <6599ad830804031058l1e2a7ad9p56cff47dca738d79@mail.gmail.com> <47F51DE7.7010204@linux.vnet.ibm.com> <6599ad830804031122y3f6946fbp97dc18073bf02609@mail.gmail.com> <47F5233F.1010108@linux.vnet.ibm.com> <6599ad830804031141o142bf8c2o1899ca78f8cd434a@mail.gmail.com> Reply-To: balbir@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <6599ad830804031141o142bf8c2o1899ca78f8cd434a@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Paul Menage Cc: Pavel Emelianov , Hugh Dickins , Sudhir Kumar , YAMAMOTO Takashi , lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, taka@valinux.co.jp, linux-mm@kvack.org, David Rientjes , Andrew Morton , KAMEZAWA Hiroyuki List-Id: linux-mm.kvack.org Paul Menage wrote: > On Thu, Apr 3, 2008 at 11:34 AM, Balbir Singh wrote: >> That is indeed quite bad. Do we have to retire the group_leader to init_css_set? >> Can we not check for delay_group_leader() there? >> > > That might have unintentded consequences, such as leaving a pid in the > cgroup that can't be moved (since it's PF_EXITING) but won't go away > until its threads have all exited. > Maybe that's OK if the other threads are guaranteed to have started > exiting by this point. We'd need some cleanup for when the group > leader finally did exit. Yes, we might be stuck with an unremovable group, but I am not sure how to address the side-effect at this point. Not having that check could mean that mm_update_new_owner() will be called very frequently and for thousands of threads that could clearly become an overhead, if threads start exiting one by one - lead by the thread group leader. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL