From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx194.postini.com [74.125.245.194]) by kanga.kvack.org (Postfix) with SMTP id 9F8FD6B006E for ; Mon, 29 Oct 2012 11:09:44 -0400 (EDT) Message-ID: <508E9C28.1000308@parallels.com> Date: Mon, 29 Oct 2012 19:09:28 +0400 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH v3 3/6] memcg: Simplify mem_cgroup_force_empty_list error handling References: <1351251453-6140-1-git-send-email-mhocko@suse.cz> <1351251453-6140-4-git-send-email-mhocko@suse.cz> <508E8B95.406@parallels.com> <20121029141534.GB20757@dhcp22.suse.cz> In-Reply-To: <20121029141534.GB20757@dhcp22.suse.cz> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , Tejun Heo , Li Zefan , Johannes Weiner , KAMEZAWA Hiroyuki , Balbir Singh >>> + * move charges to its parent or the root cgroup if the group has no >>> + * parent (aka use_hierarchy==0). >>> + * Although this might fail (get_page_unless_zero, isolate_lru_page or >>> + * mem_cgroup_move_account fails) the failure is always temporary and >>> + * it signals a race with a page removal/uncharge or migration. In the >>> + * first case the page is on the way out and it will vanish from the LRU >>> + * on the next attempt and the call should be retried later. >>> + * Isolation from the LRU fails only if page has been isolated from >>> + * the LRU since we looked at it and that usually means either global >>> + * reclaim or migration going on. The page will either get back to the >>> + * LRU or vanish. >> >> I just wonder for how long can it go in the worst case? > > That's a good question and to be honest I have no idea. The point is > that it will terminate eventually and that the group is on the way out > so the time to complete the removal is not a big deal IMHO. We had > basically similar situation previously when we would need to repeat > rmdir loop on EBUSY. The only change is that we do not have to retry > anymore. > > So the key point is to check whether my assumption about temporarily is > correct and that we cannot block the rest of the kernel/userspace to > proceed even though we are waiting for finalization. I believe this is > true but... (last famous words?) > At least for me, it seems that this will hold. -- 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/ . Don't email: email@kvack.org