From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753404Ab1HRF44 (ORCPT ); Thu, 18 Aug 2011 01:56:56 -0400 Received: from cantor2.suse.de ([195.135.220.15]:34222 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751127Ab1HRF4y (ORCPT ); Thu, 18 Aug 2011 01:56:54 -0400 Date: Thu, 18 Aug 2011 07:56:49 +0200 From: Michal Hocko To: Johannes Weiner Cc: KAMEZAWA Hiroyuki , linux-mm@kvack.org, Balbir Singh , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [patch] memcg: pin execution to current cpu while draining stock Message-ID: <20110818055649.GA23056@tiehlicka.suse.cz> References: <2f17df54db6661c39a05669d08a9e6257435b898.1311338634.git.mhocko@suse.cz> <20110725101657.21f85bf0.kamezawa.hiroyu@jp.fujitsu.com> <20110817194927.GA10982@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110817194927.GA10982@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 17-08-11 21:49:27, Johannes Weiner wrote: > Commit d1a05b6 'memcg: do not try to drain per-cpu caches without > pages' added a drain_local_stock() call to a preemptible section. > > The draining task looks up the cpu-local stock twice to set the > draining-flag, then to drain the stock and clear the flag again. If > the task is migrated to a different CPU in between, noone will clear > the flag on the first stock and it will be forever undrainable. Its > charge can not be recovered and the cgroup can not be deleted anymore. > > Properly pin the task to the executing CPU while draining stocks. > > Signed-off-by: Johannes Weiner > Cc: KAMEZAWA Hiroyuki Cc: Michal Hocko My fault, I didn't realize that drain_local_stock needs preemption disabled. Sorry about that and good work, Johannes. Acked-by: Michal Hocko -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic