Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758675AbZAOCuM (ORCPT ); Wed, 14 Jan 2009 21:50:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753648AbZAOCty (ORCPT ); Wed, 14 Jan 2009 21:49:54 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:33714 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753483AbZAOCtx (ORCPT ); Wed, 14 Jan 2009 21:49:53 -0500 Date: Thu, 15 Jan 2009 11:48:46 +0900 From: KAMEZAWA Hiroyuki To: balbir@linux.vnet.ibm.com Cc: Daisuke Nishimura , LKML , linux-mm , Andrew Morton , Pavel Emelyanov , Li Zefan , Paul Menage Subject: Re: [RFC][PATCH 5/4] memcg: don't call res_counter_uncharge when obsolete Message-Id: <20090115114846.388781a7.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090114135539.GA21516@balbir.in.ibm.com> References: <20090113184533.6ffd2af9.nishimura@mxp.nes.nec.co.jp> <20090114175121.275ecd59.nishimura@mxp.nes.nec.co.jp> <20090114135539.GA21516@balbir.in.ibm.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1390 Lines: 39 On Wed, 14 Jan 2009 19:25:39 +0530 Balbir Singh wrote: > * Daisuke Nishimura [2009-01-14 17:51:21]: > > > This is a new one. Please review. > > > > === > > From: Daisuke Nishimura > > > > mem_cgroup_get ensures that the memcg that has been got can be accessed > > even after the directory has been removed, but it doesn't ensure that parents > > of it can be accessed: parents might have been freed already by rmdir. > > > > This causes a bug in case of use_hierarchy==1, because res_counter_uncharge > > climb up the tree. > > > > Check if the memcg is obsolete, and don't call res_counter_uncharge when obsole. > > > > Signed-off-by: Daisuke Nishimura > > I liked the earlier, EBUSY approach that ensured that parents could > not go away if children exist. IMHO, the code has gotten too complex > and has too many corner cases. Time to revisit it. > It's on my plan. I'll fix this by CSS-ID patch. When I recored memcg's CSS-ID to swap_cgroup (not pointer to memcg), we never need memcg's refcnt. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/