From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 064BF6B006A for ; Wed, 14 Jan 2009 22:25:26 -0500 (EST) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n0F3PM0W025588 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 15 Jan 2009 12:25:24 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id F279745DE57 for ; Thu, 15 Jan 2009 12:25:21 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id D073045DE51 for ; Thu, 15 Jan 2009 12:25:21 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id B61D21DB8043 for ; Thu, 15 Jan 2009 12:25:21 +0900 (JST) Received: from m108.s.css.fujitsu.com (m108.s.css.fujitsu.com [10.249.87.108]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 689141DB803B for ; Thu, 15 Jan 2009 12:25:21 +0900 (JST) Date: Thu, 15 Jan 2009 12:24:16 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC][PATCH 5/4] memcg: don't call res_counter_uncharge when obsolete Message-Id: <20090115122416.e15d88a7.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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: balbir@linux.vnet.ibm.com Cc: Daisuke Nishimura , LKML , linux-mm , Andrew Morton , Pavel Emelyanov , Li Zefan , Paul Menage List-ID: 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 Check if the memcg is obsolete, and don't call res_counter_uncharge when obsole.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. > But I don't like -EBUSY ;) When rmdir() returns -EBUSY even if there are no (visible) children and tasks, our customer will take kdump and send it to me "please explain this kernel bug" I'm sure it will happen ;) -Kame > -- > Balbir > -- 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