From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 079E86B0062 for ; Thu, 17 Dec 2009 02:31:03 -0500 (EST) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id nBH7V0NR014056 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 17 Dec 2009 16:31:01 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id A63E445DE51 for ; Thu, 17 Dec 2009 16:31:00 +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 7610145DE55 for ; Thu, 17 Dec 2009 16:31:00 +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 5E1AB1DB8041 for ; Thu, 17 Dec 2009 16:31:00 +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 F24421DB8038 for ; Thu, 17 Dec 2009 16:30:59 +0900 (JST) Date: Thu, 17 Dec 2009 16:27:44 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH -mmotm 0/8] memcg: move charge at task migration (14/Dec) Message-Id: <20091217162744.e09a271a.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20091217160009.57eb946f.nishimura@mxp.nes.nec.co.jp> References: <20091214151748.bf9c4978.nishimura@mxp.nes.nec.co.jp> <20091215033000.GD6036@balbir.in.ibm.com> <20091215131421.00b87ad1.nishimura@mxp.nes.nec.co.jp> <20091217160009.57eb946f.nishimura@mxp.nes.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Daisuke Nishimura Cc: balbir@linux.vnet.ibm.com, linux-mm , Andrew Morton , Li Zefan , Paul Menage List-ID: On Thu, 17 Dec 2009 16:00:09 +0900 Daisuke Nishimura wrote: > On Tue, 15 Dec 2009 13:14:21 +0900, Daisuke Nishimura wrote: > > On Tue, 15 Dec 2009 09:00:00 +0530, Balbir Singh wrote: > > > * nishimura@mxp.nes.nec.co.jp [2009-12-14 15:17:48]: > > > > > > > Hi. > > > > > > > > These are current patches of my move-charge-at-task-migration feature. > > > > > > > > * They have not been mature enough to be merged into linus tree yet. * > > > > > > > > Actually, there is a NULL pointer dereference BUG, which I found in my stress > > > > test after about 40 hours running and I'm digging now. > > > > I post these patches just to share my current status. > > > > > > > Could this be because of the css_get() and css_put() changes from the > > > previous release? > > > > > I suspect so. Perhaps, [5/8] or [8/8] might be the guilt. > > > > I'm now running test without [8/8]. It has survived for 24h so far, but > > I must run for more time to verify it's all right or not. > > I'm also looking closely into my patches again. > > > I think I get the cause of this bug. > > In [8/8], I postponed calling mem_cgroup_get() till the end of task migration > (i.e. I called __mem_cgroup_get() in mem_cgroup_clear_mc()). > But if a process which has been moved to a new group does swap-in, it calls > mem_cgroup_put() against the new mem_cgroup. This means the mem_cgroup->refcnt > of the new group might be decreased to 0, so that the mem_cgroup can be freed > (__mem_cgroup_free() is called) unexpectedly. > > I'll fix this by not postponing mem_cgroup_get(postponing mem_cgroup_put() would be > all right), and test it during this weekend. > > Great!. Thank you for your efforts. Thanks, -Kame -- 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