Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764138AbZAIBGp (ORCPT ); Thu, 8 Jan 2009 20:06:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760557AbZAIBGg (ORCPT ); Thu, 8 Jan 2009 20:06:36 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:60492 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760549AbZAIBGf (ORCPT ); Thu, 8 Jan 2009 20:06:35 -0500 Date: Fri, 9 Jan 2009 10:05:31 +0900 From: KAMEZAWA Hiroyuki To: Li Zefan Cc: Daisuke Nishimura , linux-mm@kvack.org, linux-kernel@vger.kernel.org, balbir@linux.vnet.ibm.com, menage@google.com Subject: Re: [RFC][PATCH 1/4] memcg: fix for mem_cgroup_get_reclaim_stat_from_page Message-Id: <20090109100531.03cd998f.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <4966A117.9030201@cn.fujitsu.com> References: <20090108190818.b663ce20.nishimura@mxp.nes.nec.co.jp> <20090108191430.af89e037.nishimura@mxp.nes.nec.co.jp> <4966A117.9030201@cn.fujitsu.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: 929 Lines: 32 On Fri, 09 Jan 2009 08:57:59 +0800 Li Zefan wrote: > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index e2996b8..62e69d8 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -559,6 +559,10 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page) > > return NULL; > > > > pc = lookup_page_cgroup(page); > > + smp_rmb(); > > It is better to add a comment to explain this smp_rmb. I think it's recommended > that every memory barrier has a comment. > Ah, yes. good point. Maybe text like this /* * Used bit is set without atomic ops but after smp_wmb(). * For making pc->mem_cgroup visible, insert smp_rmb() here. */ ? -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/