From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753090Ab0DTEXr (ORCPT <rfc822;w@1wt.eu>);
	Tue, 20 Apr 2010 00:23:47 -0400
Received: from TYO202.gate.nec.co.jp ([202.32.8.206]:57953 "EHLO
	tyo202.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1750879Ab0DTEXq (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 20 Apr 2010 00:23:46 -0400
Date: Tue, 20 Apr 2010 13:20:50 +0900
From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>,
       Mel Gorman <mel@csn.ul.ie>, Rik van Riel <riel@redhat.com>,
       Minchan Kim <minchan.kim@gmail.com>,
       Balbir Singh <balbir@linux.vnet.ibm.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Christoph Lameter <cl@linux-foundation.org>,
       Andrea Arcangeli <aarcange@redhat.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Subject: Re: [RFC][BUGFIX][PATCH 2/2] memcg: fix file mapped underflow at
 migration (v3)
Message-Id: <20100420132050.3477a717.nishimura@mxp.nes.nec.co.jp>
In-Reply-To: <20100419172629.dbf65e18.kamezawa.hiroyu@jp.fujitsu.com>
References: <20100413134207.f12cdc9c.nishimura@mxp.nes.nec.co.jp>
	<20100415120516.3891ce46.kamezawa.hiroyu@jp.fujitsu.com>
	<20100415120652.c577846f.kamezawa.hiroyu@jp.fujitsu.com>
	<20100416193143.5807d114.kamezawa.hiroyu@jp.fujitsu.com>
	<20100419124225.91f3110b.nishimura@mxp.nes.nec.co.jp>
	<20100419131817.f263d93c.kamezawa.hiroyu@jp.fujitsu.com>
	<20100419170701.3864992e.nishimura@mxp.nes.nec.co.jp>
	<20100419172629.dbf65e18.kamezawa.hiroyu@jp.fujitsu.com>
Organization: NEC Soft, Ltd.
X-Mailer: Sylpheed 2.6.0 (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: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> > I have one concern for now. Reading the patch, the flag have influence on
> > only anonymous pages, so we'd better to note it and I feel it strange to
> > set(and clear) the flag of "old page" always(iow, even when !PageAnon)
> > in prepare_migration.
> > 
> 
> Hmm...Checking "Only Anon" is simpler ?
I just thought it was inconsistent that we always set/clear the bit about "old page",
while we set the bit about "new page" only in PageAnon case.

> It will have no meanings for migrating
> file caches, but it may have some meanings for easy debugging. 
> I think "mark it always but it's used only for anonymous page" is reasonable
> (if it causes no bug.)
> 
Anyway, I don't have any strong objection.
It's all right for me as long as it is well documented or commented.


Thanks,
Daisuke Nishimura.