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 S1754108AbaCKEmQ (ORCPT <rfc822;w@1wt.eu>);
	Tue, 11 Mar 2014 00:42:16 -0400
Received: from mail.linuxfoundation.org ([140.211.169.12]:38419 "EHLO
	mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753639AbaCKEls (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 11 Mar 2014 00:41:48 -0400
Date: Mon, 10 Mar 2014 21:46:12 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Dave Jones <davej@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>,
        linux-mm@kvack.org, Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sasha.levin@oracle.com>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Wanpeng Li <liwanp@linux.vnet.ibm.com>, Bob Liu <bob.liu@oracle.com>,
        Konstantin Khlebnikov <koct9i@gmail.com>
Subject: Re: bad rss-counter message in 3.14rc5
Message-Id: <20140310214612.3b4de36a.akpm@linux-foundation.org>
In-Reply-To: <20140310201340.81994295.akpm@linux-foundation.org>
References: <20140305174503.GA16335@redhat.com>
	<20140305175725.GB16335@redhat.com>
	<20140307002210.GA26603@redhat.com>
	<20140311024906.GA9191@redhat.com>
	<20140310201340.81994295.akpm@linux-foundation.org>
X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu)
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

On Mon, 10 Mar 2014 20:13:40 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:

> > Anyone ? I'm hitting this trace on an almost daily basis, which is a pain
> > while trying to reproduce a different bug..
> 
> Damn, I thought we'd fixed that but it seems not.  Cc's added.
> 
> Guys, what stops the migration target page from coming unlocked in
> parallel with zap_pte_range()'s call to migration_entry_to_page()?

page_table_lock, sort-of.  At least, transitions of is_migration_entry()
and page_locked() happen under ptl.

I don't see any holes in regular migration.  Do you know if this is
reproducible with CONFIG_NUMA_BALANCING=n or CONFIG_NUMA=n?