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 S1752091AbbCQCXo (ORCPT <rfc822;w@1wt.eu>);
	Mon, 16 Mar 2015 22:23:44 -0400
Received: from mx1.redhat.com ([209.132.183.28]:48798 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1750852AbbCQCXn (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Mon, 16 Mar 2015 22:23:43 -0400
Message-ID: <55079005.9000307@redhat.com>
Date: Mon, 16 Mar 2015 22:23:01 -0400
From: Rik van Riel <riel@redhat.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0
MIME-Version: 1.0
To: Laura Abbott <lauraa@codeaurora.org>, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Vlastimil Babka <vbabka@suse.cz>, Gioh Kim <gioh.kim@lge.com>
CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Mel Gorman <mgorman@suse.de>,
        Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
        Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
        Xishi Qiu <qiuxishi@huawei.com>,
        Vladimir Davydov <vdavydov@parallels.com>,
        Michal Nazarewicz <mina86@mina86.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH] mm/page_alloc: Call kernel_map_pages in unset_migrateype_isolate
References: <1426530585-11367-1-git-send-email-lauraa@codeaurora.org>
In-Reply-To: <1426530585-11367-1-git-send-email-lauraa@codeaurora.org>
Content-Type: text/plain; charset=utf-8
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 03/16/2015 02:29 PM, Laura Abbott wrote:
> Commit 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
> changed the logic of unset_migratetype_isolate to check the buddy allocator
> and explicitly call __free_pages to merge. The page that is being freed in
> this path never had prep_new_page called so set_page_refcounted is called
> explicitly but there is no call to kernel_map_pages. With the default
> kernel_map_pages this is mostly harmless but if kernel_map_pages does any
> manipulation of the page tables (unmapping or setting pages to read only) this
> may trigger a fault:
> 
>     alloc_contig_range test_pages_isolated(ceb00, ced00) failed
>     Unable to handle kernel paging request at virtual address ffffffc0cec00000
>     pgd = ffffffc045fc4000
>     [ffffffc0cec00000] *pgd=0000000000000000
>     Internal error: Oops: 9600004f [#1] PREEMPT SMP
>     Modules linked in: exfatfs
>     CPU: 1 PID: 23237 Comm: TimedEventQueue Not tainted 3.10.49-gc72ad36-dirty #1
>     task: ffffffc03de52100 ti: ffffffc015388000 task.ti: ffffffc015388000
>     PC is at memset+0xc8/0x1c0
>     LR is at kernel_map_pages+0x1ec/0x244
> 
> Fix this by calling kernel_map_pages to ensure the page is set in the
> page table properly

Acked-by: Rik van Riel <riel@redhat.com>

-- 
All rights reversed