From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932630AbcEXJRO (ORCPT ); Tue, 24 May 2016 05:17:14 -0400 Received: from mail-am1on0117.outbound.protection.outlook.com ([157.56.112.117]:39872 "EHLO emea01-am1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932612AbcEXJRJ (ORCPT ); Tue, 24 May 2016 05:17:09 -0400 Authentication-Results: kernel.org; dkim=none (message not signed) header.d=none;kernel.org; dmarc=none action=none header.from=virtuozzo.com; Date: Tue, 24 May 2016 12:01:42 +0300 From: Vladimir Davydov To: Michal Hocko CC: Andrew Morton , Johannes Weiner , , Subject: Re: [PATCH] mm: memcontrol: fix possible css ref leak on oom Message-ID: <20160524090142.GI7917@esperanza> References: <1464019330-7579-1-git-send-email-vdavydov@virtuozzo.com> <20160523174441.GA32715@dhcp22.suse.cz> <20160524084319.GH7917@esperanza> <20160524084737.GC8259@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; 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X-Microsoft-Exchange-Diagnostics: 1;AM3PR08MB0579;23: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 X-Microsoft-Exchange-Diagnostics: 1;AM3PR08MB0579;5:s29aL2mrzuvIvWaDr3wE8pIbHyGcHocd9Egti/a9DTNZGkjx+IoFRlzjOUc/yVcloSzQEOhBFIvyZ41we7Tq2lQ7ff4NJvOUKHJzITgQT8dX35SNdUpYqtyH3OfSzk9cjiAYLHjP1ZHFfO1LW4BZuA==;24:ZeW5WSmUBoB2wNd76RLhXA07Dgdg3Ay/pg26jSkQwXFTwLTyV7BcMStnUGMWhUP5OZ/vxbAYHsZ9frI8Gy+LuVwEL//ptQ7ziGV2ZywlkmY=;7:4wWWtw/sncQ1zc+fL5m7rOUc/UsLPZDFd+SqtJK040MU4tNK+jwoByDDHMfebi34v4P1IpEUp16GBIcXFcp/e4lL2YS4RXrIZC5jP9qA5Vsvtfa5EHoeYrWjuJW8N74Xt9RIQPdzBHjD2mbeSkdKN4tQOe7aO+Wbm/Q56RonXCiVS8JKqd3CGQA5UyP/X90z;20:OGdUj01Uo7mdFSOVgs+5jiRGXWiIiQnQIbffMCOwP6hUcul6U7kjLIEsy7gWs8JpsFUBuxMN/6EVuMmPju8EiixH+zJr4uzwN1FrB6BAH5G3P7vrmEzZZtNA3tISRrzkOAMHHWNmgt9Uz53lPKih6Tyg767qfjrP1eeAYwejSBg= SpamDiagnosticOutput: 1:23 SpamDiagnosticMetadata: NSPM X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 May 2016 09:01:46.7299 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM3PR08MB0579 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 24, 2016 at 10:47:37AM +0200, Michal Hocko wrote: > On Tue 24-05-16 11:43:19, Vladimir Davydov wrote: > > On Mon, May 23, 2016 at 07:44:43PM +0200, Michal Hocko wrote: > > > On Mon 23-05-16 19:02:10, Vladimir Davydov wrote: > > > > mem_cgroup_oom may be invoked multiple times while a process is handling > > > > a page fault, in which case current->memcg_in_oom will be overwritten > > > > leaking the previously taken css reference. > > > > > > Have you seen this happening? I was under impression that the page fault > > > paths that have oom enabled will not retry allocations. > > > > filemap_fault will, for readahead. > > I thought that the readahead is __GFP_NORETRY so we do not trigger OOM > killer. Hmm, interesting. We do allocate readahead pages with __GFP_NORETRY, but we add them to page cache and hence charge with GFP_KERNEL or GFP_NOFS mask, see __do_page_cache_readahaed -> read_pages.