Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936742Ab3DICwA (ORCPT ); Mon, 8 Apr 2013 22:52:00 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:60554 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934470Ab3DICv7 (ORCPT ); Mon, 8 Apr 2013 22:51:59 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.8.4 Message-ID: <5163823B.4020109@jp.fujitsu.com> Date: Tue, 09 Apr 2013 11:51:39 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130328 Thunderbird/17.0.5 MIME-Version: 1.0 To: Li Zefan CC: Andrew Morton , Tejun Heo , Glauber Costa , Johannes Weiner , LKML , Cgroups , linux-mm@kvack.org Subject: Re: [PATCH 04/12] memcg, kmem: fix reference count handling on the error path References: <5162648B.9070802@huawei.com> <516264D6.3090100@huawei.com> In-Reply-To: <516264D6.3090100@huawei.com> Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1502 Lines: 34 (2013/04/08 15:33), Li Zefan wrote: > From: Michal Hocko > > mem_cgroup_css_online calls mem_cgroup_put if memcg_init_kmem > fails. This is not correct because only memcg_propagate_kmem takes an > additional reference while mem_cgroup_sockets_init is allowed to fail as > well (although no current implementation fails) but it doesn't take any > reference. This all suggests that it should be memcg_propagate_kmem that > should clean up after itself so this patch moves mem_cgroup_put over > there. > > Unfortunately this is not that easy (as pointed out by Li Zefan) because > memcg_kmem_mark_dead marks the group dead (KMEM_ACCOUNTED_DEAD) if it > is marked active (KMEM_ACCOUNTED_ACTIVE) which is the case even if > memcg_propagate_kmem fails so the additional reference is dropped in > that case in kmem_cgroup_destroy which means that the reference would be > dropped two times. > > The easiest way then would be to simply remove mem_cgrroup_put from > mem_cgroup_css_online and rely on kmem_cgroup_destroy doing the right > thing. > > Signed-off-by: Li Zefan > Signed-off-by: Michal Hocko > Cc: # 3.8.x Acked-by: KAMEZAWA Hiroyuki -- 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/