Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753794Ab2FKHIP (ORCPT ); Mon, 11 Jun 2012 03:08:15 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:45280 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751971Ab2FKHIO (ORCPT ); Mon, 11 Jun 2012 03:08:14 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <4FD598C2.8020709@jp.fujitsu.com> Date: Mon, 11 Jun 2012 16:05:38 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Hugh Dickins CC: Andrew Morton , Johannes Weiner , Konstantin Khlebnikov , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] memcg: fix use_hierarchy css_is_ancestor oops regression References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 893 Lines: 19 (2012/06/11 3:54), Hugh Dickins wrote: > If use_hierarchy is set, reclaim testing soon oopses in css_is_ancestor() > called from __mem_cgroup_same_or_subtree() called from page_referenced(): > when processes are exiting, it's easy for mm_match_cgroup() to pass along > a NULL memcg coming from a NULL mm->owner. > > Check for that in __mem_cgroup_same_or_subtree(). Return true or false? > False because we cannot know if it was in the hierarchy, but also false > because it's better not to count a reference from an exiting process. > > Signed-off-by: Hugh Dickins 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/