From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id DD7136B01EE for ; Thu, 1 Apr 2010 15:03:56 -0400 (EDT) Received: from wpaz9.hot.corp.google.com (wpaz9.hot.corp.google.com [172.24.198.73]) by smtp-out.google.com with ESMTP id o31J3nsw016616 for ; Thu, 1 Apr 2010 12:03:49 -0700 Received: from pwi5 (pwi5.prod.google.com [10.241.219.5]) by wpaz9.hot.corp.google.com with ESMTP id o31J3gx7029053 for ; Thu, 1 Apr 2010 12:03:43 -0700 Received: by pwi5 with SMTP id 5so1319426pwi.19 for ; Thu, 01 Apr 2010 12:03:42 -0700 (PDT) Date: Thu, 1 Apr 2010 12:03:39 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH 1/1] oom: fix the unsafe usage of badness() in proc_oom_score() In-Reply-To: <20100401131357.GB11291@redhat.com> Message-ID: References: <20100328162821.GA16765@redhat.com> <20100329112111.GA16971@redhat.com> <20100330163909.GA16884@redhat.com> <20100331091628.GA11438@redhat.com> <20100331201746.GC11635@redhat.com> <20100401131321.GA11291@redhat.com> <20100401131357.GB11291@redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Oleg Nesterov Cc: Andrew Morton , Linus Torvalds , anfei , KOSAKI Motohiro , nishimura@mxp.nes.nec.co.jp, KAMEZAWA Hiroyuki , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@kernel.org List-ID: On Thu, 1 Apr 2010, Oleg Nesterov wrote: > proc_oom_score(task) have a reference to task_struct, but that is all. > If this task was already released before we take tasklist_lock > > - we can't use task->group_leader, it points to nowhere > > - it is not safe to call badness() even if this task is > ->group_leader, has_intersects_mems_allowed() assumes > it is safe to iterate over ->thread_group list. > > - even worse, badness() can hit ->signal == NULL > > Add the pid_alive() check to ensure __unhash_process() was not called. > > Also, use "task" instead of task->group_leader. badness() should return > the same result for any sub-thread. Currently this is not true, but > this should be changed anyway. > > Signed-off-by: Oleg Nesterov Acked-by: David Rientjes Andrew, this is 2.6.34 material and should be backported to stable. It's not introduced by the recent oom killer rewrite pending in -mm, but it will require a trivial merge resolution on that work. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org