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 C8BC26B004A for ; Fri, 10 Jun 2011 00:02:51 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 9BFDA3EE0C0 for ; Fri, 10 Jun 2011 13:02:46 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 8677645DE9D for ; Fri, 10 Jun 2011 13:02:46 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 6EE7545DE9B for ; Fri, 10 Jun 2011 13:02:46 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 636BA1DB8038 for ; Fri, 10 Jun 2011 13:02:46 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.240.81.146]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 2DC761DB802C for ; Fri, 10 Jun 2011 13:02:46 +0900 (JST) Date: Fri, 10 Jun 2011 12:55:51 +0900 From: KAMEZAWA Hiroyuki Subject: Re: 3.0rc2 oops in mem_cgroup_from_task Message-Id: <20110610125551.385ea7ed.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110610121949.622e4629.kamezawa.hiroyu@jp.fujitsu.com> References: <20110609212956.GA2319@redhat.com> <20110610091355.2ce38798.kamezawa.hiroyu@jp.fujitsu.com> <20110610113311.409bb423.kamezawa.hiroyu@jp.fujitsu.com> <20110610121949.622e4629.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: Hugh Dickins , Ying Han , Dave Jones , Linux Kernel , "linux-mm@kvack.org" On Fri, 10 Jun 2011 12:19:49 +0900 KAMEZAWA Hiroyuki wrote: > On Fri, 10 Jun 2011 11:33:11 +0900 > KAMEZAWA Hiroyuki wrote: > > > On Thu, 9 Jun 2011 18:30:49 -0700 (PDT) > > Hugh Dickins wrote: > > > > 781cc621 : > > > 781cc621: 55 push %ebp > > > 781cc622: 31 c0 xor %eax,%eax > > > 781cc624: 89 e5 mov %esp,%ebp > > > 781cc626: 8b 55 08 mov 0x8(%ebp),%edx > > > 781cc629: 85 d2 test %edx,%edx > > > 781cc62b: 74 09 je 781cc636 > > > 781cc62d: 8b 82 fc 08 00 00 mov 0x8fc(%edx),%eax > > > 781cc633: 8b 40 1c mov 0x1c(%eax),%eax <========== > > > 781cc636: c9 leave > > > 781cc637: c3 ret > > > > > > > then, access to task->cgroups->subsys[?] causes access to 6b6b6b87... > > > > Then, task->cgroups or task->cgroups->subsys contains bad pointer. > > Considering khugepaged, it grabs mm_struct and memcg make an access to > > (mm->owner)->cgroups->subsys. > > > > Then, from memcg's point of view, we need to doubt mm->owner is valid or not > > for this kind of tasks. > > > > Dave's log shows 6b6b6b6b6b..., too. > > I guess it as "POISON_FREE" of slab object. Then, task->cgroups may used after free. > Ah, sorry. 0x1c(%eax) == 6b6b6b87 means %eax was 0x6b6b6b6b. The %eax was the contents of [task->cgroups]....hmm, then, task itself is freed pointer (and poisoned). So, it seems a problem of accessing mm->owner.. Thanks, -Kame -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org