From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758708Ab3FMNcu (ORCPT ); Thu, 13 Jun 2013 09:32:50 -0400 Received: from cantor2.suse.de ([195.135.220.15]:56406 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758334Ab3FMNcq (ORCPT ); Thu, 13 Jun 2013 09:32:46 -0400 Date: Thu, 13 Jun 2013 15:32:44 +0200 From: Michal Hocko To: Richard Weinberger Cc: LKML , "linux-mm@kvack.org" , cgroups mailinglist , "kamezawa.hiroyu@jp.fujitsu.com" , bsingharora@gmail.com, hannes@cmpxchg.org Subject: Re: mem_cgroup_page_lruvec: BUG: unable to handle kernel NULL pointer dereference at 00000000000001a8 Message-ID: <20130613133244.GD23070@dhcp22.suse.cz> References: <20130613120248.GB23070@dhcp22.suse.cz> <51B9B5BC.4090702@nod.at> <20130613132908.GC23070@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130613132908.GC23070@dhcp22.suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ohh and could you post the config please? Sorry should have asked earlier. On Thu 13-06-13 15:29:08, Michal Hocko wrote: > > On Thu 13-06-13 14:06:20, Richard Weinberger wrote: > [...] > > All code > > ======== > > 0: 89 50 08 mov %edx,0x8(%rax) > > 3: 48 89 d1 mov %rdx,%rcx > > 6: 0f 1f 40 00 nopl 0x0(%rax) > > a: 49 8b 04 24 mov (%r12),%rax > > e: 48 89 c2 mov %rax,%rdx > > 11: 48 c1 e8 38 shr $0x38,%rax > > 15: 83 e0 03 and $0x3,%eax > nid = page_to_nid > > 18: 48 c1 ea 3a shr $0x3a,%rdx > zid = page_zonenum > > > 1c: 48 69 c0 38 01 00 00 imul $0x138,%rax,%rax > > 23: 48 03 84 d1 e0 02 00 add 0x2e0(%rcx,%rdx,8),%rax > &memcg->nodeinfo[nid]->zoneinfo[zid] > > > 2a: 00 > > 2b:* 48 3b 58 70 cmp 0x70(%rax),%rbx <-- trapping instruction > > OK, so this maps to: > if (unlikely(lruvec->zone != zone)) <<< > lruvec->zone = zone; > > > [35355.883056] RSP: 0000:ffff88003d523aa8 EFLAGS: 00010002 > > [35355.883056] RAX: 0000000000000138 RBX: ffff88003fffa600 RCX: ffff88003e04a800 > > [35355.883056] RDX: 0000000000000020 RSI: 0000000000000000 RDI: 0000000000028500 > > [35355.883056] RBP: ffff88003d523ab8 R08: 0000000000000000 R09: 0000000000000000 > > [35355.883056] R10: 0000000000000000 R11: dead000000100100 R12: ffffea0000a14000 > > [35355.883056] R13: ffff88003e04b138 R14: ffff88003d523bb8 R15: ffffea0000a14020 > > [35355.883056] FS: 0000000000000000(0000) GS:ffff88003fd80000(0000) > > RAX (lruvec) is obviously incorrect and it doesn't make any sense. rax should > contain an address at an offset from ffff88003e04a800 But there is 0x138 there > instead. > > Is this easily reproducible? Could you configure kdump. -- Michal Hocko SUSE Labs