From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756723AbcAYKr5 (ORCPT ); Mon, 25 Jan 2016 05:47:57 -0500 Received: from mail-wm0-f48.google.com ([74.125.82.48]:33864 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756554AbcAYKrw (ORCPT ); Mon, 25 Jan 2016 05:47:52 -0500 Date: Mon, 25 Jan 2016 12:47:49 +0200 From: "Kirill A. Shutemov" To: Borislav Petkov Cc: linux-mm@kvack.org, Andrew Morton , "Kirill A. Shutemov" , Vlastimil Babka , Jerome Marchand , Mel Gorman , Ebru Akagunduz , Dan Williams , Minchan Kim , linux-kernel@vger.kernel.org Subject: Re: khugepaged+0x5a6/0x1800 - BUG: unable to handle kernel NULL pointer dereference at (null) Message-ID: <20160125104749.GA11541@node.shutemov.name> References: <20160122181450.GI9806@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160122181450.GI9806@pd.tnic> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 22, 2016 at 07:14:50PM +0100, Borislav Petkov wrote: > Hi guys, > > I'm getting this null ptr deref below ontop of latest Linus, i.e. > top-commit is: > > 2b4015e9fb33 ("Merge tag 'platform-drivers-x86-v4.5-1' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86") > > The good thing is, it is reproducible even in kvm, 32-bit guest. > > Thoughts? I think 16fd0fe4aa92 ("mm: fix kernel crash in khugepaged thread") would fix this. > > [ 6.058923] BUG: unable to handle kernel NULL pointer dereference at (null) > [ 6.059496] IP: [] khugepaged+0x5a6/0x1800 > [ 6.059496] *pde = 00000000 > [ 6.059496] Oops: 0000 [#1] PREEMPT SMP > [ 6.059496] Modules linked in: > [ 6.059496] CPU: 2 PID: 33 Comm: khugepaged Not tainted 4.4.0+ #2 > [ 6.059496] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014 > [ 6.059496] task: f5222e80 ti: f522a000 task.ti: f522a000 > [ 6.059496] EIP: 0060:[] EFLAGS: 00010246 CPU: 2 > [ 6.059496] EIP is at khugepaged+0x5a6/0x1800 > [ 6.059496] EAX: 00000000 EBX: 00000003 ECX: 00000000 EDX: 00000000 > [ 6.059496] ESI: f40412c0 EDI: f451cf00 EBP: f522bf30 ESP: f522be88 > [ 6.059496] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 > [ 6.059496] CR0: 80050033 CR2: 00000000 CR3: 3410f000 CR4: 000406d0 > [ 6.059496] Stack: > [ 6.059496] 00000000 f57c1780 f511be00 f522be9c f57c1780 f522bea8 c1697c52 f57c1780 > [ 6.059496] f522bee0 f451cf34 f5222e80 00000001 f61e5000 c107d930 f40412c0 f451cf54 > [ 6.059496] 00000000 00002000 f5222e80 f5222e80 00000000 00000000 b6400000 00002000 > [ 6.059496] Call Trace: > [ 6.059496] [] ? _raw_spin_unlock_irq+0x32/0x50 > [ 6.059496] [] ? finish_task_switch+0x60/0x260 > [ 6.059496] [] ? wait_woken+0x80/0x80 > [ 6.059496] [] ? unfreeze_page+0x430/0x430 > [ 6.059496] [] kthread+0xb3/0xd0 > [ 6.059496] [] ret_from_kernel_thread+0x21/0x38 > [ 6.059496] [] ? kthread_create_on_node+0x180/0x180 > [ 6.059496] Code: 75 0b 8b 41 14 a8 01 0f 84 60 01 00 00 89 4d c4 89 4d a8 c7 45 c8 0d 00 00 00 89 f8 e8 84 8c 4f 00 c7 45 ac 00 00 00 00 8b 45 c4 <8b> 00 c1 e8 1a 8b 04 c5 c0 3f 44 c2 89 45 98 3e 8d 74 26 00 64 > [ 6.059496] EIP: [] khugepaged+0x5a6/0x1800 SS:ESP 0068:f522be88 > [ 6.059496] CR2: 0000000000000000 > [ 6.059496] ---[ end trace 71a830f72f820be9 ]--- > > -- > Regards/Gruss, > Boris. > > ECO tip #101: Trim your mails when you reply. -- Kirill A. Shutemov