From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750770AbWFAVnR (ORCPT ); Thu, 1 Jun 2006 17:43:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750840AbWFAVnQ (ORCPT ); Thu, 1 Jun 2006 17:43:16 -0400 Received: from liaag2aa.mx.compuserve.com ([149.174.40.154]:51848 "EHLO liaag2aa.mx.compuserve.com") by vger.kernel.org with ESMTP id S1750770AbWFAVnP (ORCPT ); Thu, 1 Jun 2006 17:43:15 -0400 Date: Thu, 1 Jun 2006 17:39:09 -0400 From: Chuck Ebbert <76306.1226@compuserve.com> Subject: Re: 2.6.17-rc5-mm1 To: Laurent Riffard Cc: Andrew Morton , linux-kernel Message-ID: <200606011741_MC3-1-C158-4568@compuserve.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In-Reply-To: <447DD4D3.3060205@free.fr> On Wed, 31 May 2006 19:39:31 +0200, Laurent Riffard wrote: > pktcdvd: writer pktcdvd0 mapped to hdc > BUG: unable to handle kernel NULL pointer dereference at virtual address 00000084 > printing eip: > c01118f1 > *pde = 00000000 > Oops: 0000 [#1] > last sysfs file: /block/pktcdvd0/removable > Modules linked in: pktcdvd lp parport_pc parport snd_pcm_oss snd_mixer_oss snd_ens1371 gameport snd_rawmidi snd_seq_device snd_ac97_codec snd_ac97_bus snd_pcm snd_timer snd_page_alloc snd soundcore af_packet floppy ide_cd cdrom loop aes dm_crypt nl > CPU: 0 > EIP: 0060:[] Not tainted VLI > EFLAGS: 00010006 (2.6.17-rc5-mm1 #11) > EIP is at do_page_fault+0xb4/0x5bc > eax: d6750084 ebx: d6750000 ecx: 0000007b edx: 00000000 > esi: d6758000 edi: c011183d ebp: d675007c esp: d6750044 > ds: 007b es: 007b ss: 0068 > Process (pid: 0, threadinfo=d674f000 task=d657c000) > Stack: 00000000 d6750084 00000000 00000049 00000084 00000000 00001e2e 02001120 > 00000027 00000022 00000055 d6750000 d6758000 c011183d d67500f0 c010340d > d6750000 0000007b 00000000 d6758000 c011183d d67500f0 d67500f8 0000007b > Call Trace: > [] error_code+0x39/0x40 > Code: 00 00 c0 81 0f 84 12 02 00 00 e9 1c 05 00 00 8b 45 cc f7 40 30 00 02 02 00 74 06 e8 68 af 01 00 fb f7 43 14 ff ff ff ef 8b 55 d0 <8b> b2 84 00 00 00 0f 85 e5 01 00 00 85 f6 0f 84 dd 01 00 00 8d > EIP: [] do_page_fault+0xb4/0x5bc SS:ESP 0068:d6750044 arch/i386/mm/fault.c::do_page_fault(): 12: f7 40 30 00 02 02 00 testl $0x20200,0x30(%eax) 19: 74 06 je 21 <_EIP+0x21> if (regs->eflags & (X86_EFLAGS_IF|VM_MASK)) 1b: e8 68 af 01 00 call 1af88 <_EIP+0x1af88> 20: fb sti local_irq_enable(); local_irq_enable() should only be doing an sti; your code has an extra function call. Do you have any extra patches applied? 21: f7 43 14 ff ff ff ef testl $0xefffffff,0x14(%ebx) if (in_atomic()... 28: 8b 55 d0 mov 0xffffffd0(%ebp),%edx Get tsk from local storage and put it in edx. 00000000 <_EIP>: 0: 8b b2 84 00 00 00 mov 0x84(%edx),%esi <===== mm = tsk->mm; tsk was zero here, implying that current was 0 when the page fault happened. 6: 0f 85 e5 01 00 00 jne 1f1 <_EIP+0x1f1> c: 85 f6 test %esi,%esi e: 0f 84 dd 01 00 00 je 1f1 <_EIP+0x1f1> Andrew, should we add debug code to the fault handler to test for current == 0? -- Chuck