From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: mmotm 2008-11-26-17-00 uploaded Date: Wed, 3 Dec 2008 07:52:54 -0800 Message-ID: <20081203075254.3bcb3220@extreme> References: <200811270101.mAR114rp016378@imap1.linux-foundation.org> <200811282209.FDC95384.tLQJFOFOHFMSOV@I-love.SAKURA.ne.jp> <20081128114257.a651b9ee.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Tetsuo Handa , linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Andrew Morton Return-path: Received: from mail.vyatta.com ([76.74.103.46]:45998 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751138AbYLCPw5 (ORCPT ); Wed, 3 Dec 2008 10:52:57 -0500 In-Reply-To: <20081128114257.a651b9ee.akpm@linux-foundation.org> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 28 Nov 2008 11:42:57 -0800 Andrew Morton wrote: > On Fri, 28 Nov 2008 22:09:06 +0900 Tetsuo Handa wrote: > > > > The mm-of-the-moment snapshot 2008-11-26-17-00 has been uploaded to > > I got below bug. > > CentOS 5.2 (gcc (GCC) 4.1.2 20071124 (Red Hat 4.1.2-42)) on VMware Workstation 6.5.1. > > > > [ 24.978638] BUG: unable to handle kernel NULL pointer dereference at 00000004 > > [ 24.980541] IP: [] loopback_get_stats+0x26/0x51 > > [ 24.982191] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC > > [ 24.982989] last sysfs file: /sys/class/firmware/microcode/loading > > [ 24.982989] Modules linked in: rfkill input_polldev sbs sbshc battery floppy serio_raw rtc_cmos rtc_core rtc_lib ac button pcnet32 mii i2c_piix4 i2c_core mptspi mptscsih mptbase scsi_transport_spi ext3 jbd mbcache [last unloaded: microcode] > > [ 24.982989] > > [ 24.982989] Pid: 2213, comm: sadc Not tainted (2.6.28-rc6-mm1 #1) VMware Virtual Platform > > [ 24.982989] EIP: 0060:[] EFLAGS: 00010297 CPU: 0 > > [ 24.982989] EIP is at loopback_get_stats+0x26/0x51 > > [ 24.982989] EAX: 00000000 EBX: debf8848 ECX: 00000001 EDX: 00000001 > > [ 24.982989] ESI: 00000000 EDI: 00000000 EBP: de7b9efc ESP: de7b9eec > > [ 24.982989] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 > > [ 24.982989] Process sadc (pid: 2213, ti=de7b9000 task=de5fc0b0 task.ti=de7b9000) > > [ 24.982989] Stack: > > [ 24.982989] 21415ecf debf8800 ddc2fda0 ddc2fda0 de7b9f04 c05a71be de7b9f14 c05a7613 > > [ 24.982989] c062db2c debf8800 de7b9f54 c049d8be 00001000 b7d58000 ddf08310 ddc2fdc0 > > [ 24.982989] 00000000 00000000 000000c8 00000001 00000000 00000000 00000000 fffffffb > > [ 24.982989] Call Trace: > > [ 24.982989] [] ? dev_get_stats+0x19/0x1b > > [ 24.982989] [] ? dev_seq_show+0x21/0x80 > > [ 24.982989] [] ? seq_read+0x1f2/0x2d8 > > [ 24.982989] [] ? seq_read+0x0/0x2d8 > > [ 24.982989] [] ? proc_reg_read+0x60/0x74 > > [ 24.982989] [] ? proc_reg_read+0x0/0x74 > > [ 24.982989] [] ? vfs_read+0x6d/0x91 > > [ 24.982989] [] ? sys_read+0x3b/0x5d > > [ 24.982989] [] ? sysenter_do_call+0x12/0x31 > > [ 24.982989] Code: 66 c0 56 c0 c3 55 83 c9 ff 89 e5 57 31 ff 56 31 f6 53 83 ec 04 8d 58 48 8b 80 20 03 00 00 89 45 f0 eb 0d 8b 45 f0 f7 d0 8b 04 88 <03> 78 04 03 30 89 c8 ba 50 96 79 c0 e8 72 a3 f7 ff 83 f8 1f 89 > > [ 24.982989] EIP: [] loopback_get_stats+0x26/0x51 SS:ESP 0068:de7b9eec > > [ 25.029067] ---[ end trace a599d5330cca1e8d ]--- > > At a guess I'd say that local variable `stats' in loopback_get_stats() > is null. > > That code was recently changed in linux-next: > > commit c02373bf2759dd210dc8c72c9c9b4a8f1c279cac > Author: Stephen Hemminger > Date: Wed Nov 19 21:46:18 2008 -0800 > > netdev: convert loopback to net_device_ops > > First device to convert over is the loopback device. > > Signed-off-by: Stephen Hemminger > Signed-off-by: David S. Miller > > but it's a bit hard to see how that change could cause the crash which > you observed. Could be that some other code is stomping on per-cpu variables?