From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261511AbVACRZH (ORCPT ); Mon, 3 Jan 2005 12:25:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261508AbVACRWu (ORCPT ); Mon, 3 Jan 2005 12:22:50 -0500 Received: from ns1.digitalpath.net ([65.164.104.5]:25495 "HELO mail.digitalpath.net") by vger.kernel.org with SMTP id S261511AbVACRWb (ORCPT ); Mon, 3 Jan 2005 12:22:31 -0500 Date: Mon, 3 Jan 2005 09:22:22 -0800 From: Ray Van Dolson To: Matt Domsch Cc: linux-kernel@vger.kernel.org Subject: Re: Unable to handle kernel NULL pointer dereference at virtual address 00000000 Message-ID: <20050103172222.GA13804@digitalpath.net> Mail-Followup-To: Matt Domsch , linux-kernel@vger.kernel.org References: <20041215013228.GA3390@digitalpath.net> <20041215162943.GB31494@lists.us.dell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041215162943.GB31494@lists.us.dell.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 15, 2004 at 10:29:43AM -0600, Matt Domsch wrote: > > ksymoops output of problem: > > Unable to handle kernel NULL pointer dereference > > 00000000 > > *pde = 00000000 > > Oops: 0000 [#1] > > CPU: 2 > > EIP: 0060:[<00000000>] Not tainted VLI > > Using defaults from ksymoops -t elf32-i386 -a i386 > > EFLAGS: 00010286 (2.6.9) > > eax: ed13b000 ebx: d1d0a000 ecx: c029e9de edx: f795ef40 > > esi: d1d0a000 edi: 00000000 ebp: e2f30080 esp: d2b0dea0 > > ds: 007b es: 007b ss: 0068 > > Stack: c02a205a ed13b000 00000000 c02a122c d1d0a000 13208a2e c040956f > > d1d0a000 d1d0a00c e2f30080 00000000 c029cda9 d1d0a000 e2f30080 00000000 > > c01552cd e2f30080 00000010 00000004 00000004 c0166aa0 e2f30080 00000000 > > 00000000 > > Call Trace: [] pty_chars_in_buffer+0x2c/0x49 [] > > normal_poll+0xed/0x150 [] schedule_timeout+0x75/0xbf > > [] tty_poll+0xa0/0xb0 [] fget+0x49/0x5e [] > > do_select+0x269/0x2c6 [] __pollwait+0x0/0xc7 [] > > sys_select+0x2b3/0x4c6 [] sysenter_past_esp+0x52/0x71 > > Code: Bad EIP value. > It looks like pty_chars_in_buffer() dereferenced a NULL function > pointer, but I don't see how that can be, the one deference is tested > for NULL before doing so. > > I can't rule out the ppp_mppe code, but I haven't seen this crash > before myself. Does this happen on simlar systems that aren't running poptop? > > Thanks, > Matt Yet another follow-up on this. After completely disabling SMP/Hyperthreading on these systems, we have had zero NULL pointer dereferences. Obviously can't say for sure that this points to problems with the MPPE module--the only true test would be to allow our customers to connect without MPPE and reenable SMP/HT. Obviously not an option in a live environment. :) Guess we just won't be using SMP/HT on our busier systems! Ray