From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262017AbUC1RAV (ORCPT ); Sun, 28 Mar 2004 12:00:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262022AbUC1RAV (ORCPT ); Sun, 28 Mar 2004 12:00:21 -0500 Received: from mail.parknet.co.jp ([210.171.160.6]:18953 "EHLO mail.parknet.co.jp") by vger.kernel.org with ESMTP id S262017AbUC1RAQ (ORCPT ); Sun, 28 Mar 2004 12:00:16 -0500 To: "Andrew Reiter" Cc: Subject: Re: NULL pointer in proc_pid_stat -- oops. References: <8758F8D58219684FAB0239EE8967048A4A7D5E@calculon.preventsys.com> From: OGAWA Hirofumi Date: Mon, 29 Mar 2004 02:00:03 +0900 In-Reply-To: <8758F8D58219684FAB0239EE8967048A4A7D5E@calculon.preventsys.com> Message-ID: <873c7sewks.fsf@devron.myhome.or.jp> User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org "Andrew Reiter" writes: > 0x000004d4 : test %ecx,%ecx > 0x000004d6 : je 0x510 > 0x000004d8 : mov 0x98(%ecx),%eax > 0x000004de : mov %eax,0x20(%esp,1) > 0x000004e2 : mov 0x4(%ecx),%edx > 0x000004e5 : movswl 0x64(%edx),%eax > 0x000004e9 : movswl 0x66(%edx),%edx > 0x000004ed : shl $0x14,%eax > 0x000004f0 : or %edx,%eax > 0x000004f2 : add 0x8(%ecx),%eax > > And from the oops trace output (that is attached), we can see that %edx > is 0x0; so we can easily see here why we're crashing at least. After > examining the C source, I see that we're dying in the call to > task_name() (inline) from proc_pid_stat(). Looks like this problem is same with BSD acct Oops. if (task->tty) { tty_pgrp = task->tty->pgrp; tty_nr = new_encode_dev(tty_devnum(task->tty)); } Some place doesn't take the any lock for ->tty. I think we need to take the lock for ->tty. -- OGAWA Hirofumi