From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264412AbUEMTIh (ORCPT ); Thu, 13 May 2004 15:08:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264422AbUEMTIg (ORCPT ); Thu, 13 May 2004 15:08:36 -0400 Received: from ipcop.bitmover.com ([192.132.92.15]:22755 "EHLO work.bitmover.com") by vger.kernel.org with ESMTP id S264412AbUEMTIf (ORCPT ); Thu, 13 May 2004 15:08:35 -0400 Date: Thu, 13 May 2004 12:08:33 -0700 From: Andy Isaacson To: linux-kernel@vger.kernel.org Subject: 1352 NUL bytes at the end of a page? Message-ID: <20040513190833.GH17965@bitmover.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org We've got a user who's reporting BK problems which we've traced down to the fact that his s.ChangeSet file has a hole, filled with '\0' bytes, that's so far always 1352 bytes long, and the end is page-aligned. (In fact, the two cases we've seen so far have been 8k-aligned.) The correct file data picks up again after the hole. bk is writing the data using stdio in a child process (fork, exec, wait), then mmaping the result. The corruption is persistent; he sent us the s.ChangeSet file and there it was (not a cache or buffering problem, therefore). 2.6.6-bk (current head of tree from whenever he built), UP PIII, symptom observed on both ext3 and reiserfs. (However, we've explicitly verified the hole only on reiser.) The problem is intermittent, having happened "several" times over the last few months, and doesn't appear to be tied to any particular kernel version. To me, this looks awfully close to an Ethernet frame size... but that's just a wild guess. And I don't think he's running Ethernet (still waiting for dmesg and .config). I've asked for more info, memtest86, and will attempt to reproduce it on another box. Does anyone have insight into this peculiar problem? -andy