Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 25 Apr 2001 21:16:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 25 Apr 2001 21:16:45 -0400 Received: from horus.its.uow.edu.au ([130.130.68.25]:13799 "EHLO horus.its.uow.edu.au") by vger.kernel.org with ESMTP id ; Wed, 25 Apr 2001 21:16:31 -0400 Message-ID: <3AE77578.42A62EA6@uow.edu.au> Date: Wed, 25 Apr 2001 18:10:16 -0700 From: Andrew Morton X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.3-ac13 i686) X-Accept-Language: en MIME-Version: 1.0 To: Tobias Ringstrom CC: Kernel Mailing List Subject: Re: Weird problem with 2.4.4-pre6 In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Tobias Ringstrom wrote: > > Yesterday, I was running tcpdump, paging the output with less. All of a > sudden, less started to dump core (SIGSEGV). I could not even start less > by itself: > > > less > > without it getting a SIGSEGV, and in fact no user could run less without > getting a SIGSEGV, but it did work perfectly a few minutes earlier. This > morning, I tried to run less again, and now it was working! No core > dumps! > > How can this happen? Something overwriting the page/buffer cache? Yes. Something scribbled on the pagecache, most likely. If this happens, take a copy of the offending binary and all its shared libraries - simply copy them into a temp directory. The corrupted version will be written to disk, from the pagecache. Make sure you keep a copy of the offending vmlinux as well for looking things up in. Then reboot and start diffing things; the differences can provide clues. If the diffs show single-bit errors then it's a RAM problem. If the diffs look like pointers into kernel space then look 'em up in vmlinux and shout loudly. etc. - - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/