From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756606Ab0JRV4c (ORCPT ); Mon, 18 Oct 2010 17:56:32 -0400 Received: from www.tglx.de ([62.245.132.106]:55051 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755064Ab0JRV4b (ORCPT ); Mon, 18 Oct 2010 17:56:31 -0400 Date: Mon, 18 Oct 2010 23:55:44 +0200 (CEST) From: Thomas Gleixner To: Andrew Morton cc: Mel Gorman , pacman@kosh.dhis.org, linux-mm@kvack.org, LKML , linuxppc-dev@lists.ozlabs.org, Helmut Grohne Subject: Re: PROBLEM: memory corrupting bug, bisected to 6dda9d55 In-Reply-To: <20101018123750.ef7d6d48.akpm@linux-foundation.org> Message-ID: References: <20101013144044.GS30667@csn.ul.ie> <20101013175205.21187.qmail@kosh.dhis.org> <20101018113331.GB30667@csn.ul.ie> <20101018123750.ef7d6d48.akpm@linux-foundation.org> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 18 Oct 2010, Andrew Morton wrote: > On Mon, 18 Oct 2010 12:33:31 +0100 > Mel Gorman wrote: > > > A bit but I still don't know why it would cause corruption. Maybe this is still > > a caching issue but the difference in timing between list_add and list_add_tail > > is enough to hide the bug. It's also possible there are some registers > > ioremapped after the memmap array and reading them is causing some > > problem. > > > > Andrew, what is the right thing to do here? We could flail around looking > > for explanations as to why the bug causes a user buffer corruption but never > > get an answer or do we go with this patch, preferably before 2.6.36 releases? > > Well, you've spotted a bug so I'd say we fix it asap. > > It's a bit of a shame that we lose the only known way of reproducing a > different bug, but presumably that will come back and bite someone else > one day, and we'll fix it then :( I might be completely one off as usual, but this thing reminds me of a bug I stared at yesterday night: http://permalink.gmane.org/gmane.linux.kernel/1049605 Reporter Cc'ed Thanks, tglx