From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id DB41C6B0087 for ; Mon, 11 Oct 2010 17:02:07 -0400 (EDT) Date: Mon, 11 Oct 2010 14:00:39 -0700 From: Andrew Morton Subject: Re: PROBLEM: memory corrupting bug, bisected to 6dda9d55 Message-Id: <20101011140039.15a2c78d.akpm@linux-foundation.org> In-Reply-To: <20101011143022.GD30667@csn.ul.ie> References: <20101009095718.1775.qmail@kosh.dhis.org> <20101011143022.GD30667@csn.ul.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: pacman@kosh.dhis.org, linux-mm@kvack.org, Christoph Lameter , KOSAKI Motohiro , Yinghai Lu , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org List-ID: (cc linuxppc-dev@lists.ozlabs.org) On Mon, 11 Oct 2010 15:30:22 +0100 Mel Gorman wrote: > On Sat, Oct 09, 2010 at 04:57:18AM -0500, pacman@kosh.dhis.org wrote: > > (What a big Cc: list... scripts/get_maintainer.pl made me do it.) > > > > This will be a long story with a weak conclusion, sorry about that, but it's > > been a long bug-hunt. > > > > With recent kernels I've seen a bug that appears to corrupt random 4-byte > > chunks of memory. It's not easy to reproduce. It seems to happen only once > > per boot, pretty quickly after userspace has gotten started, and sometimes it > > doesn't happen at all. > > > > A corruption of 4 bytes could be consistent with a pointer value being > written to an incorrect location. It's corruption of user memory, which is unusual. I'd be wondering if there was a pre-existing bug which 6dda9d55bf545013597 has exposed - previously the corruption was hitting something harmless. Something like a missed CPU cache writeback or invalidate operation. How sensitive/vulnerable is PPC32 to such things? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org