From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753894AbZHMJWy (ORCPT ); Thu, 13 Aug 2009 05:22:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753875AbZHMJWx (ORCPT ); Thu, 13 Aug 2009 05:22:53 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:58574 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753871AbZHMJWx (ORCPT ); Thu, 13 Aug 2009 05:22:53 -0400 From: Juergen Beisert Organization: Pengutronix - Linux Solutions for Science and Industry To: ben-linux@fluff.org Date: Thu, 13 Aug 2009 11:22:39 +0200 User-Agent: KMail/1.9.9 Cc: linux-kernel@vger.kernel.org, Mel Gorman , Arnaud Faucher , linux-arm-kernel@lists.arm.linux.org.uk, linux-hotplug@vger.kernel.org References: <200908111830.03224.jbe@pengutronix.de> <1250102430.4912.4.camel@green> <20090813083910.GA27006@csn.ul.ie> In-Reply-To: <20090813083910.GA27006@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200908131122.40423.jbe@pengutronix.de> X-SA-Exim-Connect-IP: 92.198.50.58 X-SA-Exim-Mail-From: jbe@pengutronix.de Subject: Re: Patch "page-allocator: preserve PFN ordering when __GFP_COLD is set" fails on my system X-SA-Exim-Version: 4.2.1 (built Tue, 09 Jan 2007 17:23:22 +0000) X-SA-Exim-Scanned: Yes (on metis.ext.pengutronix.de) X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Donnerstag, 13. August 2009, Mel Gorman wrote: > On Wed, Aug 12, 2009 at 02:40:30PM -0400, Arnaud Faucher wrote: > > I have a rather similar problem on a driver that I try to keep > > up-to-date with recent kernel versions > > (http://code.ximeta.com/trac-ndas/ticket/1110#comment:30). The NDAS > > hardware is an ethernet-enabled disk controller on one chip, kind of a > > cheap iSCSI. > > > > In my case there is no oops: the symptoms are that the read blocks seem > > to be swapped or full of garbage. > > > > After investigation in the NDAS code, the bug triggers when the driver > > tries to merge adjacent requests before sending them to the controller. > > I had to disable this merge in order to restore normal behavior, at the > > expense of a reduced efficiency. > > That is a very interesting point and one I hadn't considered. The point > of the patch was to help drivers that merge adjacent requests if they > happen to be physically contiguous. The reported bug that led to the > patch was a regression of memory not being physically contiguous and > requests not being merged. > > > > After this oops, system startup continues. Then the next oops occurs: > > > > > > This one is new, since I try to mount the connected SD card. > > > > Mel's buffer overrun theory seems to apply in the NDAS driver case, > > where the original requests adjacency test seems faulty. > > > > May it also be the cause of the SD mounting crash ? > > It's a possibility. If it's not an overrun, it's possible that the > automatic merging code is buggy as well. > > Juergen, is the disk controller on your machine capable of merging > requests? If so, can you disable it and see if the bug still occurs > please? Hmmm, hard to say. Maybe the author of this driver can say more. @Ben: MMC/SD/SDHC driver for the s3c2440-CPU. Can you answer Mel's question? Regards, Juergen -- Pengutronix e.K. | Juergen Beisert | Linux Solutions for Science and Industry | Phone: +49-8766-939 228 | Vertretung Sued/Muenchen, Germany | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de/ |