Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754046AbYJ0Vap (ORCPT ); Mon, 27 Oct 2008 17:30:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752515AbYJ0VaP (ORCPT ); Mon, 27 Oct 2008 17:30:15 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:40826 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752334AbYJ0VaM (ORCPT ); Mon, 27 Oct 2008 17:30:12 -0400 Date: Mon, 27 Oct 2008 14:30:06 -0700 From: Mike Anderson To: Tejun Heo Cc: James Bottomley , Jens Axboe , linux-scsi , IDE/ATA development list , Linux Kernel Subject: Re: Timeout regression introduced by 242f9dcb8ba6f68fcd217a119a7648a4f69290e9 Message-ID: <20081027213006.GB17946@linux.vnet.ibm.com> References: <49043C7C.8050207@kernel.org> <1225034105.3958.4.camel@localhost.localdomain> <49051EA4.3040403@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49051EA4.3040403@kernel.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1755 Lines: 39 Tejun Heo wrote: > James Bottomley wrote: > > On Sun, 2008-10-26 at 18:46 +0900, Tejun Heo wrote: > >> Hello, Jens. > >> > >> Commit 242f9dcb8ba6f68fcd217a119a7648a4f69290e9 introduces a strange > >> regression for libata. The second timeout gives puts different > >> pointer from the issued command onto eh_cmd_q breaking libata EH > >> command matching which triggers WARN_ON() in ata_eh_finish() and hangs > >> command processing or causes oops later depending on circumstances. > >> > >> Here are logs with induced timeouts (patch attached). In commit > >> 242f9dcb8, the XXX messages for the second timeout shows different > >> scsi_cmd pointers for eh_cmd_q and qc->scmd which is initialized by > >> ata_scsi_qc_new() during command translation. > > > > I can't see a way we could be getting a different command passed in from > > the actual one, since the only way to lose the command from the request > > is to go through the command completion routines which free it (and end > > the request). > > I have no idea either. It's something in the timeout logic because on > the issue path the scmd pointer is identical but on tiemout pointer > for another scmd is queued on eh_cmd_q, which doesn't make much sense. > I was trying to recreate this error using ata_ram wth v2.6.28-rc2. Currently I am not able to see this error on timeout recovery using this setup. Does IO load (or other factors) effect the error being seen? -andmike -- Michael Anderson andmike@linux.vnet.ibm.com -- 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/