From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755234Ab2EBOZH (ORCPT ); Wed, 2 May 2012 10:25:07 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:50811 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754360Ab2EBOZF (ORCPT ); Wed, 2 May 2012 10:25:05 -0400 Message-ID: <4FA143BC.2010702@canonical.com> Date: Wed, 02 May 2012 16:25:00 +0200 From: Stefan Bader User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120410 Thunderbird/11.0.1 MIME-Version: 1.0 To: linux-scsi@vger.kernel.org, Linux Kernel Mailing List CC: Matthew Wilcox , Stefan Bader Subject: Kernel oops in sym_int_sir X-Enigmail-Version: 1.4 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="------------enig8EC0A656348579D86C92CEE4" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig8EC0A656348579D86C92CEE4 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable While looking at a bug report [1] I found that the immediate cause of the= crash was in that specific case the reference cp->cmd for a printk: /* * The device didn't switch to MSG IN phase after * having reselected the initiator. */ case SIR_RESEL_NO_MSG_IN: scmd_printk(KERN_WARNING, cp->cmd, "No MSG IN phase after reselection\n"); goto out_stuck; Unfortunately cp (that is returned by sym_ccb_from_dsa()) is NULL. This p= robably is as old as 2.6.24 when this patch added the scmd_printk: commit 3fb364e089e05c35ead55a08d56d3004193681f6 Author: Matthew Wilcox Date: Fri Oct 5 15:55:10 2007 -0400 [SCSI] sym53c8xx: Use scmd_printk where appropriate A quick research looks like it might be other cases where this happened[2= ]. Maybe more often (or solely?) when running in a VM (KVM). I even found so= me post that looks like it tries to fix just this problem[3]. However without more knowledge about that driver it could also be a probl= em in the hardware emulation so that normally cp =3D=3D NULL should never happe= n. Or it might be that the emulation is just running sufficiently "different" to c= ause races to happen which never would be observed on real hardware. Would [3] still make sense? Thanks, Stefan [1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/992328 [2] http://www.mail-archive.com/kvm@vger.kernel.org/msg08927.html [3] https://lkml.org/lkml/2010/11/18/495 --------------enig8EC0A656348579D86C92CEE4 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQIcBAEBCgAGBQJPoUO9AAoJEOhnXe7L7s6jFtAQAM3ffrcFuZkV18vOKXUGFXir 8vCSDz6CI+i7cqskXp3DcD50OxvU8snChHRF8f7vqkekia0m5OBMvdEN8sS9g6la UYZg9ABoYhoMtmrcaa5UlJEbA8clHmQX4iIEfNrlDpEKFFpj2TqXoWmtzZwvWh+v vfj1pAoRT195W4GqqhNCcF68OdO7j7F6u9hgqkiNXA2YSrIv0Y0LmC1b/nOUsrDf dPDr3mQQZ6oMyImUJYK09ENP1X516Rfo5SI+BBfeb3oXOPHiJU0rkcXyF9Qg4hcU McKBjNlypIbjz+Fqdyl7BbA0BPgNiMvHDJVqBs16Z2InTX0f1zHxiTo/GeY3MTC+ DdjZYo304KW/3xN6v0eYGu7JWK/zAWEEx9Ko4QoAogspW/O9ZhgKk+rkD0M8/x0T k6K+FFSetKDWXwYC/o8kUA7RpTCpVaJNl5uWtKrOD/gE4IP2GmSvomLbAHEZ3Bah uAezJGhNBrInDa28XnsZHDm1ijtrKkyb35TeLRi+YZnzGsHRgcA1GfIuQeki/kuZ u9q+LV4o63mo8/lvn/MWN8eQVqVMiWnCABjHotu3tJfM8SVTMyzbQ2f9iHZqCyvp kKlPia0oixeC9rTNd6oPFIVrtrmz134qm9bRDRcPpM5DlQW1eN1V71pfbdDoBkuM iicmAhrTe4HPMRvnBb8C =M68O -----END PGP SIGNATURE----- --------------enig8EC0A656348579D86C92CEE4--