From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52087) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XMxJc-0004VC-Cy for qemu-devel@nongnu.org; Thu, 28 Aug 2014 06:52:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XMxJT-0007i9-Bz for qemu-devel@nongnu.org; Thu, 28 Aug 2014 06:52:28 -0400 Received: from mail-wi0-x22b.google.com ([2a00:1450:400c:c05::22b]:35661) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XMxJT-0007i5-3g for qemu-devel@nongnu.org; Thu, 28 Aug 2014 06:52:19 -0400 Received: by mail-wi0-f171.google.com with SMTP id hi2so7250323wib.4 for ; Thu, 28 Aug 2014 03:52:18 -0700 (PDT) Date: Thu, 28 Aug 2014 11:52:15 +0100 From: Stefan Hajnoczi Message-ID: <20140828105215.GF26741@stefanha-thinkpad.redhat.com> References: <20140820203746.5581.233.malonedeb@gac.canonical.com> <20140820203746.5581.233.malonedeb@gac.canonical.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="eDB11BtaWSyaBkpc" Content-Disposition: inline In-Reply-To: <20140820203746.5581.233.malonedeb@gac.canonical.com> Subject: Re: [Qemu-devel] [Bug 1359394] [NEW] virtio block device hangs after "virtio_blk virtio3: requests:id 0 is not a head!" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Bug 1359394 <1359394@bugs.launchpad.net> Cc: qemu-devel@nongnu.org --eDB11BtaWSyaBkpc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Aug 20, 2014 at 08:37:46PM -0000, Slava Pestov wrote: > The virtual machine is running block layer workloads, interrupted by > unclean reboots (echo b > /proc/sysrq-trigger). Kernel version is 3.14. >=20 > Sometimes, I get this message on boot: >=20 > "virtio_blk virtio3: requests:id 0 is not a head!" >=20 > Then, I/O to the virtio block devices just hangs. >=20 > Unfortunately I don't have a test case and this is kind of hard to > reproduce, but it seems related to having I/O in flight when the kernel > is forced to reboot. Hi Slava, Sounds like the virtio device was not reset properly. The guest kernel is looking for completed responses from the host. The host has indicated that descriptor 0 is the next completed response but the guest does not remember having submitted it. Do you have a kernel stack trace when this was encountered? Stefan --eDB11BtaWSyaBkpc Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJT/wnfAAoJEJykq7OBq3PI/JoH/RKs5aROVIw2ndd8t3K3gR39 qW/l6k5qTQTprXKuV/oNsjpYZDQ/o+NzUOZ5xaHcpaod3nYAj+X+ZvWmmb7k6ULT 11hd9LHRAp49OlyZhoa/p055PRblDzvMyNMuqAgfCas+mmfZWmklHdTU1ZtUTCOp tgu/M/V9l+J6UTm1r3n7s7voJjk/BHSBN8fAkfJgar42lz1A5OP5EyOOowyVqB7c nRjZD33gCHwV9q1aahxIkFSeox1vnLzbwldezPR9AJzjCpjezjB/l5ro1WZBD7MO dvvjzAHx079eLipGs4+wggPwVyOhJAa5DG0HnjJlNc6T/59QyahU0SgD4QBo5WI= =CJOw -----END PGP SIGNATURE----- --eDB11BtaWSyaBkpc--