From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39360) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cyg0d-0000NR-0h for qemu-devel@nongnu.org; Thu, 13 Apr 2017 10:46:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cyg0b-0003UJ-NA for qemu-devel@nongnu.org; Thu, 13 Apr 2017 10:46:07 -0400 References: <20170412204641.GA15762@localhost.localdomain> <20170412222251.GB15762@localhost.localdomain> <20170412235420.GB8607@lemon> <20170413011109.GC15762@localhost.localdomain> <20170413143959.GE13387@stefanha-x1.localdomain> From: Eric Blake Message-ID: <53e4fffa-2e35-daff-0bbc-13d8992c9e90@redhat.com> Date: Thu, 13 Apr 2017 09:45:49 -0500 MIME-Version: 1.0 In-Reply-To: <20170413143959.GE13387@stefanha-x1.localdomain> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Vsa7B2a0G041knCb1CWpfSQfUtGcMhNgA" Subject: Re: [Qemu-devel] Regression from 2.8: stuck in bdrv_drain() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , Paolo Bonzini Cc: kwolf@redhat.com, peter.maydell@linaro.org, Fam Zheng , qemu-block@nongnu.org, Jeff Cody , qemu-devel@nongnu.org, John Snow This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Vsa7B2a0G041knCb1CWpfSQfUtGcMhNgA From: Eric Blake To: Stefan Hajnoczi , Paolo Bonzini Cc: kwolf@redhat.com, peter.maydell@linaro.org, Fam Zheng , qemu-block@nongnu.org, Jeff Cody , qemu-devel@nongnu.org, John Snow Message-ID: <53e4fffa-2e35-daff-0bbc-13d8992c9e90@redhat.com> Subject: Re: [Qemu-devel] Regression from 2.8: stuck in bdrv_drain() References: <20170412204641.GA15762@localhost.localdomain> <20170412222251.GB15762@localhost.localdomain> <20170412235420.GB8607@lemon> <20170413011109.GC15762@localhost.localdomain> <20170413143959.GE13387@stefanha-x1.localdomain> In-Reply-To: <20170413143959.GE13387@stefanha-x1.localdomain> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 04/13/2017 09:39 AM, Stefan Hajnoczi wrote: > On Thu, Apr 13, 2017 at 01:45:55PM +0800, Paolo Bonzini wrote: >> >> >> On 13/04/2017 09:11, Jeff Cody wrote: >>>> It didn't make it into 2.9-rc4 because of limited time. :( >>>> >>>> Looks like there is no -rc5, we'll have to document this as a known = issue. >>>> Users should "block-job-complete/cancel" as soon as possible to avoi= d such a >>>> hang. >>> >>> I'd argue for including a fix for 2.9, since this is both a regressio= n, and >>> a hard lock without possible recovery short of restarting the QEMU pr= ocess. >> >> It is a bit of a corner case (and jobs on I/O thread are relatively ra= re >> too), so maybe it's not worth delaying 2.9. It has been delayed alrea= dy >> quite a bit. Another reason I think I prefer to wait is to ensure tha= t >> we have an entry in qemu-iotests to avoid the future regression. >=20 > I also think this does not require delaying the release: >=20 > 1. It needs to be marked as a known issue in the release notes. > 2. Let's roll the 2.9.1 stable release within a month of 2.9.0. >=20 > If both conditions are met then very few end users will be exposed to > the problem. I hope libvirt will create IOThreads by default soon but > for the time being it is not a widely used configuration. Also, is it something that can be avoided by not doing a system_reset while a block job is still running? Libvirt can be taught to block reset while a job has still not been finished, if needs be. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org --Vsa7B2a0G041knCb1CWpfSQfUtGcMhNgA Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJY748dAAoJEKeha0olJ0NqlKgIAJ5hUE4j43WJ2PgIfTxzGw8C 58vgeee/qpkuB9vfLXNf7zeYFXndadjqGSuCweGV9jCxEfdOEQiCmVjiQ2Acxx5+ MlwMlygpBPUo8pkU088WE8Q/syXrOFmnIlNDdJ8Gyot+4XpEaCuRb5pFGJ1KvNp5 /XRY8Ypg3UqNRZk0bvoj3Z2NLaNGb+huYqlWCybRiD/lnMeWmv14b+y8Sff6zMbg LtwvHwa/UIlqOICfK8u59rEk8fA4hZ7hZnQlJ++rTSLZ5S7ZPSzNeYk0SEnGOmos 3npBNYftzDaSI2hhuiz1RvbsOc4sdK/LROG1+lJDYuhgubzlxzZcnk5lRMBuz2A= =Gbw0 -----END PGP SIGNATURE----- --Vsa7B2a0G041knCb1CWpfSQfUtGcMhNgA--