On Thu, Apr 13, 2017 at 09:45:49AM -0500, Eric Blake wrote: > 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 avoid > >>>> such a > >>>> hang. > >>> > >>> I'd argue for including a fix for 2.9, since this is both a regression, > >>> and > >>> a hard lock without possible recovery short of restarting the QEMU > >>> process. > >> > >> It is a bit of a corner case (and jobs on I/O thread are relatively rare > >> too), so maybe it's not worth delaying 2.9. It has been delayed already > >> quite a bit. Another reason I think I prefer to wait is to ensure that > >> we have an entry in qemu-iotests to avoid the future regression. > > > > I also think this does not require delaying the release: > > > > 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. > > > > 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. >
No - if the guest initiates a reboot itself, we still end up deadlocked. -Jeff
