Re: [PATCH 1/1] KVM: Fix potentially recursively get kvm lock

Chris Wright
2009-05-22T15:36:42Z

* Alex Williamson (alex.williamson@hp.com) wrote:
> On Fri, 2009-05-22 at 08:06 -0700, Chris Wright wrote:
> > * Alex Williamson (alex.williamson@hp.com) wrote:
> > > On Tue, 2009-05-12 at 19:09 -0300, Marcelo Tosatti wrote:
> > > > KVM: workaround workqueue / deassign_host_irq deadlock
> > > >
> > > > I think I'm running into the following deadlock in the kvm kernel module
> > > > when trying to use device assignment:
> > > >
> > > > CPU A CPU B
> > > > kvm_vm_ioctl_deassign_dev_irq()
> > > > mutex_lock(&kvm->lock); worker_thread()
> > > > -> kvm_deassign_irq() ->
> > > > kvm_assigned_dev_interrupt_work_handler()
> > > > -> deassign_host_irq() mutex_lock(&kvm->lock);
> > > > -> cancel_work_sync() [blocked]
> > > >
> > > > Workaround the issue by dropping kvm->lock for cancel_work_sync().
> >
> > Is this still pending?
>
> I haven't seen this particular workaround make it into a tree, however
> Marcelo has been working on a set of patches to properly fix this. Most
> recent version was sent on 5/20.

Great, thanks.
-chris