Re: virtio_balloon regression in 5.19-rc3

[Jason Wang <jasowang@redhat.com>]

On Tue, Jun 21, 2022 at 5:24 PM David Hildenbrand <david@redhat.com> wrote:
>
> On 20.06.22 20:49, Ben Hutchings wrote:
> > I've tested a 5.19-rc3 kernel on top of QEMU/KVM with machine type
> > pc-q35-5.2.  It has a virtio balloon device defined in libvirt as:
> >
> >     <memballoon model="virtio">
> >       <address type="pci" domain="0x0000" bus="0x05" slot="0x00" function="0x0"/>
> >     </memballoon>
> >
> > but the virtio_balloon driver fails to bind to it:
> >
> >     virtio_balloon virtio4: init_vqs: add stat_vq failed
> >     virtio_balloon: probe of virtio4 failed with error -5
> >
>
> Hmm, I don't see any recent changes to drivers/virtio/virtio_balloon.c
>
> virtqueue_add_outbuf() fails with -EIO if I'm not wrong. That's the
> first call of virtqueue_add_outbuf() when virtio_balloon initializes.
>
>
> Maybe something in generic virtio code changed?

Yes, we introduced the IRQ hardening. That could be the root cause and
we've received lots of reports so we decide to disable it by default.

Ben, could you please try this patch: (and make sure
CONFIG_VIRTIO_HARDEN_NOTIFICATION is not set)

https://lore.kernel.org/lkml/20220620024158.2505-1-jasowang@redhat.com/T/

Thanks

>
> --
> Thanks,
>
> David / dhildenb
>