virtio_balloon: quiesce balloon work before device shutdown

Browse source

Commit 8bd2fa086a ("virtio: break and reset virtio devices on
device_shutdown()") added a generic virtio bus .shutdown handler that
breaks and resets every virtio device during device_shutdown(), i.e. on
reboot and kexec.

virtio_balloon provides no .shutdown of its own, so that generic path
runs while the balloon's asynchronous work is still armed. Once the
device has been broken, virtqueue_add_inbuf() in
virtballoon_free_page_report() returns -EIO and trips its
WARN_ON_ONCE(). On a kernel booted with panic_on_warn that turns an
ordinary reboot, for example a kexec based upgrade, into a fatal panic
in the middle of device_shutdown(), so the machine never reaches the
new kernel.

Relaxing that single WARN_ON_ONCE() would only hide the symptom: the
inflate/deflate and OOM paths do not warn, they call
wait_event(vb->acked, ...) and would instead block forever on a broken
queue that can no longer complete. The device has to be quiesced, not
just kept quiet.

Add a .shutdown handler that quiesces the balloon via the shared
virtballoon_quiesce() helper while the device is still alive, and only
then breaks and resets it via virtio_device_shutdown(). Unlike
virtballoon_remove() the balloon workqueue is not destroyed, as shutdown
does not free the device and cancel_work_sync() together with stop_update
already prevent any further work from being queued.

Fixes: 8bd2fa086a ("virtio: break and reset virtio devices on device_shutdown()")
Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260624140846.2616797-4-den@openvz.org>

...

This commit is contained in:

Denis V. Lunev 2026-06-24 16:08:45 +02:00 • committed by Michael S. Tsirkin

parent 29536a923a

commit 7e17eef046

1 changed files with 7 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

7

drivers/virtio/virtio_balloon.c

View file