On 7/17/26 02:22, Link Lin wrote: > During PM freeze (e.g. S3 suspend or S4 hibernation), device drivers like > virtio_balloon reset their underlying virtio devices and delete their > virtqueues via vdev->config->del_vqs(). > > However, page reporting work (page_reporting_process) was scheduled on > the global system_wq. Because system_wq lacks the WQ_FREEZABLE flag, the > PM freezer skips it, leaving page_reporting_process active during > suspend. If pages are freed into the buddy allocator while suspending, > page reporting invokes virtballoon_free_page_report() on deleted > virtqueues: > > [ 196.795226] general protection fault, probably for non-canonical > address 0xaa1436fe70dae6df: 0000 [#1] SMP NOPTI > [ 196.825967] Workqueue: events page_reporting_process > [ 196.831038] RIP: 0010:virtqueue_add_split+0x233/0x4c0 [virtio_ring] > [ 196.927073] virtballoon_free_page_report+0x3a/0xe0 [virtio_balloon] > [ 196.946943] page_reporting_process+0x370/0x4f0 > > Fix this by switching page reporting work to system_freezable_wq. This > ensures that the PM freezer pauses page_reporting_process before device > drivers destroy their reporting virtqueues. > > This aligns with the driver's existing design. The comment in > virtballoon_freeze() states: > /* > * The workqueue is already frozen by the PM core before this > * function is called. > */ > > Suggested-by: David Hildenbrand <[email protected]> > Suggested-by: Michael S. Tsirkin <[email protected]> > Acked-by: David Rientjes <[email protected]> > Fixes: 924a663f75e2 ("virtio-balloon: Reporting free page reservations") > Cc: [email protected] > Signed-off-by: Link Lin <[email protected]>
Acked-by: David Hildenbrand (Arm) <[email protected]> -- Cheers, David
