On Fri, Sep 11, 2026 at 12:31 AM Cong Zhang <[email protected]> wrote: > > Replace blk_mq_quiesce_queue_nowait() with blk_mq_quiesce_queue() in > virtblk_freeze_priv(). > > Keep the existing freeze and unfreeze order. The synchronous call waits > for dispatch code that was already running. The queue remains quiesced > until virtblk_restore_priv() calls blk_mq_unquiesce_queue(). > > Fixes: 7678abee0867 ("virtio-blk: don't keep queue frozen during system > suspend") >
Do we need this for -stable? > Signed-off-by: Cong Zhang <[email protected]> > --- > blk_mq_run_work_fn() can call blk_mq_sched_dispatch_requests() through > blk_mq_run_dispatch_ops(). The dispatcher checks QUEUE_FLAG_QUIESCED > while the flag is clear. It can then be preempted before it gets a > request. At that time, it has no queue usage reference, so > blk_mq_freeze_queue() does not wait for it. > > virtblk_freeze_priv() then calls blk_mq_quiesce_queue_nowait() and > blk_mq_unfreeze_queue(). A new request can enter the queue. The old > dispatcher can run again, use its old flag check, get the new request, > and call virtio_queue_rq(). At the same time, virtblk_freeze_priv() can > reset the device, delete the virtqueues, and free vblk->vqs. The old > dispatcher can then use a deleted virtqueue or a NULL vblk->vqs, and the > kernel can crash. > --- > drivers/block/virtio_blk.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index 32bf3ba07a9d..7a570591e040 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -1595,7 +1595,7 @@ static int virtblk_freeze_priv(struct virtio_device > *vdev) > > /* Ensure no requests in virtqueues before deleting vqs. */ > memflags = blk_mq_freeze_queue(q); > - blk_mq_quiesce_queue_nowait(q); > + blk_mq_quiesce_queue(q); > blk_mq_unfreeze_queue(q, memflags); > > /* Ensure we don't receive any more interrupts */ > > --- > base-commit: 50d05c7c76c96b90462f24debacca971d2e86713 > change-id: 20260910-virtblk_sync_quiesce-9b2c88d45416 > > Best regards, > -- > Cong Zhang <[email protected]> > Other than this, Acked-by: Jason Wang <[email protected]> Thanks
