[PATCH v9 00/18] drm/virtio: switch from ttm to gem shmem helpers.

[Gerd Hoffmann]

On Thu, Aug 29, 2019 at 04:44:49PM -0700, Chia-I Wu wrote:
> The series is
> 
>   Reviewed-by: Chia-I Wu <olvaffe at gmail.com>

Thanks.

> However I ran into a deadlock with one GPU-heavy app.  When I exits
> Unigine Valley benchmark with ctrl-c, the entire driver locks up
> probably 8 out of 10 times on my machine.  When that happens,
> virtio_gpu_dequeue_ctrl_func does not return and is blocked inside
> virtio_gpu_array_put_free.
> 
> It seems, when the vq becomes full or near full between reclaim_vbufs
> and virtio_gpu_array_put_free, virtio_gpu_array_put_free can not free
> all of the objects because each call to virtio_gpu_free_object needs
> to add several commands to vq.  One of the calls ends up being blocked
> at "wait_event(vgdev->ctrlq.ack_queue, ...)".

Probably it is simply the large number of objects released at once when
killing the benchmark which causes the queue to fill up.

cheers,
  Gerd