Re: [PATCH] drm/virtio: add timeout to virtqueue wait to avoid hung task

[Dmitry Osipenko <dmitry.osipenko@collabora.com>]

Hi,

On 5/12/26 11:59, Ryosuke Yasuoka wrote:
> virtio_gpu_queue_ctrl_sgs() and virtio_gpu_queue_cursor() use
> wait_event() without timeout when waiting for virtqueue space. If the
> host device stops processing commands, these waits block indefinitely.
> Since callers may hold DRM locks, this can make the entire system
> unresponsive.
> 
> Replace wait_event() with wait_event_timeout() using a 5-second timeout,
> consistent with the existing timeout pattern in the driver. On timeout,
> clean up and return -ENODEV, following the same error path as
> drm_dev_enter() failure.
> 
> Reported-by: syzbot+d6dd6f86d3aaf7eebe7406e45c1c6e549453f224@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?id=d6dd6f86d3aaf7eebe7406e45c1c6e549453f224
> Reported-by: syzbot+908bd910da5dd79b88de4cf7baf376cc873a922e@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?id=908bd910da5dd79b88de4cf7baf376cc873a922e
> Signed-off-by: Ryosuke Yasuoka <ryasuoka@redhat.com>
> ---
>  drivers/gpu/drm/virtio/virtgpu_vq.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)

If host stops processing commands, this is a problem on host side. Isn't it?

-- 
Best regards,
Dmitry