Re: WARNING: possible circular locking dependency detected in nbd

On Thu, Aug 19, 2021 at 03:29:38PM +0800, Hillf Danton wrote:

On Wed, 18 Aug 2021 09:10:49 +0200 Sven Schnelle wrote:

quoted

Hi,

i'm seeing the lockdep splat below in CI. I think this is because

Thanks for reporting it.

quoted

nbd_open is called with disk->open_mutex held, and acquires
nbd_index_mutex. However, nbd_put() first takes the nbd_index_lock,
and calls del_gendisk, which locks disk->open_mutex, so the order is
reversed.

Right. See diff attached.

This is already fixed in linux-next.