On Mon, 13 Dec 2021 21:55:27 +0900, Tetsuo Handa wrote:

syzbot is reporting circular locking problem at __loop_clr_fd() [1], for
commit 87579e9b7d8dc36e ("loop: use worker per cgroup instead of kworker")
is calling destroy_workqueue() with disk->open_mutex held.

This circular dependency cannot be broken unless we call __loop_clr_fd()
without holding disk->open_mutex. Therefore, defer __loop_clr_fd() from
lo_release() to a WQ context.

[...]

Applied, thanks!

[1/1] loop: make autoclear operation asynchronous
      commit: 322c4293ecc58110227b49d7e47ae37b9b03566f

Best regards,
-- 
Jens Axboe