Bug Report: can't unload nvme module in case of disabled device

[Keith Busch]

On Sun, Aug 13, 2017 at 11:29:59AM +0300, Max Gurtovoy wrote:
> 
> After bisecting I found that the following commit caused the simple
> load/unload nvme driver failure:
> 
> commit 1ad43c0078b79a76accd0fe64062e47b3430dc6b
> Author: Ming Lei <minlei at redhat.com>
> Date:   Wed Aug 2 08:01:45 2017 +0800
> 
>     blk-mq: don't leak preempt counter/q_usage_counter when allocating rq
> failed
> 
> Adding Ming to this thread.
> 
> I'm continuing with the debug of the new scenario (load nvme && sleep 10 &&
> unload nvme).
 
I'm reviewing that commit, and it looks wrong to me. It is only pairing
the blk_queue_exit if request allocation was successful. That will get
the q_usage_counter off when request allocation fails, making a queue
freeze impossible. I'll send a patch.