Re: [PATCH 2/2] blk-mq: ensure a q_usage_counter reference is held when splitting bios

Christoph Hellwig
2024-01-11T16:14:45Z

On Thu, Jan 11, 2024 at 09:12:23AM -0700, Jens Axboe wrote:
> On 1/11/24 6:57 AM, Christoph Hellwig wrote:
> > q_usage_counter is the only thing preventing us from the limits changing
> > under us in __bio_split_to_limits, but blk_mq_submit_bio doesn't hold it.
> >
> > Change __submit_bio to always acquire the q_usage_counter counter before
> > branching out into bio vs request based helper, and let blk_mq_submit_bio
> > tell it if it consumed the reference by handing it off to the request.
>
> This causes hangs for me on shutdown/reset:

> which seems to indicate that a reference is being leaked. Haven't poked
> any further at it, I'll drop these two for now.

Can you send me your .config?