Re: [REGRESSION] io_uring: final close can hang on a stopped submitter

[Karl Mehltretter]

On Tue, Oct 27, 2026 at 12:04:59PM +0100, Jens Axboe wrote:
> >   3. A unmaps the ring but keeps its fd. B drops its fd and mappings,
> >      then stops itself with SIGSTOP.
> >   4. After confirming that B is stopped, controller P tells A to close
> >      the final ring fd.
> >   5. P resumes B after two seconds so the test can finish.
> > 
> > B keeps both pipe ends open and remains alive until close returns. This
> > excludes pipe HUP and process exit as completion sources.
> 
> This is working as intended. With the change, close() waits for
> requests still in flight, as otherwise they keep files pinned after
> the ring is gone. If you SIGSTOP a task, then that task can't run
> the required work to complete it. A fatal signal will still kill
> it.
> 
> Unsurprisingly, sending SIGSTOP to something may prevent it from
> doing work...
> 

Good point. This is not a real regression.

Thanks,
Karl