Re: [6.5-rc5 regression] core dump hangs (was Re: [Bug report] fstests generic/051 (on xfs) hang on latest linux v6.5-rc5+)

[Eric W. Biederman]

Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> writes:

> On Mon, Jun 12, 2023 at 9:45 AM Jens Axboe <axboe@xxxxxxxxx> wrote:
>>
>> You snipped the suspicion in my reply on why that exists, to avoid
>> io_wq_worker_sleeping() triggering.
>
> I'm not seeing why triggering io_wq_worker_sleeping() should even be a
> problem in the first place.
>
> I suspect that is entirely historical too, and has to do with how it
> used to do that
>
>         struct io_worker *worker = kthread_data(tsk);
>         struct io_wqe *wqe = worker->wqe;
>
> back in the bad old days of kthreads.
>
> But yeah, I don't know that code.

If it is a problem it looks like the thread shutdown can clear
"worker->flags & IO_WORKER_F_UP" rather than
"current->flags & PF_IO_WORKER".

I don't see how it makes sense for the load balancing logic for
a per-process thread pool to be running at that point.

Eric