Re: [RFC PATCH] pipe: make pipe_release() deferrable.

[Linus Torvalds]

On Fri, Aug 21, 2020 at 9:35 PM Tetsuo Handa
<penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:
>
> Therefore, this patch tries to convert __pipe_lock() in pipe_release() to
> killable, by deferring to a workqueue context when __pipe_lock_killable()
> failed.

I don't think this is an improvement.

If somebody can delay the pipe unlock arbitrarily, you've now turned a
user-visible blocking operation into blocking a workqueue instead. So
it's still there, and now it possibly is much worse and blocks
system_wq instead.

                Linus