Re: [PATCH RFC fs/namespace] Make kern_unmount() use synchronize_rcu_expedited()

From: Paul E. McKenney
Date: Wed Apr 27 2022 - 11:01:50 EST


On Wed, Apr 27, 2022 at 12:19:56PM +0000, Chris Mason wrote:
>
> > On Apr 26, 2022, at 7:11 PM, Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
> >
> > On Wed, Apr 27, 2022 at 12:58:34AM +0200, Christoph Bartoschek wrote:
> >>> 3. https://lore.kernel.org/lkml/20220218183114.2867528-1-riel@xxxxxxxxxxx/
> >>> Refined queue_rcu_work() approach.
> >>>
> >>> #1 should work, but the resulting IPIs are not going to make the real-time
> >>> guys happy. #2 and #3 have been subject to reasonably heavy testing
> >>> and did fix a very similar issue to the one that you are reporting,
> >>> but last I knew there were doubts about the concurrency consequences.
> >>>
> >>> Could you please give at least #3 a shot and see if it helps you?
> >>
> >> I have tried #3 and it works well with my testcases as far as I can see it.
> >
> > Thank you for giving it a try!
> >
> > Al, are further adjustments needed to make this patch cover all the
> > corner cases?
>
> Did we end up addressing all of Al’s comments here?
>
> https://lore.kernel.org/lkml/YhCFKyVMtOSyBDJh@xxxxxxxxxxxxxxxxxxxxx/

Indeed we have not! Thank you for the reminder, and I will get with
Rik to look into this.

Thanx, Paul