linux-kernel - Re: [PATCH RFC fs/namespace] Make kern_unmount() use synchronize_rcu

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Date:   Wed, 27 Apr 2022 12:19:56 +0000
From:   Chris Mason <clm@...com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
CC:     Christoph Bartoschek <bartoschek@...gle.com>,
        Giuseppe Scrivano <gscrivan@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "riel@...riel.com" <riel@...riel.com>,
        "viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>
Subject: Re: [PATCH RFC fs/namespace] Make kern_unmount() use
 synchronize_rcu_expedited()


> On Apr 26, 2022, at 7:11 PM, Paul E. McKenney <paulmck@...nel.org> wrote:
> 
> On Wed, Apr 27, 2022 at 12:58:34AM +0200, Christoph Bartoschek wrote:
>>> 3. https://lore.kernel.org/lkml/20220218183114.2867528-1-riel@surriel.com/
>>> 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@zeniv-ca.linux.org.uk/

-chris