linux-kernel - Re: [RFC PATCH v2 15/20] context-tracking: Introduce work deferral infrastructure

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Date:   Mon, 24 Jul 2023 21:18:57 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Valentin Schneider <vschneid@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, kvm@...r.kernel.org, linux-mm@...ck.org,
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        Yair Podemsky <ypodemsk@...hat.com>
Subject: Re: [RFC PATCH v2 15/20] context-tracking: Introduce work deferral
 infrastructure

On Mon, Jul 24, 2023 at 05:55:44PM +0100, Valentin Schneider wrote:
> I can make that a 'do {} while ()' instead to force at least one execution
> of the cmpxchg().
> 
> This is only about reducing the race window, right? If we're executing this
> just as the target CPU is about to enter userspace, we're going to be in
> racy territory anyway. Regardless, I'm happy to do that change.

Right, it's only about narrowing down the race window. It probably don't matter
in practice, but it's one less thing to consider for the brain :-)

Also, why bothering with handling CONTEXT_IDLE?

Thanks.