linux-kernel - Re: [RFC PATCH v3 04/15] rcu: Add a small-width RCU watching counter debug option

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Message-ID: <20241120145049.GI19989@noisy.programming.kicks-ass.net>
Date: Wed, 20 Nov 2024 15:50:49 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Valentin Schneider <vschneid@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	kvm@...r.kernel.org, linux-mm@...ck.org, bpf@...r.kernel.org,
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Subject: Re: [RFC PATCH v3 04/15] rcu: Add a small-width RCU watching counter
 debug option

On Tue, Nov 19, 2024 at 04:34:51PM +0100, Valentin Schneider wrote:
> A later commit will reduce the size of the RCU watching counter to free up
> some bits for another purpose. Paul suggested adding a config option to
> test the extreme case where the counter is reduced to its minimum usable
> width for rcutorture to poke at, so do that.
> 
> Make it only configurable under RCU_EXPERT. While at it, add a comment to
> explain the layout of context_tracking->state.

Note that this means it will get selected by allyesconfig and the like,
is that desired?

If no, depends on !COMPILE_TEST can help here.