From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 2/2] locking/pvqspinlock: Optionally store lock holder
 cpu into lock
Date: Tue, 14 Jul 2020 11:01:26 +0200
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To: Waiman Long <longman@redhat.com>
Cc: Nicholas Piggin <npiggin@gmail.com>, Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>, Davidlohr Bueso <dave@stgolabs.net>, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Will Deacon <will.deacon@arm.com>, x86@kernel.org

On Mon, Jul 13, 2020 at 10:48:00PM -0400, Waiman Long wrote:
> Storing the cpu number into the lock can be useful for other reason too. It
> is not totally related to PPC support.

Well, the thing you did only works for 'small' (<253 CPU) systems.
There's a number of Power systems that's distinctly larger than that. So
it simply cannot work as anything other than a suggestion/hint. It must
not be a correctness thing.