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From: Andreas Hindborg <a.hindborg@kernel.org>
To: Lyude Paul <lyude@redhat.com>, rust-for-linux@vger.kernel.org, Thomas
 Gleixner <tglx@linutronix.de>, Boqun Feng <boqun.feng@gmail.com>,
 linux-kernel@vger.kernel.org, Daniel Almeida
 <daniel.almeida@collabora.com>
Cc: Joel Fernandes <joelagnelf@nvidia.com>, Ingo Molnar <mingo@redhat.com>,
 Peter Zijlstra <peterz@infradead.org>, Juri Lelli <juri.lelli@redhat.com>,
 Vincent Guittot <vincent.guittot@linaro.org>, Dietmar Eggemann
 <dietmar.eggemann@arm.com>, Steven Rostedt <rostedt@goodmis.org>, Ben
 Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>, Valentin
 Schneider <vschneid@redhat.com>
Subject: Re: [PATCH v13 02/17] preempt: Reduce NMI_MASK to single bit and
 restore HARDIRQ_BITS
In-Reply-To: <20251013155205.2004838-3-lyude@redhat.com>
References: <20251013155205.2004838-1-lyude@redhat.com>
 <20251013155205.2004838-3-lyude@redhat.com>
Date: Tue, 04 Nov 2025 13:15:34 +0100
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Lyude Paul <lyude@redhat.com> writes:

> From: Joel Fernandes <joelagnelf@nvidia.com>
>
> Now that NMI nesting is tracked in a separate per-CPU variable
> (nmi_nesting), we no longer need multiple bits in preempt_count
> for NMI tracking. Reduce NMI_BITS from 3 to 1, using it only to
> detect if we're in an NMI.
>
> Signed-off-by: Joel Fernandes <joelaf@google.com>
> Signed-off-by: Lyude Paul <lyude@redhat.com>

The commit summary is mentioning HARDIRQ_BITS, but I don't think that
change is part of this commit.


Best regards,
Andreas Hindborg