linux-kernel - Re: [PATCH v17 02/16] preempt: Track NMI nesting to separate per-CPU counter

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Message-ID: <1770502064.0c13dda338916c42@nvidia.com>
Date: Sat, 7 Feb 2026 17:11:42 -0500
From: Joel Fernandes <joelagnelf@...dia.com>
To: Boqun Feng <boqun@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Lyude Paul <lyude@...hat.com>,
	rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Boqun Feng <boqun.feng@...il.com>,
	Daniel Almeida <daniel.almeida@...labora.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>, Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>
Subject: Re: [PATCH v17 02/16] preempt: Track NMI nesting to separate per-CPU
 counter

On Fri, Feb 06, 2026 at 08:16:39AM -0800, Boqun Feng wrote:
[...]
> Yeah, "can't" is a strong word? ;-) I did say if we care more about
> performance on 64bit than 32bit and can afford slowing down 32bit
> preemption disabling in the case where "we decide to have additional
> preempt count flags", THEN we can make all preempt count 64bit.

Ok, hopefully x86 32-bit goes away before we have to maintain/improve
these workarounds in it. :-)

-- 
Joel Fernandes

-- 
-- 
Joel Fernandes