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

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Message-ID: <cf61db81-be9f-437c-a53b-a82b0232d207@nvidia.com>
Date: Thu, 5 Feb 2026 20:22:46 -0500
From: Joel Fernandes <joelagnelf@...dia.com>
To: Peter Zijlstra <peterz@...radead.org>, Lyude Paul <lyude@...hat.com>
Cc: 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 2/3/2026 6:44 AM, Peter Zijlstra wrote:
> On Wed, Jan 21, 2026 at 05:39:05PM -0500, Lyude Paul wrote:
> 
>> diff --git a/kernel/softirq.c b/kernel/softirq.c
>> index 77198911b8dd4..af47ea23aba3b 100644
>> --- a/kernel/softirq.c
>> +++ b/kernel/softirq.c
>> @@ -88,6 +88,8 @@ EXPORT_PER_CPU_SYMBOL_GPL(hardirqs_enabled);
>>  EXPORT_PER_CPU_SYMBOL_GPL(hardirq_context);
>>  #endif
>>  
>> +DEFINE_PER_CPU(unsigned int, nmi_nesting);
> 
> What happened with putting this in the same line as preempt_count?

I can try to do that again if we still want to go with this patch. When I tried
that last, I ran into issues I can't remember now (the space being limited?).