linux-kernel - Re: #PF from NMI

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Message-ID: <20201116114629.1e1894be@gandalf.local.home>
Date:   Mon, 16 Nov 2020 11:46:29 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Paul McKenney <paulmck@...nel.org>, eupm90@...il.com,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: #PF from NMI

On Sat, 14 Nov 2020 00:13:58 +0100
Thomas Gleixner <tglx@...utronix.de> wrote:

> nmi:
>   ...
>   trace_hardirqs_off_finish() {
>     if (!this_cpu_read(tracing_irq_cpu)) {
>            this_cpu_write(tracing_irq_cpu, 1);
>            ...
>   }
>   ...
>   perf()
> 
> #PF
>   save_cr2()
>   
>   irqentry_enter()
>      trace_hardirqs_off_finish()
>         if (!this_cpu_read(tracing_irq_cpu)) {
> 
> So yes, it is recursion protected unless I'm missing something.

That should work.

-- Steve