From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>,
"Paul E. McKenney" <paulmck@kernel.org>
Cc: eupm90@gmail.com, linux-kernel@vger.kernel.org, x86@kernel.org,
Andy Lutomirski <luto@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] rcu: Allow rcu_irq_enter_check_tick() from NMI
Date: Mon, 16 Nov 2020 18:24:31 +0100 [thread overview]
Message-ID: <87a6vhz034.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201116121012.GC3121378@hirez.programming.kicks-ass.net>
On Mon, Nov 16 2020 at 13:10, Peter Zijlstra wrote:
> Any which way around; here's a proper patch...
>
> ---
>
> Subject: rcu: Allow rcu_irq_enter_check_tick() from NMI
> From: Peter Zijlstra <peterz@infradead.org>
> Date: Mon Nov 16 12:54:56 CET 2020
>
> Eugenio managed to tickle #PF from NMI context which resulted in
> hitting a WARN in RCU through irqentry_enter() ->
> __rcu_irq_enter_check_tick().
>
> However, this situation is perfectly sane and does not warrant an
> WARN. The #PF will (necessarily) be atomic and not require messing
> with the tick state, so early return is correct.
>
> Fixes: aaf2bc50df1f ("rcu: Abstract out rcu_irq_enter_check_tick() from rcu_nmi_enter()")
> Reported-by: "Eugenio Pérez" <eupm90@gmail.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Reviewed-by: Andy Lutomirski <luto@kernel.org>
> Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
next prev parent reply other threads:[~2020-11-16 17:25 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 12:53 #PF from NMI Peter Zijlstra
2020-11-13 17:16 ` Paul E. McKenney
2020-11-13 17:23 ` Andy Lutomirski
2020-11-13 23:13 ` Thomas Gleixner
2020-11-14 1:05 ` Paul E. McKenney
2020-11-16 12:10 ` [PATCH] rcu: Allow rcu_irq_enter_check_tick() " Peter Zijlstra
2020-11-16 17:24 ` Thomas Gleixner [this message]
2020-11-16 20:00 ` Paul E. McKenney
2020-11-16 16:46 ` #PF " Steven Rostedt
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