On Mon, Nov 16, 2020 at 06:24:31PM +0100, Thomas Gleixner wrote:
> 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 <pet...@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" <eup...@gmail.com>
> > Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
> > Reviewed-by: Andy Lutomirski <l...@kernel.org>
> > Reviewed-by: Paul E. McKenney <paul...@kernel.org>
>
> Reviewed-by: Thomas Gleixner <t...@linutronix.de>
Queued, thank you all!
Thanx, Paul
