linux-kernel - Re: [PATCH] rcu: Allow rcu_irq_enter_check

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Mon, 16 Nov 2020 12:00:04 -0800
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Peter Zijlstra <peterz@...radead.org>, eupm90@...il.com,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH] rcu: Allow rcu_irq_enter_check_tick() from NMI

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 <peterz@...radead.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@...il.com>
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> > Reviewed-by: Andy Lutomirski <luto@...nel.org>
> > Reviewed-by: Paul E. McKenney <paulmck@...nel.org>
> 
> Reviewed-by: Thomas Gleixner <tglx@...utronix.de>

Queued, thank you all!

							Thanx, Paul