Re: [patch, -rc5-mm1] lock validator: disable NMI watchdog ifCONFIG_LOCKDEP, i386

From: Andrew Morton
Date: Tue May 30 2006 - 15:49:54 EST


On 30 May 2006 21:14:54 +0200
Andi Kleen <ak@xxxxxxx> wrote:

> Ingo Molnar <mingo@xxxxxxx> writes:
> >
> > The NMI watchdog uses spinlocks (notifier chains, etc.),
> > so it's not lockdep-safe at the moment.
>
> That's totally unsafe even without lockdep and should be fixed
> instead. I guess someone bungled the notifier chain conversion.
> The NMI notifiers need to be lockless.
>

Confused. NMI uses notify_die(), which doesn't take locks?

We'll probably accidentally take locks when actually reporting an NMI
watchdog timeout, but that doesn't seem terribly important.
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