Re: [PATCH RFC V10 15/18] kvm : Paravirtual ticketlocks support forlinux guests running on KVM hypervisor

[Raghavendra K T]

On 07/16/2013 09:18 PM, Peter Zijlstra wrote:
> On Tue, Jul 16, 2013 at 09:02:15AM +0300, Gleb Natapov wrote:
> > BTW can NMI handler take spinlocks?
>
> No -- that is, yes you can using trylock, but you still shouldn't.

Thanks Peter for the clarification.

I had started checking few of nmi handlers code to confirm.
Did saw a raw spinlock in drivers/acpi/apei/ghes.c, but then stopped.

> > If it can what happens if NMI is
> > delivered in a section protected by local_irq_save()/local_irq_restore()?
>
> You deadlock.

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