Re: [V5 PATCH 2/4] panic/x86: Allow cpus to save registers even if they are looping in NMI context

Steven Rostedt
2015-11-24T19:37:11Z

On Tue, Nov 24, 2015 at 11:48:53AM +0100, Borislav Petkov wrote:
>
> > + */
> > + while (!raw_spin_trylock(&nmi_reason_lock))
> > + poll_crash_ipi_and_callback(regs);
>
> Waaait a minute: so if we're getting NMIs broadcasted on every core but
> we're *not* crash dumping, we will run into here too. This can't be
> right. :-\

This only does something if crash_ipi_done is set, which means you are killing
the box. But perhaps a comment that states that here would be useful, or maybe
just put in the check here. There's no need to make it depend on SMP, as
raw_spin_trylock() will turn to just ({1}) for UP, and that code wont even be
hit.

-- Steve