Re: [V5 PATCH 1/4] panic/x86: Fix re-entrance problem due to panic on NMI

Steven Rostedt
2015-11-24T20:45:37Z

On Tue, 24 Nov 2015 21:27:13 +0100
Michal Hocko <mhocko@kernel.org> wrote:

> > What happens if:
> >
> > CPU 0: CPU 1:
> > ------ ------
> > nmi_panic();
> >
> > nmi_panic();
> > <external nmi>
> > nmi_panic();
>
> I thought that nmi_panic is called only from the nmi context. If so how
> can we get a nested NMI like that?

Nevermind. I was thinking the external NMI could nest, but I'm guessing
it cant. Anyway, the patches later on modify this code which checks for
something other than != this_cpu, which makes this issue mute even if
it could nest.

-- Steve