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

[Steven Rostedt]

On Tue, 24 Nov 2015 21:27:13 +0100
Michal Hocko <mhocko at 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