Re: [PATCH v3 01/22] hardirq/nmi: Allow nested nmi_enter()

From: Peter Zijlstra
Date: Wed Feb 19 2020 - 12:07:58 EST

On Wed, Feb 19, 2020 at 05:56:50PM +0100, Borislav Petkov wrote:
> On Wed, Feb 19, 2020 at 10:31:26AM -0500, Steven Rostedt wrote:
> > Probably should document somewhere (in a comment above nmi_enter()?)
> > that we allow nmi_enter() to nest up to 15 times.
> Yah, and can we make the BUG_ON() WARN_ON or so instead, so that there's
> at least a chance to be able to catch it for debugging. Or is the box
> going to be irreparably wedged after the 4 bits overflow?

It's going to be fairly buggered, because at that point in_nmi() is
going to be false again. It might survive for a little, it might not.