Re: [crash] PANIC: double fault, error_code: 0x0

[Ingo Molnar <mingo@kernel.org>]

* Andy Lutomirski <luto@kernel.org> wrote:

> On Fri, Nov 24, 2017 at 12:22 PM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Ingo Molnar <mingo@kernel.org> wrote:
> >
> >> This is a repost of the latest entry-stack plus Kaiser bits from Andy Lutomirski
> >> (v3 series from today) and Dave Hansen (kaiser-414-tipwip-20171123 version),
> >> on top of latest tip:x86/urgent (12a78d43de76).
> >>
> >> This version is pretty well tested, at least on the usual x86 tree test systems.
> >> It has a couple of merge mistakes fixed, the biggest difference is in patch #22:
> >>
> >>   x86/mm/kaiser: Prepare assembly for entry/exit CR3 switching
> >>
> >> The other patches are identical or very close to what I posted earlier today.
> >
> > Here's a new bug, on a testsystem I get the double fault boot crash attached
> > below. The same bzImage crashes on other systems as well, so it's not CPU
> > dependent.
> >
> > Via Kconfig-bisection I have narrowed it down to the following .config detail:
> > it's triggered by _disabling_ CONFIG_DEBUG_ENTRY and enabling CONFIG_KAISER=y.
> >
> > I.e. one of the sanity checks of CONFIG_DEBUG_ENTRY has some positive side effect.
> 
> That's weird and definitely not intentional.

Btw., can you reproduce the crash by disabling CONFIG_DEBUG_ENTRY with 
CONFIG_KAISER=y?

Thanks,

	Ingo