Re: [PATCH] x86/orc: Don't bail on stack overflow

From: Ingo Molnar
Date: Mon Nov 27 2017 - 04:38:52 EST



* Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:

> On Sat, Nov 25, 2017 at 04:16:23PM -0800, Andy Lutomirski wrote:
> > Can you send me whatever config and exact commit hash generated this?
> > I can try to figure out why it failed.
>
> Sorry, I've been traveling. I just got some time to take a look at
> this. I think there are at least two unwinder issues here:
>
> - It doesn't deal gracefully with the case where the stack overflows and
> the stack pointer itself isn't on a valid stack but the
> to-be-dereferenced data *is*.
>
> - The oops dump code doesn't know how to print partial pt_regs, for the
> case where if we get an interrupt/exception in *early* entry code
> before the full pt_regs have been saved.
>
> (Andy, I'm not quite sure about your patch, and whether it's still
> needed after these patches. I'll need to look at it later when I have
> more time.)
>
> I attempted to fix both of the issues with the below patch. Thomas or
> Ingo, can you test to see if this gets rid of the question marks?
>
> I can split it up into proper patches next week. I'm assuming this
> isn't holding up the KAISER merge?

It's not holding up the Kaiser merge, but good debuggability of weird crashes is a
really good thing, so I constructed a changelog and picked up this patch as a
single commit, and added your Signed-off-by, if that's OK with you.

Will only push it out if it passes testing.

Thanks,

Ingo