Re: [PATCH v2 00/18] Entry stack switching

From: Ingo Molnar
Date: Thu Nov 23 2017 - 01:58:42 EST

* Ingo Molnar <mingo@xxxxxxxxxx> wrote:

> * Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> > > Anyway, I booted your config (more or less -- I munged it through
> > > virtme-configkernel --update first) with 17 vCPUs and it seems fine.
> > > Is the issue reliable enough to bisect?
> >
> > Ok, it should be bisectable, will try to bisect it.
> The latestest entry-stack code appears to be working fine though.
> So one of the below fixes from yesterday appears to have done the trick.
> I'll re-test today to make sure: maybe it's more sporadic than I thought, in one
> of the bootups I got the do_IRQ warning only once, in half a day of uptime.

I re-tested and it all seems fine now. I suspect it got fixed by:

ca37e57bbe0c: x86/entry/64: Add missing irqflags tracing to native_load_gs_index()

still it is weird, because I boot that system with latest -tip on a daily basis,
and don't remember having seen that warning.

Do you have any theory for why the entry stack changes would uncover this bug?