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

* Ingo Molnar <mingo@kernel.org> wrote:

>
> * Andy Lutomirski <luto@kernel.org> wrote:
>
> > This sets up stack switching, including for SYSCALL. I think it's
> > in decent shape.
> >
> > Known issues:
> > - I think we're going to want a way to turn the stack switching on and
> > off either at boot time or at runtime. It should be fairly straightforward
> > to make it work.
> >
> > - I think the ORC unwinder isn't so good at dealing with stack overflows.
> > It bails too early (I think), resulting in lots of ? entries. This
> > isn't a regression with this series -- it's just something that could
> > be improved.
> >
> > Ingo, patch 1 may be tip/urgent material. It fixes what I think is
> > a bug in Xen. I'm having a hard time testing because it's being
> > masked by a bigger unrelated bug that's keeping Xen from booting
> > when configured to hit the bug I'm fixing. (The latter bug goes at
> > least back to v4.13, I think I know roughtly what's wrong, and I've
> > reported it to the maintainers.)
>
> Hm, with this series the previous IRQ vector bug appears again:
>
> [ 51.156370] do_IRQ: 16.34 No irq handler for vector
> [ 57.511030] do_IRQ: 16.34 No irq handler for vector
> [ 57.528335] do_IRQ: 16.34 No irq handler for vector
> [ 57.533256] do_IRQ: 16.34 No irq handler for vector
> [ 63.991913] do_IRQ: 16.34 No irq handler for vector
> [ 63.996810] do_IRQ: 16.34 No irq handler for vector
>
> I've attached the reproducer config. Note that the system appears to be working to
> a certain extent (I could ssh to it and extract its config), but produces these
> warnings sporadically.
>
> Also note that this is the same AMD system tha had irq-tracing/lockdep troubles
> yesterday. So maybe this warning is related and we either have broken lockdep, or
> these IRQ vector warnings.

Yeah, so I just double checked, if from the latest series I revert:

x86/entry/64: Fix entry_SYSCALL_64_after_hwframe() IRQ tracing

then I (no surprise) get the bootup lockdep warning - but don't get the IRQ vector
warnings.

Thanks,

Ingo

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