Re: tip -ENOBOOT - bisected to locking/refcounts, x86/asm: Implement fast refcount overflow protection

From: Mike Galbraith
Date: Tue Aug 29 2017 - 05:23:09 EST


On Tue, 2017-08-29 at 10:58 +0200, Ingo Molnar wrote:
> * Mike Galbraith <efault@xxxxxx> wrote:
>
> > Greetings,
> >
> > Take 2 of KVM bisect as you work fingered $subject. ÂTake 1 was stymied
> > by build dependencies (aa5d1b81, df340524) which I foolishly tried to
> > skip, leading git bisect to end up handing me a list of commits that
> > might be busted. ÂDuring take 2, I added those two as required.
> >
> > Symptom is a few splats as below, with box finally hanging. ÂNetwork
> > comes up, but neither ssh nor console login is possible.
>
> Just to double check, does the patch below also cure the regression?
> If we don't find the bug it might be safer than a full revert.

I reverted it, and vbox now boots. ÂShould I still try the below?

>
> Thanks,
>
> Ingo
>
> arch/x86/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index d04809921993..3b83ef8f1e9b 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -55,7 +55,7 @@ config X86
> select ARCH_HAS_KCOV if X86_64
> select ARCH_HAS_MMIO_FLUSH
> select ARCH_HAS_PMEM_API if X86_64
> - select ARCH_HAS_REFCOUNT
> +# select ARCH_HAS_REFCOUNT
> select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
> select ARCH_HAS_SET_MEMORY
> select ARCH_HAS_SG_CHAIN