Re: [mm/debug] fa6726c1e7: kernel_BUG_at_include/linux/mm.h

[Christophe Leroy]

Le 28/04/2020 Ã 04:51, Qian Cai a ÃcritÂ:
> > On Apr 27, 2020, at 10:35 PM, Anshuman Khandual <Anshuman.Khandual@xxxxxxx> wrote:
> >
> > Letting CONFIG_DEBUG_VM_PGTABLE enabled via CONFIG_EXPERT for unsupported
> > platforms i.e without ARCH_HAS_DEBUG_VM_PGTABLE, was a conscious decision
> > meant to expand it's adaptability and coverage without requiring any code
> > (i.e Kconfig) change. The easier it is to enable the test on unsupported
> > platforms right now, more folks are likely to try it out thus increasing
> > it's probability to get fixed on those platforms. That is a valid enough
> > reason to have CONFIG_EXPERT based enablement method, IMHO. Also even with
> > CONFIG_EXPERT set, CONFIG_DEBUG_VM_PGTABLE does not get enabled by default
> > automatically.
>
> No, I am talking about PAE. There is a distinction between known broken that nobody cares (like arm32) and in-progress/unknown status (like s390).
>
> Also, it is not very nice to introduce regressions for robots when testing PAE because they always select CONFIG__EXPERT and CONFIG_DEBUG_VM.

Having CONFIG_EXPERT and CONFIG_DEBUG_VM is not enough to get 
CONFIG_DEBUG_VM_PGTABLE set to yes.

By default, CONFIG_DEBUG_VM_PGTABLE is set to no when 
ARCH_HAS_DEBUG_VM_PGTABLE is not set.

Christophe