Re: [PATCH V12] mm/debug: Add tests validating architecture page table helpers

[Christophe Leroy]

Le 02/02/2020 Ã 12:26, Qian Cai a ÃcritÂ:
> > On Jan 30, 2020, at 9:13 AM, Christophe Leroy <christophe.leroy@xxxxxx> wrote:
> >
> > config DEBUG_VM_PGTABLE
> >     bool "Debug arch page table for semantics compliance" if ARCH_HAS_DEBUG_VM_PGTABLE || EXPERT
> >     depends on MMU
> >     default 'n' if !ARCH_HAS_DEBUG_VM_PGTABLE
> >     default 'y' if DEBUG_VM
>
> Does it really necessary to potentially force all bots to run this? Syzbot, kernel test robot etc? Does it ever pay off for all their machine times there?

Machine time ?

On a 32 bits powerpc running at 132 MHz, the tests takes less than 10ms. 
Is it worth taking the risk of not detecting faults by not selecting it 
by default ?

[    5.656916] debug_vm_pgtable: debug_vm_pgtable: Validating 
architecture page table helpers
[    5.665661] debug_vm_pgtable: debug_vm_pgtable: Validated 
architecture page table helpers

Christophe