Re: [PATCH v12 08/11] mm: Clear arch specific VM flags on protection change

[Khalid Aziz]

On 03/05/2018 12:23 PM, Dave Hansen wrote:
> On 02/21/2018 09:15 AM, Khalid Aziz wrote:
> > +/* Arch-specific flags to clear when updating VM flags on protection change */
> > +#ifndef VM_ARCH_CLEAR
> > +# define VM_ARCH_CLEAR	VM_NONE
> > +#endif
> > +#define VM_FLAGS_CLEAR	(ARCH_VM_PKEY_FLAGS | VM_ARCH_CLEAR)
>
> Shouldn't this be defining
>
> # define VM_ARCH_CLEAR	ARCH_VM_PKEY_FLAGS
>
> on x86?

ARCH_VM_PKEY_FLAGS is used by x86 as well as powerpc. On those two 
architectures VM_FLAGS_CLEAR will end up being ARCH_VM_PKEY_FLAGS and 
thus current behavior will be retained. Defining VM_ARCH_CLEAR to be 
ARCH_VM_PKEY_FLAGS on x86 will just result in VM_FLAGS_CLEAR to be 
(ARCH_VM_PKEY_FLAGS | ARCH_VM_PKEY_FLAGS) which is superfluous.

--
Khalid