RE: [PATCH v1 0/3] udmabuf: Add support for page migration out of movable zone or CMA

["Kasireddy, Vivek" <vivek.kasireddy@intel.com>]

Hi Jason, David,

> > > Sure, we can simply always fail when we detect ZONE_MOVABLE or
> > MIGRATE_CMA.
> > > Maybe that keeps at least some use cases working.
> >
> > That seems fairly reasonable
> AFAICS, failing udmabuf_create() if we detect one or more pages are in
> ZONE_MOVABLE or MIGRATE_CMA would not be a recoverable failure --
> as it would result in the failure of Guest GUI (or compositor).
> 
> I think it makes sense to have a generic version of
> And, since check_and_migrate_movable_pages() is GUP-specific, would
> it be ok to create a generic version of that (in mm/migrate.c) which can be
> used by udmabuf and/or other drivers in the future?
Sorry, I accidentally sent this earlier email before finishing it. 
What I meant to say is since the same situation (inadvertently pinning pages
in movable) may probably arise in the future with another driver, I think it makes
sense to have a generic (non-GUP) version of check_and_migrate_movable_pages()
available in migration.h that drivers can use to ensure that they don't break
memory hotunplug accidentally.

Thanks,
Vivek

> 
> Thanks,
> Vivek
> 
> >
> > Jason
>