Re: [PATCH v4 23/23] mm/gup: remove support for gup(FOLL_LONGTERM)

[John Hubbard]

On 11/13/19 11:09 AM, Ira Weiny wrote:
...
> > diff --git a/mm/gup.c b/mm/gup.c
> > index 82e7e4ce5027..90f5f95ee7ac 100644
> > --- a/mm/gup.c
> > +++ b/mm/gup.c
> > @@ -1756,11 +1756,11 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
> >   		struct vm_area_struct **vmas)
> >   {
> >   	/*
> > -	 * FOLL_PIN must only be set internally by the pin_user_page*() and
> > -	 * pin_longterm_*() APIs, never directly by the caller, so enforce that
> > -	 * with an assertion:
> > +	 * FOLL_PIN and FOLL_LONGTERM must only be set internally by the
> > +	 * pin_user_page*() and pin_longterm_*() APIs, never directly by the
> > +	 * caller, so enforce that with an assertion:
> >   	 */
> > -	if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
> > +	if (WARN_ON_ONCE(gup_flags & (FOLL_PIN | FOLL_LONGTERM)))
>
> Don't we want to block FOLL_LONGTERM in get_user_pages_fast() as well after all
> this?

Yes. But with the latest idea to restore FOLL_LONGTERM to its original glory,
that won't be an issue in the next version. heh.


thanks,
--
John Hubbard
NVIDIA