Re: [PATCH 06/64] mm: teach pagefault paths about range locking

[Davidlohr Bueso]

On Mon, 05 Feb 2018, Laurent Dufour wrote:

> > --- a/drivers/misc/sgi-gru/grufault.c
> > +++ b/drivers/misc/sgi-gru/grufault.c
> > @@ -189,7 +189,8 @@ static void get_clear_fault_map(struct gru_state *gru,
> >   */
> >  static int non_atomic_pte_lookup(struct vm_area_struct *vma,
> >  				 unsigned long vaddr, int write,
> > -				 unsigned long *paddr, int *pageshift)
> > +				 unsigned long *paddr, int *pageshift,
> > +				 struct range_lock *mmrange)
> >  {
> >  	struct page *page;
> >
> > @@ -198,7 +199,8 @@ static int non_atomic_pte_lookup(struct vm_area_struct *vma,
> >  #else
> >  	*pageshift = PAGE_SHIFT;
> >  #endif
> > -	if (get_user_pages(vaddr, 1, write ? FOLL_WRITE : 0, &page, NULL) <= 0)
> > +	if (get_user_pages(vaddr, 1, write ? FOLL_WRITE : 0,
> > +			   &page, NULL, mmrange) <= 0)
>
> There is no need to pass down the range here since underlying called
> __get_user_pages_locked() is told to not unlock the mmap_sem.
> In general get_user_pages() doesn't need a range parameter.

Yeah, you're right. At least it was a productive exercise for auditing.

Thanks,
Davidlohr