On Tue, Jun 20, 2023 at 05:23:09PM +0200, David Hildenbrand wrote:
> On 20.06.23 01:10, Peter Xu wrote:
> > follow_page() doesn't need it, but we'll start to need it when unifying gup
> > for hugetlb.
> >
> > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
> > ---
> > include/linux/hugetlb.h | 8 +++++---
> > mm/gup.c | 3 ++-
> > mm/hugetlb.c | 5 ++++-
> > 3 files changed, 11 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> > index beb7c63d2871..2e2d89e79d6c 100644
> > --- a/include/linux/hugetlb.h
> > +++ b/include/linux/hugetlb.h
> > @@ -131,7 +131,8 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
> > int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *,
> > struct vm_area_struct *, struct vm_area_struct *);
> > struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
> > - unsigned long address, unsigned int flags);
> > + unsigned long address, unsigned int flags,
> > + unsigned int *page_mask);
> > long follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *,
> > struct page **, unsigned long *, unsigned long *,
> > long, unsigned int, int *);
> > @@ -297,8 +298,9 @@ static inline void adjust_range_if_pmd_sharing_possible(
> > {
> > }
> > -static inline struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
> > - unsigned long address, unsigned int flags)
> > +static inline struct page *hugetlb_follow_page_mask(
> > + struct vm_area_struct *vma, unsigned long address, unsigned int flags,
> > + unsigned int *page_mask)
> > {
> > BUILD_BUG(); /* should never be compiled in if !CONFIG_HUGETLB_PAGE*/
> > }
> > diff --git a/mm/gup.c b/mm/gup.c
> > index abcd841d94b7..9fc9271cba8d 100644
> > --- a/mm/gup.c
> > +++ b/mm/gup.c
> > @@ -780,7 +780,8 @@ static struct page *follow_page_mask(struct vm_area_struct *vma,
> > * Ordinary GUP uses follow_hugetlb_page for hugetlb processing.
> > */
> > if (is_vm_hugetlb_page(vma))
> > - return hugetlb_follow_page_mask(vma, address, flags);
> > + return hugetlb_follow_page_mask(vma, address, flags,
> > + &ctx->page_mask);
> > pgd = pgd_offset(mm, address);
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 9a6918c4250a..fbf6a09c0ec4 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -6454,7 +6454,8 @@ static inline bool __follow_hugetlb_must_fault(struct vm_area_struct *vma,
> > }
> > struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
> > - unsigned long address, unsigned int flags)
> > + unsigned long address, unsigned int flags,
> > + unsigned int *page_mask)
> > {
> > struct hstate *h = hstate_vma(vma);
> > struct mm_struct *mm = vma->vm_mm;
> > @@ -6499,6 +6500,8 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
> > page = NULL;
> > goto out;
> > }
> > +
> > + *page_mask = ~huge_page_mask(h) >> PAGE_SHIFT;
>
> As discussed, can be simplified. But can be done on top (or not at all, but
> it is confusing code).
Since we decided to make this prettier.. At last I decided to go with this:
*page_mask = (1U << huge_page_order(h)) - 1;
The previous suggestion of PHYS_PFN() will do two shifts over PAGE_SIZE
(the other one in huge_page_size()) which might be unnecessary, also, PHYS_
can be slightly misleading too as prefix.
>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
I'll take this with above change, please shoot if not applicable. Thanks,
--
Peter Xu
