Re: [PATCH v2 15/46] hugetlb: add make_huge_pte_with_shift

[Mina Almasry]

On Fri, Feb 17, 2023 at 4:28 PM James Houghton <jthoughton@xxxxxxxxxx> wrote:
>
> This allows us to make huge PTEs at shifts other than the hstate shift,
> which will be necessary for high-granularity mappings.
>
> Acked-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
>

Reviewed-by: Mina Almasry <almasrymina@xxxxxxxxxx>

> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index f74183acc521..ed1d806020de 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -5110,11 +5110,11 @@ const struct vm_operations_struct hugetlb_vm_ops = {
>         .pagesize = hugetlb_vm_op_pagesize,
>  };
>
> -static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
> -                               int writable)
> +static pte_t make_huge_pte_with_shift(struct vm_area_struct *vma,
> +                                     struct page *page, int writable,
> +                                     int shift)

Nit: can this be 'unsigned int shift'. Because you're actually passing
it an unsigned int below and there is an implicit cast there. Yes it
will never matter, I know...

>  {
>         pte_t entry;
> -       unsigned int shift = huge_page_shift(hstate_vma(vma));
>
>         if (writable) {
>                 entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_pte(page,
> @@ -5128,6 +5128,14 @@ static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
>         return entry;
>  }
>
> +static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
> +                          int writable)
> +{
> +       unsigned int shift = huge_page_shift(hstate_vma(vma));
> +
> +       return make_huge_pte_with_shift(vma, page, writable, shift);
> +}
> +
>  static void set_huge_ptep_writable(struct vm_area_struct *vma,
>                                    unsigned long address, pte_t *ptep)
>  {
> --
> 2.39.2.637.g21b0678d19-goog
>