On Fri, Jun 24, 2022 at 05:36:41PM +0000, James Houghton wrote:
> This adds it for architectures that use GENERAL_HUGETLB, including x86.
>
> Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
> ---
> include/linux/hugetlb.h | 2 ++
> mm/hugetlb.c | 45 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 47 insertions(+)
>
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index e7a6b944d0cc..605aa19d8572 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -258,6 +258,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
> unsigned long addr, unsigned long sz);
> pte_t *huge_pte_offset(struct mm_struct *mm,
> unsigned long addr, unsigned long sz);
> +int hugetlb_walk_to(struct mm_struct *mm, struct hugetlb_pte *hpte,
> + unsigned long addr, unsigned long sz, bool stop_at_none);
> int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
> unsigned long *addr, pte_t *ptep);
> void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 557b0afdb503..3ec2a921ee6f 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -6981,6 +6981,51 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
> return (pte_t *)pmd;
> }
>
> +int hugetlb_walk_to(struct mm_struct *mm, struct hugetlb_pte *hpte,
> + unsigned long addr, unsigned long sz, bool stop_at_none)
> +{
> + pte_t *ptep;
> +
> + if (!hpte->ptep) {
> + pgd_t *pgd = pgd_offset(mm, addr);
> +
> + if (!pgd)
> + return -ENOMEM;
> + ptep = (pte_t *)p4d_alloc(mm, pgd, addr);
> + if (!ptep)
> + return -ENOMEM;
> + hugetlb_pte_populate(hpte, ptep, P4D_SHIFT);
> + }
> +
> + while (hugetlb_pte_size(hpte) > sz &&
> + !hugetlb_pte_present_leaf(hpte) &&
> + !(stop_at_none && hugetlb_pte_none(hpte))) {
> + if (hpte->shift == PMD_SHIFT) {
> + ptep = pte_alloc_map(mm, (pmd_t *)hpte->ptep, addr);
I had a feeling that the pairing pte_unmap() was lost.
I think most distros are not with CONFIG_HIGHPTE at all, but still..
> + if (!ptep)
> + return -ENOMEM;
> + hpte->shift = PAGE_SHIFT;
> + hpte->ptep = ptep;
> + } else if (hpte->shift == PUD_SHIFT) {
> + ptep = (pte_t *)pmd_alloc(mm, (pud_t *)hpte->ptep,
> + addr);
> + if (!ptep)
> + return -ENOMEM;
> + hpte->shift = PMD_SHIFT;
> + hpte->ptep = ptep;
> + } else if (hpte->shift == P4D_SHIFT) {
> + ptep = (pte_t *)pud_alloc(mm, (p4d_t *)hpte->ptep,
> + addr);
> + if (!ptep)
> + return -ENOMEM;
> + hpte->shift = PUD_SHIFT;
> + hpte->ptep = ptep;
> + } else
> + BUG();
> + }
> + return 0;
> +}
> +
> #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
>
> #ifdef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING
> --
> 2.37.0.rc0.161.g10f37bed90-goog
>
--
Peter Xu
