> On Feb 21, 2020, at 10:34 PM, Longpeng(Mike) <longpeng2@xxxxxxxxxx> wrote:
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index dd8737a..90daf37 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -4910,28 +4910,30 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
> {
> pgd_t *pgd;
> p4d_t *p4d;
> - pud_t *pud;
> - pmd_t *pmd;
> + pud_t *pud, pud_entry;
> + pmd_t *pmd, pmd_entry;
>
> pgd = pgd_offset(mm, addr);
> - if (!pgd_present(*pgd))
> + if (!pgd_present(READ_ONCE(*pgd)))
> return NULL;
> p4d = p4d_offset(pgd, addr);
> - if (!p4d_present(*p4d))
> + if (!p4d_present(READ_ONCE(*p4d)))
> return NULL;
What’s the point of READ_ONCE() on those two places?
