Messages in this thread Patch in this message | | | From | Peter Xu <> | Subject | [PATCH v4 6/9] mm/hugetlb: Make hugetlb_follow_page_mask() safe to pmd unshare | Date | Fri, 16 Dec 2022 10:52:19 -0500 |
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Since hugetlb_follow_page_mask() walks the pgtable, it needs the vma lock to make sure the pgtable page will not be freed concurrently.
Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Peter Xu <peterx@redhat.com> --- mm/hugetlb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 64512a151567..0bf0abea388d 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6375,9 +6375,10 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, if (WARN_ON_ONCE(flags & FOLL_PIN)) return NULL; + hugetlb_vma_lock_read(vma); pte = huge_pte_offset(mm, haddr, huge_page_size(h)); if (!pte) - return NULL; + goto out_unlock; ptl = huge_pte_lock(h, mm, pte); entry = huge_ptep_get(pte); @@ -6400,6 +6401,8 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, } out: spin_unlock(ptl); +out_unlock: + hugetlb_vma_unlock_read(vma); return page; } -- 2.37.3
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