diff mbox series

[v4,6/9] mm/hugetlb: Make hugetlb_follow_page_mask() safe to pmd unshare

Message ID 20221216155219.2043714-1-peterx@redhat.com (mailing list archive)
State New
Headers show
Series [v4,1/9] mm/hugetlb: Let vma_offset_start() to return start | expand

Commit Message

Peter Xu Dec. 16, 2022, 3:52 p.m. UTC 
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 mbox series

Patch

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;
 }