diff mbox series

[v2,06/10] mm/hugetlb: Make hugetlb_follow_page_mask() safe to pmd unshare

Message ID 20221207203034.650899-7-peterx@redhat.com (mailing list archive)
State New
Headers show
Series [v2,01/10] mm/hugetlb: Let vma_offset_start() to return start | expand

Commit Message

Peter Xu Dec. 7, 2022, 8:30 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>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 mm/hugetlb.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

John Hubbard Dec. 7, 2022, 11:21 p.m. UTC | #1 
On 12/7/22 12:30, Peter Xu wrote:
> 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>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>   mm/hugetlb.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)

Reviewed-by: John Hubbard <jhubbard@nvidia.com>


thanks,
diff mbox series

Patch

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 49f73677a418..3fbbd599d015 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6226,9 +6226,10 @@  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);
@@ -6251,6 +6252,8 @@  struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
 	}
 out:
 	spin_unlock(ptl);
+out_unlock:
+	hugetlb_vma_unlock_read(vma);
 	return page;
 }