mm/hugetlb: check for pte NULL pointer in __page_check_address()

In __page_check_address(), if address's pud is not present,
huge_pte_offset() will return NULL, we should check the return value.

Signed-off-by: Jianguo Wu <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: qiuxishi <[email protected]>
Cc: Hanjun Guo <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/mm/rmap.c b/mm/rmap.c
index 55c8b8dc9ffb0c349eb63ad20a8d7bbcc2e9b25d..068522d8502a58e9465a963e68c37ce4ccf635d7 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -600,7 +600,11 @@ pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
        spinlock_t *ptl;
 
        if (unlikely(PageHuge(page))) {
+               /* when pud is not present, pte will be NULL */
                pte = huge_pte_offset(mm, address);
+               if (!pte)
+                       return NULL;
+
                ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
                goto check;
        }