Merge tag 'at91-fixes' of git://github.com/at91linux/linux-at91 into fixes

[cascardo/linux.git] / mm / rmap.c

diff --git a/mm/rmap.c b/mm/rmap.c
index bf05fc8..b7e94eb 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -569,6 +569,7 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd = NULL;
+       pmd_t pmde;
 
        pgd = pgd_offset(mm, address);
        if (!pgd_present(*pgd))
@@ -579,7 +580,13 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
                goto out;
 
        pmd = pmd_offset(pud, address);
-       if (!pmd_present(*pmd))
+       /*
+        * Some THP functions use the sequence pmdp_clear_flush(), set_pmd_at()
+        * without holding anon_vma lock for write.  So when looking for a
+        * genuine pmde (in which to find pte), test present and !THP together.
+        */
+       pmde = ACCESS_ONCE(*pmd);
+       if (!pmd_present(pmde) || pmd_trans_huge(pmde))
                pmd = NULL;
 out:
        return pmd;
@@ -615,9 +622,6 @@ pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
        if (!pmd)
                return NULL;
 
-       if (pmd_trans_huge(*pmd))
-               return NULL;
-
        pte = pte_offset_map(pmd, address);
        /* Make a quick check before getting the lock */
        if (!sync && !pte_present(*pte)) {