[PATCH V2] mm: fix potential pte_unmap_unlock pte error

[Shijie Luo]

When flags don't have MPOL_MF_MOVE or MPOL_MF_MOVE_ALL bits, code breaks
 and passing origin pte - 1 to pte_unmap_unlock seems like not a good idea.

Signed-off-by: Shijie Luo <luoshij...@huawei.com>
Signed-off-by: Michal Hocko <mho...@suse.com>
Signed-off-by: Miaohe Lin <linmia...@huawei.com>
---
 mm/mempolicy.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3fde772ef5ef..3ca4898f3f24 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -525,7 +525,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long 
addr,
        unsigned long flags = qp->flags;
        int ret;
        bool has_unmovable = false;
-       pte_t *pte;
+       pte_t *pte, *mapped_pte;
        spinlock_t *ptl;
 
        ptl = pmd_trans_huge_lock(pmd, vma);
@@ -539,7 +539,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long 
addr,
        if (pmd_trans_unstable(pmd))
                return 0;
 
-       pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+       mapped_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
        for (; addr != end; pte++, addr += PAGE_SIZE) {
                if (!pte_present(*pte))
                        continue;
@@ -571,7 +571,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long 
addr,
                } else
                        break;
        }
-       pte_unmap_unlock(pte - 1, ptl);
+       pte_unmap_unlock(mapped_pte, ptl);
        cond_resched();
 
        if (has_unmovable)
-- 
2.19.1