mm: fix race between mremap and removing migration entry

[pandora-kernel.git] / mm / migrate.c

diff --git a/mm/migrate.c b/mm/migrate.c
index 666e4e6..14d0a6a 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -120,10 +120,10 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
 
                ptep = pte_offset_map(pmd, addr);
 
-               if (!is_swap_pte(*ptep)) {
-                       pte_unmap(ptep);
-                       goto out;
-               }
+               /*
+                * Peek to check is_swap_pte() before taking ptlock?  No, we
+                * can race mremap's move_ptes(), which skips anon_vma lock.
+                */
 
                ptl = pte_lockptr(mm, pmd);
        }