1 files changed, 12 insertions, 0 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 5938db54e1d7..b768a1d4fa43 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -543,6 +543,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
         int rcu_locked = 0;
         int charge = 0;
         struct mem_cgroup *mem = NULL;
+        struct anon_vma *anon_vma = NULL;
 
         if (!newpage)
                 return -ENOMEM;
@@ -599,6 +600,8 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
         if (PageAnon(page)) {
                 rcu_read_lock();
                 rcu_locked = 1;
+                anon_vma = page_anon_vma(page);
+                atomic_inc(&anon_vma->migrate_refcount);
         }
 
         /*
@@ -638,6 +641,15 @@ skip_unmap:
         if (rc)
                 remove_migration_ptes(page, page);
 rcu_unlock:
+
+        /* Drop an anon_vma reference if we took one */
+        if (anon_vma && atomic_dec_and_lock(&anon_vma->migrate_refcount, &anon_vma->lock)) {
+                int empty = list_empty(&anon_vma->head);
+                spin_unlock(&anon_vma->lock);
+                if (empty)
+                        anon_vma_free(anon_vma);
+        }
+
         if (rcu_locked)
                 rcu_read_unlock();
 uncharge: