diff options
| -rw-r--r-- | mm/migrate.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 42a3d24d110..b114635962d 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -600,6 +600,17 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, if (PageAnon(page)) { rcu_read_lock(); rcu_locked = 1; + + /* + * If the page has no mappings any more, just bail. An + * unmapped anon page is likely to be freed soon but worse, + * it's possible its anon_vma disappeared between when + * the page was isolated and when we reached here while + * the RCU lock was not held + */ + if (!page_mapped(page)) + goto rcu_unlock; + anon_vma = page_anon_vma(page); atomic_inc(&anon_vma->external_refcount); } |