---

yaml --- r: 198239 b: refs/heads/master c: 67b9509 h: refs/heads/master i: 198237: 5a639ab 198235: b85fa9c 198231: 0b70a64 198223: a6ae2c7 198207: 8996e92 v: v3
git-mirror · May 25, 2010 · d83e277 · d83e277
1 parent b45f90c
commit d83e277
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Showing 2 changed files with 12 additions and 1 deletion.
diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7f60c214fd3a360461f3286c6908084f7f8b1950
+refs/heads/master: 67b9509b2c68ae38cecb83a239881cb0ddf087dc
diff --git a/trunk/mm/migrate.c b/trunk/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);
 	}