diff --git a/[refs] b/[refs]
index 0ea4a532319c..c86d833bfffb 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 73ae31e5986a4c0ee84bfd13ccd9b57a98956f6f
+refs/heads/master: 2919bfd0758257c469abef8c26c3e516bbebb851
diff --git a/trunk/mm/ksm.c b/trunk/mm/ksm.c
index 33781de0b6bf..c2b2a94f9d67 100644
--- a/trunk/mm/ksm.c
+++ b/trunk/mm/ksm.c
@@ -1296,6 +1296,18 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
 
 	slot = ksm_scan.mm_slot;
 	if (slot == &ksm_mm_head) {
+		/*
+		 * A number of pages can hang around indefinitely on per-cpu
+		 * pagevecs, raised page count preventing write_protect_page
+		 * from merging them.  Though it doesn't really matter much,
+		 * it is puzzling to see some stuck in pages_volatile until
+		 * other activity jostles them out, and they also prevented
+		 * LTP's KSM test from succeeding deterministically; so drain
+		 * them here (here rather than on entry to ksm_do_scan(),
+		 * so we don't IPI too often when pages_to_scan is set low).
+		 */
+		lru_add_drain_all();
+
 		root_unstable_tree = RB_ROOT;
 
 		spin_lock(&ksm_mmlist_lock);