From b398f925208941d6d59fe917780bf8d052ead85a Mon Sep 17 00:00:00 2001 From: Yanuar Harry Date: Sun, 4 Mar 2012 20:22:34 +0700 Subject: [PATCH] ksm: drain pagevecs to lru --- mm/ksm.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/mm/ksm.c b/mm/ksm.c index 5ec8382c..29e824fa 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1268,6 +1268,18 @@ 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);