path: root/mm/ksm.c
diff options
authorHugh Dickins <hughd@google.com>2011-01-13 15:47:29 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 17:32:49 -0800
commit2919bfd0758257c469abef8c26c3e516bbebb851 (patch)
tree093244c121dcbb91423f119cea9abc50e11ad078 /mm/ksm.c
parenthugetlb: fix handling of parse errors in sysfs (diff)
ksm: drain pagevecs to lru
It was hard to explain the page counts which were causing new LTP tests of KSM to fail: we need to drain the per-cpu pagevecs to LRU occasionally. Signed-off-by: Hugh Dickins <hughd@google.com> Reported-by: CAI Qian <caiqian@redhat.com> Cc:Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
1 files changed, 12 insertions, 0 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index 33781de0b6bf..c2b2a94f9d67 100644
--- a/mm/ksm.c
+++ b/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;