The patch titled
ksm: drain pagevecs to lru
has been added to the -mm tree. Its filename is
ksm-drain-pagevecs-to-lru.patch
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------------------------------------------------------
Subject: ksm: drain pagevecs to lru
From: Hugh Dickins <hughd@xxxxxxxxxx>
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@xxxxxxxxxx>
Reported-by: CAI Qian <caiqian@xxxxxxxxxx>
Cc:Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff -puN mm/ksm.c~ksm-drain-pagevecs-to-lru mm/ksm.c
--- a/mm/ksm.c~ksm-drain-pagevecs-to-lru
+++ a/mm/ksm.c
@@ -1296,6 +1296,18 @@ static struct rmap_item *scan_get_next_r
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);
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
origin.patch
mm-vmap-area-cache-fix.patch
mm-vmscan-reclaim-order-0-and-use-compaction-instead-of-lumpy-reclaim-avoid-a-potential-deadlock-due-to-lock_page-during-direct-compaction.patch
mm-vmscan-reclaim-order-0-and-use-compaction-instead-of-lumpy-reclaim-avoid-a-potential-deadlock-due-to-lock_page-during-direct-compaction-fix.patch
do_wp_page-remove-the-reuse-flag.patch
do_wp_page-clarify-dirty_page-handling.patch
mlock-avoid-dirtying-pages-and-triggering-writeback.patch
mlock-only-hold-mmap_sem-in-shared-mode-when-faulting-in-pages.patch
mm-add-foll_mlock-follow_page-flag.patch
mm-move-vm_locked-check-to-__mlock_vma_pages_range.patch
mlock-do-not-hold-mmap_sem-for-extended-periods-of-time.patch
mlock-do-not-hold-mmap_sem-for-extended-periods-of-time-fix.patch
thp-ksm-free-swap-when-swapcache-page-is-replaced.patch
thp-transparent-hugepage-core-fixlet.patch
thp-ksm-on-thp.patch
thp-add-compound_trans_head-helper.patch
ksm-drain-pagevecs-to-lru.patch
memcg-fix-memory-migration-of-shmem-swapcache.patch
prio_tree-debugging-patch.patch
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