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Commit 2919bfd0 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
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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: default avatarHugh Dickins <hughd@google.com>
Reported-by: default avatarCAI Qian <caiqian@redhat.com>
Cc:Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 73ae31e5

mm/ksm.c

+12 −0
Original line number Diff line number Diff line
@@ -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);