Subject: scale nr_rotated to balance memory pressure

From: Rik van Riel <riel@redhat.com>

Make sure we scale up nr_rotated when we encounter a referenced
transparent huge page.  This ensures pageout scanning balance
is not distorted when there are huge pages on the LRU.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6da054c..5f794b6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1222,7 +1222,8 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
 			add_page_to_lru_list(zone, page, lru);
 			if (is_active_lru(lru)) {
 				int file = is_file_lru(lru);
-				reclaim_stat->recent_rotated[file]++;
+				int numpages = hpage_nr_pages(page);
+				reclaim_stat->recent_rotated[file] += numpages;
 			}
 			if (!pagevec_add(&pvec, page)) {
 				spin_unlock_irq(&zone->lru_lock);
@@ -1354,7 +1355,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 		}
 
 		if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) {
-			nr_rotated++;
+			nr_rotated += hpage_nr_pages(page);
 			/*
 			 * Identify referenced, file-backed active pages and
 			 * give them one more trip around the active list. So