thp: fix anon memory statistics with transparent hugepages

Count each transparent hugepage as HPAGE_PMD_NR pages in the LRU
statistics, so the Active(anon) and Inactive(anon) statistics in
/proc/meminfo are correct.

Signed-off-by: Rik van Riel <[e-mail]>
Signed-off-by: Andrea Arcangeli <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/huge_mm.h

···
 		return;
 	__vma_adjust_trans_huge(vma, start, end, adjust_next);
 }
+static inline int hpage_nr_pages(struct page *page)
+{
+	if (unlikely(PageTransHuge(page)))
+		return HPAGE_PMD_NR;
+	return 1;
+}
 #else /* CONFIG_TRANSPARENT_HUGEPAGE */
 #define HPAGE_PMD_SHIFT ({ BUG(); 0; })
 #define HPAGE_PMD_MASK ({ BUG(); 0; })
 #define HPAGE_PMD_SIZE ({ BUG(); 0; })
+
+#define hpage_nr_pages(x) 1
 
 #define transparent_hugepage_enabled(__vma) 0
 

include/linux/mm_inline.h

···
 #ifndef LINUX_MM_INLINE_H
 #define LINUX_MM_INLINE_H
 
+#include <linux/huge_mm.h>
+
 /**
  * page_is_file_cache - should the page be on a file LRU or anon LRU?
  * @page: the page to test
···
 		       struct list_head *head)
 {
 	list_add(&page->lru, head);
-	__inc_zone_state(zone, NR_LRU_BASE + l);
+	__mod_zone_page_state(zone, NR_LRU_BASE + l, hpage_nr_pages(page));
 	mem_cgroup_add_lru_list(page, l);
 }
 
···
 del_page_from_lru_list(struct zone *zone, struct page *page, enum lru_list l)
 {
 	list_del(&page->lru);
-	__dec_zone_state(zone, NR_LRU_BASE + l);
+	__mod_zone_page_state(zone, NR_LRU_BASE + l, -hpage_nr_pages(page));
 	mem_cgroup_del_lru_list(page, l);
 }
 
···
 			l += LRU_ACTIVE;
 		}
 	}
-	__dec_zone_state(zone, NR_LRU_BASE + l);
+	__mod_zone_page_state(zone, NR_LRU_BASE + l, -hpage_nr_pages(page));
 	mem_cgroup_del_lru_list(page, l);
 }
 

mm/huge_memory.c

···
 	int i;
 	unsigned long head_index = page->index;
 	struct zone *zone = page_zone(page);
+	int zonestat;
 
 	/* prevent PageLRU to go away from under us, and freeze lru stats */
 	spin_lock_irq(&zone->lru_lock);
···
 
 	__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
 	__mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
+
+	/*
+	 * A hugepage counts for HPAGE_PMD_NR pages on the LRU statistics,
+	 * so adjust those appropriately if this page is on the LRU.
+	 */
+	if (PageLRU(page)) {
+		zonestat = NR_LRU_BASE + page_lru(page);
+		__mod_zone_page_state(zone, zonestat, -(HPAGE_PMD_NR-1));
+	}
 
 	ClearPageCompound(page);
 	compound_unlock(page);

mm/memcontrol.c

···
 		case 0:
 			list_move(&page->lru, dst);
 			mem_cgroup_del_lru(page);
-			nr_taken++;
+			nr_taken += hpage_nr_pages(page);
 			break;
 		case -EBUSY:
 			/* we don't affect global LRU but rotate in our LRU */

mm/vmscan.c

···
 		case 0:
 			list_move(&page->lru, dst);
 			mem_cgroup_del_lru(page);
-			nr_taken++;
+			nr_taken += hpage_nr_pages(page);
 			break;
 
 		case -EBUSY:
···
 			if (__isolate_lru_page(cursor_page, mode, file) == 0) {
 				list_move(&cursor_page->lru, dst);
 				mem_cgroup_del_lru(cursor_page);
-				nr_taken++;
+				nr_taken += hpage_nr_pages(page);
 				nr_lumpy_taken++;
 				if (PageDirty(cursor_page))
 					nr_lumpy_dirty++;
···
 	struct page *page;
 
 	list_for_each_entry(page, page_list, lru) {
+		int numpages = hpage_nr_pages(page);
 		lru = page_lru_base_type(page);
 		if (PageActive(page)) {
 			lru += LRU_ACTIVE;
 			ClearPageActive(page);
-			nr_active++;
+			nr_active += numpages;
 		}
 		if (count)
-			count[lru]++;
+			count[lru] += numpages;
 	}
 
 	return nr_active;
···
 
 		list_move(&page->lru, &zone->lru[lru].list);
 		mem_cgroup_add_lru_list(page, lru);
-		pgmoved++;
+		pgmoved += hpage_nr_pages(page);
 
 		if (!pagevec_add(&pvec, page) || list_empty(list)) {
 			spin_unlock_irq(&zone->lru_lock);