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 <riel@redhat.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 892d8a17a7e5..f4f6041176a4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1143,6 +1143,7 @@ static void __split_huge_page_refcount(struct page *page)
         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);
@@ -1207,6 +1208,15 @@ static void __split_huge_page_refcount(struct page *page)
         __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);
         spin_unlock_irq(&zone->lru_lock);