Subject: memcontrol: try charging huge pages from stock

From: Johannes Weiner <hannes@cmpxchg.org>

The stock unit is just bytes, there is no reason to only take normal
pages from it.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index fdc7e1a..41a8cbd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1469,19 +1469,19 @@ static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
 static atomic_t memcg_drain_count;
 
 /*
- * Try to consume stocked charge on this cpu. If success, PAGE_SIZE is consumed
+ * Try to consume stocked charge on this cpu. If success, @val is consumed
  * from local stock and true is returned. If the stock is 0 or charges from a
  * cgroup which is not current target, returns false. This stock will be
  * refilled.
  */
-static bool consume_stock(struct mem_cgroup *mem)
+static bool consume_stock(struct mem_cgroup *mem, int val)
 {
 	struct memcg_stock_pcp *stock;
 	bool ret = true;
 
 	stock = &get_cpu_var(memcg_stock);
-	if (mem == stock->cached && stock->charge)
-		stock->charge -= PAGE_SIZE;
+	if (mem == stock->cached && stock->charge >= val)
+		stock->charge -= val;
 	else /* need to call res_counter_charge */
 		ret = false;
 	put_cpu_var(memcg_stock);
@@ -1629,9 +1629,8 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
 		int ret = 0;
 		unsigned long flags = 0;
 
-		if (page_size == PAGE_SIZE)
-			if (consume_stock(mem))
-				goto done;
+		if (consume_stock(mem, page_size))
+			goto done;
 
 		ret = res_counter_charge(&mem->res, csize, &fail_res);
 		if (likely(!ret)) {