1 files changed, 18 insertions, 10 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bbfac5063ca..92887b28624 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2060,20 +2060,28 @@ struct memcg_stock_pcp {
 static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
 static DEFINE_MUTEX(percpu_charge_mutex);
 
-/*
- * Try to consume stocked charge on this cpu. If success, one page 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.
+/**
+ * consume_stock: Try to consume stocked charge on this cpu.
+ * @memcg: memcg to consume from.
+ * @nr_pages: how many pages to charge.
+ *
+ * The charges will only happen if @memcg matches the current cpu's memcg
+ * stock, and at least @nr_pages are available in that stock.  Failure to
+ * service an allocation will refill the stock.
+ *
+ * returns true if successful, false otherwise.
  */
-static bool consume_stock(struct mem_cgroup *memcg)
+static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
 {
         struct memcg_stock_pcp *stock;
         bool ret = true;
 
+        if (nr_pages > CHARGE_BATCH)
+                return false;
+
         stock = &get_cpu_var(memcg_stock);
-        if (memcg == stock->cached && stock->nr_pages)
-                stock->nr_pages--;
+        if (memcg == stock->cached && stock->nr_pages >= nr_pages)
+                stock->nr_pages -= nr_pages;
         else /* need to call res_counter_charge */
                 ret = false;
         put_cpu_var(memcg_stock);
@@ -2371,7 +2379,7 @@ again:
                 memcg = *ptr;
                 if (mem_cgroup_is_root(memcg))
                         goto done;
-                if (nr_pages == 1 && consume_stock(memcg))
+                if (consume_stock(memcg, nr_pages))
                         goto done;
                 css_get(&memcg->css);
         } else {
@@ -2396,7 +2404,7 @@ again:
                         rcu_read_unlock();
                         goto done;
                 }
-                if (nr_pages == 1 && consume_stock(memcg)) {
+                if (consume_stock(memcg, nr_pages)) {
                         /*
                          * It seems dagerous to access memcg without css_get().
                          * But considering how consume_stok works, it's not