2 files changed, 31 insertions, 90 deletions

diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index bf1f01bc013f..c9d625ca659e 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -129,20 +129,22 @@ int __must_check res_counter_charge(struct res_counter *counter,
 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
 void res_counter_uncharge(struct res_counter *counter, unsigned long val);
 
-static inline bool res_counter_limit_check_locked(struct res_counter *cnt)
-{
-        if (cnt->usage < cnt->limit)
-                return true;
-
-        return false;
-}
-
-static inline bool res_counter_soft_limit_check_locked(struct res_counter *cnt)
+/**
+ * res_counter_margin - calculate chargeable space of a counter
+ * @cnt: the counter
+ *
+ * Returns the difference between the hard limit and the current usage
+ * of resource counter @cnt.
+ */
+static inline unsigned long long res_counter_margin(struct res_counter *cnt)
 {
-        if (cnt->usage <= cnt->soft_limit)
-                return true;
+        unsigned long long margin;
+        unsigned long flags;
 
-        return false;
+        spin_lock_irqsave(&cnt->lock, flags);
+        margin = cnt->limit - cnt->usage;
+        spin_unlock_irqrestore(&cnt->lock, flags);
+        return margin;
 }
 
 /**
@@ -167,52 +169,6 @@ res_counter_soft_limit_excess(struct res_counter *cnt)
         return excess;
 }
 
-/*
- * Helper function to detect if the cgroup is within it's limit or
- * not. It's currently called from cgroup_rss_prepare()
- */
-static inline bool res_counter_check_under_limit(struct res_counter *cnt)
-{
-        bool ret;
-        unsigned long flags;
-
-        spin_lock_irqsave(&cnt->lock, flags);
-        ret = res_counter_limit_check_locked(cnt);
-        spin_unlock_irqrestore(&cnt->lock, flags);
-        return ret;
-}
-
-/**
- * res_counter_check_margin - check if the counter allows charging
- * @cnt: the resource counter to check
- * @bytes: the number of bytes to check the remaining space against
- *
- * Returns a boolean value on whether the counter can be charged
- * @bytes or whether this would exceed the limit.
- */
-static inline bool res_counter_check_margin(struct res_counter *cnt,
-                                            unsigned long bytes)
-{
-        bool ret;
-        unsigned long flags;
-
-        spin_lock_irqsave(&cnt->lock, flags);
-        ret = cnt->limit - cnt->usage >= bytes;
-        spin_unlock_irqrestore(&cnt->lock, flags);
-        return ret;
-}
-
-static inline bool res_counter_check_within_soft_limit(struct res_counter *cnt)
-{
-        bool ret;
-        unsigned long flags;
-
-        spin_lock_irqsave(&cnt->lock, flags);
-        ret = res_counter_soft_limit_check_locked(cnt);
-        spin_unlock_irqrestore(&cnt->lock, flags);
-        return ret;
-}
-
 static inline void res_counter_reset_max(struct res_counter *cnt)
 {
         unsigned long flags;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 13de53fe0108..62bbb48980e5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -504,11 +504,6 @@ static void mem_cgroup_remove_from_trees(struct mem_cgroup *mem)
         }
 }
 
-static inline unsigned long mem_cgroup_get_excess(struct mem_cgroup *mem)
-{
-        return res_counter_soft_limit_excess(&mem->res) >> PAGE_SHIFT;
-}
-
 static struct mem_cgroup_per_zone *
 __mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
 {
@@ -1127,33 +1122,21 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 #define mem_cgroup_from_res_counter(counter, member)    \
         container_of(counter, struct mem_cgroup, member)
 
-static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
-{
-        if (do_swap_account) {
-                if (res_counter_check_under_limit(&mem->res) &&
-                        res_counter_check_under_limit(&mem->memsw))
-                        return true;
-        } else
-                if (res_counter_check_under_limit(&mem->res))
-                        return true;
-        return false;
-}
-
 /**
- * mem_cgroup_check_margin - check if the memory cgroup allows charging
- * @mem: memory cgroup to check
- * @bytes: the number of bytes the caller intends to charge
+ * mem_cgroup_margin - calculate chargeable space of a memory cgroup
+ * @mem: the memory cgroup
  *
- * Returns a boolean value on whether @mem can be charged @bytes or
- * whether this would exceed the limit.
+ * Returns the maximum amount of memory @mem can be charged with, in
+ * bytes.
  */
-static bool mem_cgroup_check_margin(struct mem_cgroup *mem, unsigned long bytes)
+static unsigned long long mem_cgroup_margin(struct mem_cgroup *mem)
 {
-        if (!res_counter_check_margin(&mem->res, bytes))
-                return false;
-        if (do_swap_account && !res_counter_check_margin(&mem->memsw, bytes))
-                return false;
-        return true;
+        unsigned long long margin;
+
+        margin = res_counter_margin(&mem->res);
+        if (do_swap_account)
+                margin = min(margin, res_counter_margin(&mem->memsw));
+        return margin;
 }
 
 static unsigned int get_swappiness(struct mem_cgroup *memcg)
@@ -1420,7 +1403,9 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
         bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP;
         bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
         bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
-        unsigned long excess = mem_cgroup_get_excess(root_mem);
+        unsigned long excess;
+
+        excess = res_counter_soft_limit_excess(&root_mem->res) >> PAGE_SHIFT;
 
         /* If memsw_is_minimum==1, swap-out is of-no-use. */
         if (root_mem->memsw_is_minimum)
@@ -1477,9 +1462,9 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
                         return ret;
                 total += ret;
                 if (check_soft) {
-                        if (res_counter_check_within_soft_limit(&root_mem->res))
+                        if (!res_counter_soft_limit_excess(&root_mem->res))
                                 return total;
-                } else if (mem_cgroup_check_under_limit(root_mem))
+                } else if (mem_cgroup_margin(root_mem))
                         return 1 + total;
         }
         return total;
@@ -1898,7 +1883,7 @@ static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
 
         ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
                                               gfp_mask, flags);
-        if (mem_cgroup_check_margin(mem_over_limit, csize))
+        if (mem_cgroup_margin(mem_over_limit) >= csize)
                 return CHARGE_RETRY;
         /*
          * Even though the limit is exceeded at this point, reclaim