3 files changed, 37 insertions, 14 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 159a0762aeaf..067115ce6b3e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -25,6 +25,11 @@ struct page_cgroup;
 struct page;
 struct mm_struct;
 
+/* Stats that can be updated by kernel. */
+enum mem_cgroup_page_stat_item {
+        MEMCG_NR_FILE_MAPPED, /* # of pages charged as file rss */
+};
+
 extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
                                         struct list_head *dst,
                                         unsigned long *scanned, int order,
@@ -121,7 +126,22 @@ static inline bool mem_cgroup_disabled(void)
         return false;
 }
 
-void mem_cgroup_update_file_mapped(struct page *page, int val);
+void mem_cgroup_update_page_stat(struct page *page,
+                                 enum mem_cgroup_page_stat_item idx,
+                                 int val);
+
+static inline void mem_cgroup_inc_page_stat(struct page *page,
+                                            enum mem_cgroup_page_stat_item idx)
+{
+        mem_cgroup_update_page_stat(page, idx, 1);
+}
+
+static inline void mem_cgroup_dec_page_stat(struct page *page,
+                                            enum mem_cgroup_page_stat_item idx)
+{
+        mem_cgroup_update_page_stat(page, idx, -1);
+}
+
 unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
                                                 gfp_t gfp_mask);
 u64 mem_cgroup_get_limit(struct mem_cgroup *mem);
@@ -293,8 +313,13 @@ mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
 {
 }
 
-static inline void mem_cgroup_update_file_mapped(struct page *page,
-                                                        int val)
+static inline void mem_cgroup_inc_page_stat(struct page *page,
+                                            enum mem_cgroup_page_stat_item idx)
+{
+}
+
+static inline void mem_cgroup_dec_page_stat(struct page *page,
+                                            enum mem_cgroup_page_stat_item idx)
 {
 }
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 741206ffdace..3d8a0c79dece 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1600,7 +1600,8 @@ bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask)
  * possibility of race condition. If there is, we take a lock.
  */
 
-static void mem_cgroup_update_file_stat(struct page *page, int idx, int val)
+void mem_cgroup_update_page_stat(struct page *page,
+                                 enum mem_cgroup_page_stat_item idx, int val)
 {
         struct mem_cgroup *mem;
         struct page_cgroup *pc = lookup_page_cgroup(page);
@@ -1623,30 +1624,27 @@ static void mem_cgroup_update_file_stat(struct page *page, int idx, int val)
                         goto out;
         }
 
-        this_cpu_add(mem->stat->count[idx], val);
-
         switch (idx) {
-        case MEM_CGROUP_STAT_FILE_MAPPED:
+        case MEMCG_NR_FILE_MAPPED:
                 if (val > 0)
                         SetPageCgroupFileMapped(pc);
                 else if (!page_mapped(page))
                         ClearPageCgroupFileMapped(pc);
+                idx = MEM_CGROUP_STAT_FILE_MAPPED;
                 break;
         default:
                 BUG();
         }
 
+        this_cpu_add(mem->stat->count[idx], val);
+
 out:
         if (unlikely(need_unlock))
                 unlock_page_cgroup(pc);
         rcu_read_unlock();
         return;
 }
-
-void mem_cgroup_update_file_mapped(struct page *page, int val)
-{
-        mem_cgroup_update_file_stat(page, MEM_CGROUP_STAT_FILE_MAPPED, val);
-}
+EXPORT_SYMBOL(mem_cgroup_update_page_stat);
 
 /*
  * size of first charge trial. "32" comes from vmscan.c's magic value.
diff --git a/mm/rmap.c b/mm/rmap.c
index c30f33854f97..f21f4a1d6a1c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -937,7 +937,7 @@ void page_add_file_rmap(struct page *page)
 {
         if (atomic_inc_and_test(&page->_mapcount)) {
                 __inc_zone_page_state(page, NR_FILE_MAPPED);
-                mem_cgroup_update_file_mapped(page, 1);
+                mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED);
         }
 }
 
@@ -979,7 +979,7 @@ void page_remove_rmap(struct page *page)
                                               NR_ANON_TRANSPARENT_HUGEPAGES);
         } else {
                 __dec_zone_page_state(page, NR_FILE_MAPPED);
-                mem_cgroup_update_file_mapped(page, -1);
+                mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED);
         }
         /*
          * It would be tidy to reset the PageAnon mapping here,