memcg: create extensible page stat update routines

Replace usage of the mem_cgroup_update_file_mapped() memcg
statistic update routine with two new routines:
* mem_cgroup_inc_page_stat()
* mem_cgroup_dec_page_stat()

As before, only the file_mapped statistic is managed.  However, these more
general interfaces allow for new statistics to be more easily added.  New
statistics are added with memcg dirty page accounting.

Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrea Righi <arighi@develer.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 28 insertions, 3 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)
 {
 }