1 files changed, 10 insertions, 15 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index a805474df4ab..56e6069d2452 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -97,6 +97,11 @@ enum mem_cgroup_events_target {
 #define MEM_CGROUP_ID_SHIFT     16
 #define MEM_CGROUP_ID_MAX       USHRT_MAX
 
+struct mem_cgroup_id {
+        int id;
+        atomic_t ref;
+};
+
 struct mem_cgroup_stat_cpu {
         long count[MEMCG_NR_STAT];
         unsigned long events[MEMCG_NR_EVENTS];
@@ -172,6 +177,9 @@ enum memcg_kmem_state {
 struct mem_cgroup {
         struct cgroup_subsys_state css;
 
+        /* Private memcg ID. Used to ID objects that outlive the cgroup */
+        struct mem_cgroup_id id;
+
         /* Accounted resources */
         struct page_counter memory;
         struct page_counter swap;
@@ -330,22 +338,9 @@ static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
         if (mem_cgroup_disabled())
                 return 0;
 
-        return memcg->css.id;
-}
-
-/**
- * mem_cgroup_from_id - look up a memcg from an id
- * @id: the id to look up
- *
- * Caller must hold rcu_read_lock() and use css_tryget() as necessary.
- */
-static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
-{
-        struct cgroup_subsys_state *css;
-
-        css = css_from_id(id, &memory_cgrp_subsys);
-        return mem_cgroup_from_css(css);
+        return memcg->id.id;
 }
+struct mem_cgroup *mem_cgroup_from_id(unsigned short id);
 
 /**
  * parent_mem_cgroup - find the accounting parent of a memcg