memcg: fail to create cgroup if the cgroup id is too big

memcg requires the cgroup id to be smaller than 65536. This is a preparation to kill css id. Signed-off-by: Li Zefan <[email protected]> Acked-by: Michal Hocko <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
lucamilanesio · Sep 24, 2013 · 4219b2d · 4219b2d
1 parent 34c00c3
commit 4219b2d
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
@@ -488,6 +488,12 @@ static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
 	return (memcg == root_mem_cgroup);
 }
 
+/*
+ * We restrict the id in the range of [1, 65535], so it can fit into
+ * an unsigned short.
+ */
+#define MEM_CGROUP_ID_MAX	USHRT_MAX
+
 static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
 {
 	/*
@@ -6059,6 +6065,9 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
 	struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(css));
 	int error = 0;
 
+	if (css->cgroup->id > MEM_CGROUP_ID_MAX)
+		return -ENOSPC;
+
 	if (!parent)
 		return 0;