memcg requires the cgroup id to be smaller than 65536.
This is a preparation to kill css id.
Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
---
mm/memcontrol.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6719e2c..4e40ebe 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -498,6 +498,12 @@ 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)
{
/*
@@ -6312,6 +6318,9 @@ 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;
--
1.8.0.2
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