From 4219b2da206b3787dea4950ec53ccbc203f50e5e Mon Sep 17 00:00:00 2001
From: Li Zefan <lizefan@huawei.com>
Date: Mon, 23 Sep 2013 16:56:29 +0800
Subject: [PATCH] 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 <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
mm/memcontrol.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 404a13a09efa..c14039575608 100644
--- 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;
--
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