1 files changed, 57 insertions, 4 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 20e1d90b3363..886e2224c5fd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -149,6 +149,10 @@ struct mem_cgroup {
 	 * reclaimed from. Protected by cgroup_lock()
 	 */
 	struct mem_cgroup *last_scanned_child;
+	/*
+	 * Should the accounting and control be hierarchical, per subtree?
+	 */
+	bool use_hierarchy;
 
 	int		obsolete;
 	atomic_t	refcnt;
@@ -1543,6 +1547,44 @@ int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
 }
 
 
+static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
+{
+	return mem_cgroup_from_cont(cont)->use_hierarchy;
+}
+
+static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
+					u64 val)
+{
+	int retval = 0;
+	struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
+	struct cgroup *parent = cont->parent;
+	struct mem_cgroup *parent_mem = NULL;
+
+	if (parent)
+		parent_mem = mem_cgroup_from_cont(parent);
+
+	cgroup_lock();
+	/*
+	 * If parent's use_hiearchy is set, we can't make any modifications
+	 * in the child subtrees. If it is unset, then the change can
+	 * occur, provided the current cgroup has no children.
+	 *
+	 * For the root cgroup, parent_mem is NULL, we allow value to be
+	 * set if there are no children.
+	 */
+	if ((!parent_mem || !parent_mem->use_hierarchy) &&
+				(val == 1 || val == 0)) {
+		if (list_empty(&cont->children))
+			mem->use_hierarchy = val;
+		else
+			retval = -EBUSY;
+	} else
+		retval = -EINVAL;
+	cgroup_unlock();
+
+	return retval;
+}
+
 static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
 {
 	struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
@@ -1706,6 +1748,11 @@ static struct cftype mem_cgroup_files[] = {
 		.name = "force_empty",
 		.trigger = mem_cgroup_force_empty_write,
 	},
+	{
+		.name = "use_hierarchy",
+		.write_u64 = mem_cgroup_hierarchy_write,
+		.read_u64 = mem_cgroup_hierarchy_read,
+	},
 };
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
@@ -1881,12 +1928,18 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 	if (cont->parent == NULL) {
 		enable_swap_cgroup();
 		parent = NULL;
-	} else
+	} else {
 		parent = mem_cgroup_from_cont(cont->parent);
+		mem->use_hierarchy = parent->use_hierarchy;
+	}
 
-	res_counter_init(&mem->res, parent ? &parent->res : NULL);
-	res_counter_init(&mem->memsw, parent ? &parent->memsw : NULL);
-
+	if (parent && parent->use_hierarchy) {
+		res_counter_init(&mem->res, &parent->res);
+		res_counter_init(&mem->memsw, &parent->memsw);
+	} else {
+		res_counter_init(&mem->res, NULL);
+		res_counter_init(&mem->memsw, NULL);
+	}
 
 	mem->last_scanned_child = NULL;