Hello, Michal.

On Tue, Sep 11, 2012 at 12:04:33PM +0200, Michal Hocko wrote:

quoted

 	cgroup_unlock();

@@ -4953,6 +4958,7 @@ mem_cgroup_create(struct cgroup *cont)
 						&per_cpu(memcg_stock, cpu);
 			INIT_WORK(&stock->work, drain_local_stock);
 		}
+		mem_cgroup_subsys.broken_hierarchy = !memcg->use_hierarchy;

Hmmm, this will warn even if we have
root (default use_hierarchy=0)
 \
  A (use_hierarchy=1)
   \
    B <- here

which is unfortunate because it will add a noise to a reasonable
configuration.

I suppose you're talking about having root group not performing any
accounting and/or control?  I suppose such could be a valid use case
(is it really necessary tho?)  but I don't think .use_hierarchy is the
right interface for that.  If it's absolutely necessary, I think it
should be a root-only flag (even if that ends up using the same code
path).  Eventually, we really want to kill .use_hierarchy, or at least
make it to RO 1.  As it's currently defined, it's just way too
confusing.

quoted

 		hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
 	} else {
 		parent = mem_cgroup_from_cont(cont->parent);

--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c

@@ -330,7 +330,17 @@ struct cgroup_subsys net_prio_subsys = {
 	.subsys_id	= net_prio_subsys_id,
 #endif
 	.base_cftypes	= ss_files,
-	.module		= THIS_MODULE
+	.module		= THIS_MODULE,
+
+	/*
+	 * net_prio has artificial limit on the number of cgroups and
+	 * disallows nesting making it impossible to co-mount it with other
+	 * hierarchical subsystems.  Remove the artificially low PRIOIDX_SZ
+	 * limit and properly nest configuration such that children follow
+	 * their parents' configurations by default and are allowed to
+	 * override and remove the following.
+	 */
+	.broken_hierarchy = trye,

typo

Heh, I thought I enabled all controllers.  Thanks. :)

-- 
tejun