From mboxrd@z Thu Jan  1 00:00:00 1970
From: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
Subject: Re: [PATCH v4 cgroup/for-3.7] cgroup: mark subsystems with broken
	hierarchy support and whine if cgroups are nested for them
Date: Fri, 14 Sep 2012 13:14:54 +0400
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To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Neil Horman <nhorman-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org>, "Serge E. Hallyn" <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>, Paul Mackerras <paulus-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>, "Aneesh Kumar K.V" <aneesh.kumar-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, Arnaldo Carvalho de Melo <acme-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Thomas Graf <tgraf-G/eBtMaohhA@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Paul Turner <pjt-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

On 09/14/2012 12:03 AM, Tejun Heo wrote:
> Hello, Vivek.
> 
> On Thu, Sep 13, 2012 at 03:41:11PM -0400, Vivek Goyal wrote:
>> I think for blkio controller, first level of creation itself is wrong if
>> hierarchy is not supported. 
>>
>> 				root
>> 			       / | \ 
>>                               T1 T2 G1
>>

I side with Vivek, and I think we should warn first level. It just tends
to be wrong. If memcg is a special case, just special case it.
_but_, I see no reason not to do it.

While I agree with Michal point that this is not necessary, I don't
think being noisier than we need to be is a crime. Less noisy certainly
can be.