On Thu, 24 May 2012, Andrew Morton wrote:

These arguments look pretty strong to me.  But poorly timed :(

What I argued here is nothing new, I said the same thing back on April 27 
and I was expecting it to be reproposed as a seperate controller.  The 
counter argument that memcg shouldn't cause a performance degradation 
doesn't hold water: you can't expect every page to be tracked without 
incurring some penalty somewhere.  And it certainly causes ~1% of memory 
to be used up at boot with all the struct page_cgroups.

The counter argument that we'd have to duplicate cgroup setup and 
initialization code from memcg also is irrelevant: all generic cgroup 
mounting, creation, and initialization code should be in kernel/cgroup.c.  
Obviously there will be added code because we're introducing a new cgroup, 
but that's not a reason to force everybody who wants to control hugetlb 
pages to be forced to enable memcg.