memcg: allocate memory cgroup structures in local nodes

Commit dde79e00 ("page_cgroup: reduce allocation overhead for
page_cgroup array for CONFIG_SPARSEMEM") added a regression that the
memory cgroup data structures all end up in node 0 because the first
attempt at allocating them would not pass in a node hint.  Since the
initialization runs on CPU #0 it would all end up node 0.  This is a
problem on large memory systems, where node 0 would lose a lot of
memory.

Change the alloc_pages_exact() to alloc_pages_exact_nid().  This will
still fall back to other nodes if not enough memory is available.

 [ RED-PEN: right now it would fall back first before trying
   vmalloc_node.  Probably not the best strategy ...  But I left it like
   that for now. ]

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Reported-by: Doug Nelson
Cc: David Rientjes <rientjes@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>