hugetlb/cgroup: migrate hugetlb cgroup info from oldpage to new page during migration

hugetlb/cgroup: migrate hugetlb cgroup info from oldpage to new page during migration

With HugeTLB pages, hugetlb cgroup is uncharged in compound page
destructor.  Since we are holding a hugepage reference, we can be sure
that old page won't get uncharged till the last put_page().

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>