mm-hugetlbfs-fix-rmapping-for-anonymous-hugepages-with-page_pgoff-v3

mm-hugetlbfs-fix-rmapping-for-anonymous-hugepages-with-page_pgoff-v3

- add comment on page_size_order()
- use compound_order(compound_head(page)) instead of huge_page_size_order()
- use page_pgoff() in rmap_walk_file() too
- use page_size_order() in kill_proc()
- fix space indent

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>