thp: split_huge_page_mm/vma

split_huge_page_pmd compat code.  Each one of those would need to be
expanded to hundred of lines of complex code without a fully reliable
split_huge_page_pmd design.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mremap.c b/mm/mremap.c
index b09eefa..9925b63 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -41,6 +41,7 @@
 		return NULL;
 
 	pmd = pmd_offset(pud, addr);
+	split_huge_page_pmd(mm, pmd);
 	if (pmd_none_or_clear_bad(pmd))
 		return NULL;