mm, page_owner: handle THP splits correctly

THP splitting path is missing the split_page_owner() call that
split_page() has.

As a result, split THP pages are wrongly reported in the page_owner file
as order-9 pages.  Furthermore when the former head page is freed, the
remaining former tail pages are not listed in the page_owner file at
all.  This patch fixes that by adding the split_page_owner() call into
__split_huge_page().

Link: http://lkml.kernel.org/r/[email protected]
Fixes: a9627bc ("mm/page_owner: introduce split_page_owner and replace manual handling")
Reported-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Vlastimil Babka <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/huge_memory.c

@@ -32,6 +32,7 @@
 #include <linux/shmem_fs.h>
 #include <linux/oom.h>
 #include <linux/numa.h>
+#include <linux/page_owner.h>
 
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
@@ -2516,6 +2517,9 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 	}
 
 	ClearPageCompound(head);
+
+	split_page_owner(head, HPAGE_PMD_ORDER);
+
 	/* See comment in __split_huge_page_tail() */
 	if (PageAnon(head)) {
 		/* Additional pin to swap cache */