mm/hugetlb: set head flag before setting compound_order in __prep_compound_gigantic_folio

folio_set_compound_order() checks if the passed in folio is a large folio.
A large folio is indicated by the PG_head flag.  Call __folio_set_head()
before setting the order.

Link: https://lkml.kernel.org/r/20221212225529.22493-1-sidhartha.kumar@oracle.com
Fixes: d1c6095 ("mm/hugetlb: convert hugetlb prep functions to folios")
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reported-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Sidhartha Kumar

mm/hugetlb.c

@@ -1805,10 +1805,10 @@ static bool __prep_compound_gigantic_folio(struct folio *folio,
 	int nr_pages = 1 << order;
 	struct page *p;
 
-	/* we rely on prep_new_hugetlb_folio to set the destructor */
-	folio_set_compound_order(folio, order);
 	__folio_clear_reserved(folio);
 	__folio_set_head(folio);
+	/* we rely on prep_new_hugetlb_folio to set the destructor */
+	folio_set_compound_order(folio, order);
 	for (i = 0; i < nr_pages; i++) {
 		p = folio_page(folio, i);