mm: simplify calling a compound page destructor

None of the three callers of get_compound_page_dtor() want to know the
value; they just want to call the function.  Replace it with
destroy_compound_page() which calls the dtor for them.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20200517105051.9352-1-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 18bfbee..1d1d253 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1438,7 +1438,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 * appear not as the counts should be low
 		 */
 		if (unlikely(PageTransHuge(page)))
-			(*get_compound_page_dtor(page))(page);
+			destroy_compound_page(page);
 		else
 			list_add(&page->lru, &free_pages);
 		continue;
@@ -1859,7 +1859,7 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 
 			if (unlikely(PageCompound(page))) {
 				spin_unlock_irq(&pgdat->lru_lock);
-				(*get_compound_page_dtor(page))(page);
+				destroy_compound_page(page);
 				spin_lock_irq(&pgdat->lru_lock);
 			} else
 				list_add(&page->lru, &pages_to_free);