mm: export split_page()

This symbol will be used in the Hyper-V balloon driver to support 2M
allocations.
Signed-off-by: NK.  Y.  Srinivasan <kys@microsoft.com>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

mm/page_alloc.c

@@ -1397,6 +1397,7 @@ void split_page(struct page *page, unsigned int order)
 	for (i = 1; i < (1 << order); i++)
 		set_page_refcounted(page + i);
 }
+EXPORT_SYMBOL_GPL(split_page);
 
 static int __isolate_free_page(struct page *page, unsigned int order)
 {