mm/memory_hotplug: remove move_pfn_range()

Let's remove this indirection.  We need the zone in the caller either way,
so let's just detect it there.  Add some documentation for
move_pfn_range_to_zone() instead.

[akpm@linux-foundation.org: restore newline, per David]
Link: http://lkml.kernel.org/r/20190724142324.3686-1-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory_hotplug.c

@@ -714,8 +714,13 @@ static void __meminit resize_pgdat_range(struct pglist_data *pgdat, unsigned lon
 		pgdat->node_start_pfn = start_pfn;
 
 	pgdat->node_spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - pgdat->node_start_pfn;
-}
 
+}
+/*
+ * Associate the pfn range with the given zone, initializing the memmaps
+ * and resizing the pgdat/zone data to span the added pages. After this
+ * call, all affected pages are PG_reserved.
+ */
 void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
 		unsigned long nr_pages, struct vmem_altmap *altmap)
 {
@@ -804,20 +809,6 @@ struct zone * zone_for_pfn_range(int online_type, int nid, unsigned start_pfn,
 	return default_zone_for_pfn(nid, start_pfn, nr_pages);
 }
 
-/*
- * Associates the given pfn range with the given node and the zone appropriate
- * for the given online type.
- */
-static struct zone * __meminit move_pfn_range(int online_type, int nid,
-		unsigned long start_pfn, unsigned long nr_pages)
-{
-	struct zone *zone;
-
-	zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
-	move_pfn_range_to_zone(zone, start_pfn, nr_pages, NULL);
-	return zone;
-}
-
 int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
 {
 	unsigned long flags;
@@ -840,7 +831,8 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 	put_device(&mem->dev);
 
 	/* associate pfn range with the zone */
-	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
+	zone = zone_for_pfn_range(online_type, nid, pfn, nr_pages);
+	move_pfn_range_to_zone(zone, pfn, nr_pages, NULL);
 
 	arg.start_pfn = pfn;
 	arg.nr_pages = nr_pages;