mm/memory_hotplug: fix misplaced comment in offline_pages

It's misplaced since commit 7960509 ("mm, memory_hotplug: print
reason for the offlining failure").  Move it to the right place.

Link: https://lkml.kernel.org/r/20220207133643.23427-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

Author: MiaoheLin

mm/memory_hotplug.c

@@ -1963,6 +1963,7 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages,
 	return 0;
 
 failed_removal_isolated:
+	/* pushback to free area */
 	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 	memory_notify(MEM_CANCEL_OFFLINE, &arg);
 failed_removal_pcplists_disabled:
@@ -1973,7 +1974,6 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages,
 		 (unsigned long long) start_pfn << PAGE_SHIFT,
 		 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1,
 		 reason);
-	/* pushback to free area */
 	mem_hotplug_done();
 	return ret;
 }