mm/migration: remove unneeded lock page and PageMovable check

When non-lru movable page was freed from under us, __ClearPageMovable must
have been done.  So we can remove unneeded lock page and PageMovable check
here.  Also free_pages_prepare() will clear PG_isolated for us, so we can
further remove ClearPageIsolated as suggested by David.

Link: https://lkml.kernel.org/r/20220530113016.16663-3-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/migrate.c

@@ -1090,15 +1090,10 @@ static int unmap_and_move(new_page_t get_new_page,
 		return -ENOSYS;
 
 	if (page_count(page) == 1) {
-		/* page was freed from under us. So we are done. */
+		/* Page was freed from under us. So we are done. */
 		ClearPageActive(page);
 		ClearPageUnevictable(page);
-		if (unlikely(__PageMovable(page))) {
-			lock_page(page);
-			if (!PageMovable(page))
-				ClearPageIsolated(page);
-			unlock_page(page);
-		}
+		/* free_pages_prepare() will clear PG_isolated. */
 		goto out;
 	}