I get:

/lib/modules/misc/cloop.o: unresolved symbol filp_open
/lib/modules/misc/cloop.o: unresolved symbol blk_cleanup_queue
/lib/modules/misc/cloop.o: unresolved symbol devfs_mk_dir
/lib/modules/misc/cloop.o: unresolved symbol end_that_request_last
/lib/modules/misc/cloop.o: unresolved symbol end_that_request_first
/lib/modules/misc/cloop.o: unresolved symbol filp_close
/lib/modules/misc/cloop.o: unresolved symbol do_generic_file_read
/lib/modules/misc/cloop.o: unresolved symbol blk_dev
/lib/modules/misc/cloop.o: unresolved symbol blk_init_queue
/lib/modules/misc/cloop.o: unresolved symbol mem_map
/lib/modules/misc/cloop.o: unresolved symbol devfs_register_blkdev

when I try to load the cloop module. The build process doesn't indicate anything wrong.
Any ideas?