/usr/src/linux-headers-4.15.0-1016-aws/mm is in linux-headers-4.15.0-1016-aws 4.15.0-1016.16.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/src/linux-headers-4.15.0-1016-aws/../linux-aws-headers-4.15.0-1016/mm