/usr/src/linux-headers-3.13.0-46-lowlatency/mm is in linux-headers-3.13.0-46-lowlatency 3.13.0-46.79.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/src/linux-headers-3.13.0-46-lowlatency/../linux-headers-3.13.0-46/mm