/usr/src/linux-headers-4.4.0-112-generic/mm is in linux-headers-4.4.0-112-generic 4.4.0-112.135.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/src/linux-headers-4.4.0-112-generic/../linux-headers-4.4.0-112/mm