/usr/lib/mpich-shmem/man/man4 is in mpich-shmem-bin 1.2.7-10ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/mpich-shmem/man/../../../share/man/man4
/usr/lib/mpich-shmem/man/../../../share/man/man4