'df -h' hangs on a machine without any network filesystems, why ?

Issue

• 'df -h' hangs on a machine without any network filesystems.

• Breaking the command using 'Ctrl+C' does not help.

# df
Filesystem                     Size  Used Avail Use% Mounted on
/dev/mapper/rootvg-rootlv      58G   16G   40G  28%  /
tmpfs                          7.8G  24K   7.8G 1%   /dev/shm
/dev/sda1                      194M   59M  125M  33% /boot