J'ai enlevé les headers kernel qui prenaient 25% de l'espace pour aucune utilité. On a de quoi respirer pour quelque mois 
root@mediawiki-smaller:/usr/src# ls | grep -v 4.4.0-103 | xargs dpkg --remove
Removing linux-headers-4.4.0-66-generic (4.4.0-66.87) ...
Removing linux-headers-4.4.0-70-generic (4.4.0-70.91) ...
Removing linux-headers-4.4.0-71-generic (4.4.0-71.92) ...
Removing linux-headers-4.4.0-72-generic (4.4.0-72.93) ...
Removing linux-headers-4.4.0-75-generic (4.4.0-75.96) ...
Removing linux-headers-4.4.0-78-generic (4.4.0-78.99) ...
Removing linux-headers-4.4.0-79-generic (4.4.0-79.100) ...
Removing linux-headers-4.4.0-81-generic (4.4.0-81.104) ...
Removing linux-headers-4.4.0-83-generic (4.4.0-83.106) ...
Removing linux-headers-4.4.0-87-generic (4.4.0-87.110) ...
Removing linux-headers-4.4.0-89-generic (4.4.0-89.112) ...
Removing linux-headers-4.4.0-92-generic (4.4.0-92.115) ...
Removing linux-headers-4.4.0-93-generic (4.4.0-93.116) ...
Removing linux-headers-4.4.0-96-generic (4.4.0-96.119) ...
Removing linux-headers-4.4.0-97-generic (4.4.0-97.120) ...
Removing linux-headers-4.4.0-98-generic (4.4.0-98.121) ...
Removing linux-headers-4.4.0-101 (4.4.0-101.124) ...
Removing linux-headers-4.4.0-66 (4.4.0-66.87) ...
Removing linux-headers-4.4.0-70 (4.4.0-70.91) ...
Removing linux-headers-4.4.0-71 (4.4.0-71.92) ...
Removing linux-headers-4.4.0-72 (4.4.0-72.93) ...
Removing linux-headers-4.4.0-75 (4.4.0-75.96) ...
Removing linux-headers-4.4.0-78 (4.4.0-78.99) ...
Removing linux-headers-4.4.0-79 (4.4.0-79.100) ...
Removing linux-headers-4.4.0-81 (4.4.0-81.104) ...
Removing linux-headers-4.4.0-83 (4.4.0-83.106) ...
Removing linux-headers-4.4.0-87 (4.4.0-87.110) ...
Removing linux-headers-4.4.0-89 (4.4.0-89.112) ...
Removing linux-headers-4.4.0-92 (4.4.0-92.115) ...
Removing linux-headers-4.4.0-93 (4.4.0-93.116) ...
Removing linux-headers-4.4.0-96 (4.4.0-96.119) ...
Removing linux-headers-4.4.0-97 (4.4.0-97.120) ...
Removing linux-headers-4.4.0-98 (4.4.0-98.121) ...