Re: [tor-dev] tor#16518: Read-Only Filesystem Error opening tor lockfile in 0.2.6.9 but not 0.2.5.12

Sounds like access control gone wrong. An older version works but a newer version fails. Permissions on the filesystem look fine from mount output. So do you use access control, apparmor, selinux, grsecurity, fsprotect, bilibop, etc? In particular the tor package which is mentioned in your ticket includes an apparmor profile and suggests apparmor-utils.

Also try checking your system logs --leeroy