Comment 2 for bug 1737005

The Ubuntu mainline kernel build unfortunately currently does not have apparmor set as the default LSM. This is due to some config changes done when adding the LSM stacking patches (Ubuntu tries to keep the configs as close as possible). Addressing this is wip and should land with the next revision of the LSM stacking patches

until then you can enable apparmor by editing the grub kernel command line by adding
  security=apparmor