Containers fail to start after updating to 1.1.1

[LenzGr]

After updating to lxc 1.1.1 on my Ubuntu 14.04.2 LTS system, my existing containers (created with 1.0.x) fail to start:

% sudo lxc-start -d -n centos6base
lxc-start: lxc_start.c: main: 344 The container failed to start.
lxc-start: lxc_start.c: main: 346 To get more details, run the container in foreground mode.
lxc-start: lxc_start.c: main: 348 Additional information can be obtained by setting the --logfile and --logpriority options.

Writing the errors to a log file reveals the following:

lxc-start 1426789048.197 ERROR    lxc_apparmor - lsm/apparmor.c:apparmor_process_label_set:169 - If you really want to start this container, set
lxc-start 1426789048.197 ERROR    lxc_apparmor - lsm/apparmor.c:apparmor_process_label_set:170 - lxc.aa_allow_incomplete = 1
lxc-start 1426789048.197 ERROR    lxc_apparmor - lsm/apparmor.c:apparmor_process_label_set:171 - in your container configuration file
lxc-start 1426789048.197 ERROR    lxc_sync - sync.c:__sync_wait:51 - invalid sequence number 1. expected 4
lxc-start 1426789048.197 ERROR    lxc_start - start.c:__lxc_start:1157 - failed to spawn 'centos6base'
lxc-start 1426789048.197 ERROR    lxc_cgmanager - cgmanager.c:cgm_remove_cgroup:518 - call to cgmanager_remove_sync failed: invalid request
lxc-start 1426789048.197 ERROR    lxc_cgmanager - cgmanager.c:cgm_remove_cgroup:520 - Error removing all:lxc/centos6base-2
lxc-start 1426789053.235 ERROR    lxc_start_ui - lxc_start.c:main:344 - The container failed to start.
lxc-start 1426789053.235 ERROR    lxc_start_ui - lxc_start.c:main:346 - To get more details, run the container in foreground mode.
lxc-start 1426789053.235 ERROR    lxc_start_ui - lxc_start.c:main:348 - Additional information can be obtained by setting the --logfile and --logpriority options.

An upgrade should not break a previously working setup. I could not find any hint in the release notes about what steps I need to perform when updating to 1.1 in order to work around this problem.

[LenzGr]

This only occurred when running the mainline kernel I installed for testing a different LXC issue I reported a while ago (vmlinuz-3.19.0-031900rc6-generic). Using the stock kernel shipped with 14.04.2 (vmlinuz-3.13.0-46-generic) did not show this behaviour - the container started as expected. Sorry for the noise!