[lxc-users] Problems with ns_cgroup; container fails to start

[phep]

Hi,

I cannot start LXC containers on my Debian testing (jessie) laptop anymore. 
This is how everything started:

   $ lxc-start -n test-lxc -f /var/lib/lxc/test-lxc/config
   lxc-start: no ns_cgroup option specified
   lxc-start: failed to spawn 'test-lxc'
   lxc-start: No such file or directory - failed to remove cgroup 
'/sys/fs/cgroup/cpuset//lxc/test-lxc'

These are the mounted cgroups, according to mount:

   $ mount | grep cgroup
   cgroup on /sys/fs/cgroup type tmpfs (rw,relatime,mode=755)
   cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,relatime,cpuset)
   cgroup on /sys/fs/cgroup/cpu type cgroup (rw,relatime,cpu)
   cgroup on /sys/fs/cgroup/cpuacct type cgroup (rw,relatime,cpuacct)
   cgroup on /sys/fs/cgroup/memory type cgroup (rw,relatime,memory)
   cgroup on /sys/fs/cgroup/devices type cgroup (rw,relatime,devices)
   cgroup_root on /sys/fs/cgroup type tmpfs (rw,relatime)
   cgroup on /sys/fs/cgroup/freezer type cgroup (rw,relatime,freezer)
   cgroup_memory on /sys/fs/cgroup/memory type cgroup 
(rw,nosuid,nodev,noexec,relatime,memory)
   cgroup_devices on /sys/fs/cgroup/devices type cgroup 
(rw,nosuid,nodev,noexec,relatime,devices)

and this is /proc/cgroups content:

   $ cat /proc/cgroups
   #subsys_name    hierarchy       num_cgroups     enabled
   cpuset  2       1       1
   cpu     3       1       1
   cpuacct 4       1       1
   memory  5       1       1
   devices 6       1       1
   freezer 7       1       1
   blkio   0       1       1
   perf_event      0       1       1

and, to be complete :
   $ tree /sys/fs/cgroup/
   /sys/fs/cgroup/
   |-- devices
   |   |-- cgroup.clone_children
   |   |-- cgroup.event_control
   |   |-- cgroup.procs
   |   |-- cgroup.sane_behavior
   |   |-- devices.allow
   |   |-- devices.deny
   |   |-- devices.list
   |   |-- notify_on_release
   |   |-- release_agent
   |   `-- tasks
   `-- memory
       |-- cgroup.clone_children
       |-- cgroup.event_control
       |-- cgroup.procs
       |-- cgroup.sane_behavior
       |-- memory.failcnt
       |-- memory.force_empty
       |-- memory.limit_in_bytes
       |-- memory.max_usage_in_bytes
       |-- memory.move_charge_at_immigrate
       |-- memory.oom_control
       |-- memory.pressure_level
       |-- memory.soft_limit_in_bytes
       |-- memory.stat
       |-- memory.swappiness
       |-- memory.usage_in_bytes
       |-- memory.use_hierarchy
       |-- notify_on_release
       |-- release_agent
       `-- tasks

As for the kernel cmdline :

   $ cat /proc/cmdline
   BOOT_IMAGE=/boot/vmlinuz-3.13-1-686-pae 
root=UUID=984f719f-8c9c-4686-8218-ee9657c96204 ro cgroup_enable=memory quiet

/etc/fstab does not contains cgroup stuff any more since it tented to 
conflict with libvirtd (I'm using KVM virtual machine at times). The 
cgroups, AFAICT, are created through libvirt-bin and cgroupfs-mount packages 
init.d scripts.

Trying to create the ns cgroup manually (after reading libvirtd-bin init.d 
script) fails also :

   $ mkdir /sys/fs/cgroup/ns
   $ mount -t cgroup -o rw,nosuid,nodev,noexec,relatime,ns "cgroup_ns" 
"/sys/fs/cgroup/ns"
   mount: special device cgroup_ns does not exist

I made some googling to no avail.

I wonder if this could come from some conflicts between cgroups handling 
from lxc vs. libvirt & Co...

Would anybody have any clue ?

Thanks in advance,

Patrice