[lxc-devel] Error "unshare: Operation not permitted" when trying to create user container

[Brian Campbell]

On Feb 20, 2014, at 9:21 AM, Serge Hallyn <serge.hallyn at ubuntu.com> wrote:

> Quoting Brian Campbell (lambda at continuation.org):
>> On Feb 18, 2014, at 10:25 AM, Serge Hallyn <serge.hallyn at ubuntu.com> wrote:
>>> It looks like you're in the root cgroup and starting as non-root.
>>> Without being root you indeed do not have the rights to create new
>>> cgroups there.  You'll need to either use lxc as root, or do something
>>> like
>>> 
>>> for d in /sys/fs/cgroup/*; do
>>> 	sudo mkdir $d/lambda
>>> 	sudo chown -R lambda: $d/lambda
>>> 	echo $$ > $d/lambda/tasks
>>> done
>> 
>> 
>> Apologies for the slow followup, been a busy few days.
>> 
>> Doing that gives me an error on the the cpuset cgroup (added an echo to see which one it was):
>> 
>> /sys/fs/cgroup/blkio/lambda
>> /sys/fs/cgroup/cpu/lambda
>> /sys/fs/cgroup/cpuacct/lambda
>> /sys/fs/cgroup/cpu,cpuacct/lambda
>> /sys/fs/cgroup/cpuset/lambda
>> -bash: echo: write error: No space left on device
>> /sys/fs/cgroup/devices/lambda
>> /sys/fs/cgroup/freezer/lambda
>> /sys/fs/cgroup/net_cls/lambda
>> /sys/fs/cgroup/perf_event/lambda
>> /sys/fs/cgroup/systemd/lambda
>> 
>> I decided to see if it would work anyhow, but it still fails. Any clue why cpuset would be failing?
> 
> You need to either echo 1 > /sys/fs/cgroup/cpuset/cgroup.clone_children,
> or else manually cp cpuset.cpus and cpuset.mems from the parent to the
> child cgroup.  Otherwise you cannot place a task into the cgroup.

Yep, as I mentioned in my followup I figured that out (the manual part, I hadn't noticed clone_children), and got a bit further, but it's still failing:

     lxc-start 1392878417.586 INFO     lxc_start_ui - using rcfile /home/lambda/.local/share/lxc/precise-test/config
     lxc-start 1392878417.586 INFO     lxc_confile - read uid map: type u nsid 0 hostid 100000 range 65536
     lxc-start 1392878417.586 INFO     lxc_confile - read uid map: type g nsid 0 hostid 100000 range 65536
     lxc-start 1392878417.586 WARN     lxc_log - lxc_log_init called with log already initialized
     lxc-start 1392878417.586 INFO     lxc_lsm - LSM security driver nop
     lxc-start 1392878417.586 DEBUG    lxc_conf - allocated pty '/dev/pts/3' (5/6)
     lxc-start 1392878417.586 DEBUG    lxc_conf - allocated pty '/dev/pts/4' (7/8)
     lxc-start 1392878417.586 DEBUG    lxc_conf - allocated pty '/dev/pts/5' (9/10)
     lxc-start 1392878417.586 DEBUG    lxc_conf - allocated pty '/dev/pts/6' (11/12)
     lxc-start 1392878417.586 INFO     lxc_conf - tty's configured
     lxc-start 1392878417.587 DEBUG    lxc_start - sigchild handler set
     lxc-start 1392878417.587 DEBUG    lxc_console - opening /dev/tty for console peer
     lxc-start 1392878417.587 INFO     lxc_caps - Last supported cap was 34
     lxc-start 1392878417.587 DEBUG    lxc_console - using '/dev/tty' as console
     lxc-start 1392878417.587 DEBUG    lxc_console - 21308 got SIGWINCH fd 17
     lxc-start 1392878417.587 DEBUG    lxc_console - set winsz dstfd:14 cols:161 rows:55
     lxc-start 1392878417.847 INFO     lxc_start - 'precise-test' is initialized
     lxc-start 1392878417.875 DEBUG    lxc_start - Not dropping cap_sys_boot or watching utmp
     lxc-start 1392878417.875 INFO     lxc_start - Cloning a new user namespace
     lxc-start 1392878417.875 INFO     lxc_cgroup - cgroup driver cgroupfs initing for precise-test
     lxc-start 1392878417.876 ERROR    lxc_cgfs - Operation not permitted - Could not add pid 21330 to cgroup /lambda/precise-test: internal error
     lxc-start 1392878417.909 ERROR    lxc_start - failed to spawn 'precise-test'

After changing that error to provide a little more information, I found that the full path is:

lxc-start: Operation not permitted - Could not add pid 23235 to cgroup /sys/fs/cgroup/devices/lambda/precise-test/tasks

>> Also, what is handling creating these initial per-user cgroups on
>> Ubuntu? I'm just wondering where I can look to see it working
>> correctly to compare against my setup.
> 
> That's systemd-logind, in 14.04.  Before that you did have to do it by
> hand.

Ah, thanks.

-- Brian