[Lxc-users] cgroup question

[Serge Hallyn]

Quoting Kevin Wilson (wkevils at gmail.com):
> Hello,
> Thanks a lot for your answer.
> 
> I reproduced the problem:
> this is what I run: (after boot, in  Ubuntu 12.10)
> 
> mount -t tmpfs    cgroup_root    /cgroup
> 
> mkdir /cgroup/test1
> mount -t cgroup -o cpuset,devices mytest    /cgroup/test1
> 
> And I get:
> mount: mytest already mounted or /cgroup/test1 busy
> 
> shouldn't it work ?
> 
> I tried it on Ubuntu.
> I was surprised to see that some cgroup contolkers are  mounted
> under /sys/fs/cgroup (though it seems to me that this should not cause
> a problem).

It wouldn't cause a problem if you were mounting them separately,
but you are asking for controllers to be bound together, which have
already been separately mounted.  That is not possible.

So for instance

mkdir /tmp/1 /tmp/2 /tmp/3
mount -t cgroup -o freezer /tmp/1
mount -t cgroup -o freezer /tmp/2
mount -t cgroup -o freezer /tmp/3

is ok, but

mkdir /tmp/1 /tmp/2 /tmp/3
mount -t cgroup -o freezer /tmp/1
mount -t cgroup -o cpuset /tmp/2
mount -t cgroup -o cpuset,freezer /tmp/3

is not

> systemd is not running on Ubuntu, I don't have any idea
> who
> mounted in boot time the /sys/fs/cgroup contollers and for which purpose
> 
> mount | grep cgroup
> gives:
> 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_root on /cgroup type tmpfs (rw)

look for a cgroup related package, or lines in your fstab:

dpkg -l | grep cgroup
grep cgroup /etc/fstab

-serge