[Devel] Re: cgroup tasks file error

[Serge Hallyn]

Quoting ccmail111 (ccmail111 at yahoo.com):
> 
> Isn't ns mounted by default ?

I thought that in an earlier email you said you had done

	mount -t cgroup cpuset -ocpuset /dev/cgroup

in which case ns would not be mounted.  But note, we DO NOT
want you to have ns mounted :)

> I rebooted machine,
> based on 2.6.32 kernel.
> 
> Then,
> 
> [host:~]$ mkdir /dev/cgroup
> [host:~]$ mount -t cgroup cpuset -ocpuset,ns /dev/cgroup
> [host:~]$ ps aux | grep libvirt
> root       575  0.6  0.9  88816  2216 ?        Sl   17:28   0:00 myproc --daemon
> root       654  0.0  0.2   4044   664 ttyS0    S+   17:29   0:00 grep libvirt
> [host:~]$ mkdir /dev/cgroup/hello
> [host:~]$ cat /dev/cgroup/hello/tasks
> [host:~]$ echo 0 > /dev/cgroup/hello/cpuset.cpus
> [host:~]$ echo 0 > /dev/cgroup/hello/cpuset.mems
> [host:~]$ echo 575 > /dev/cgroup/hello/tasks
> [host:~]$ cat /dev/cgroup/hello/tasks
> 575
> [host:~]$ id
> uid=0(root) gid=0(root) groups=0(root)
> [host:~]$
> 
> Now, I try to move the task out - the parent/root:
> 
> [host:~]$ echo 575 > /dev/cgroup/tasks
> -bash: echo: write error: Operation not permitted
> 
> 
> Any thoughts !?

Yes, ns cgroup is forbidding you from moving back :)  Mount without it.

-serge
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