Can not remove the subdirectory in cgroup pseudo-filesystem

anqin anqin.qin at
Thu Mar 26 20:06:36 PDT 2009

Thank you,

when I mount all cgroup subsystem to cgroupfs, it mounts also
the ns_cgroup which blocks the adding new taskes into given

If I mount a single subsystem (such as a memory), it can work.

>> # mount -t cgroup cgroup /mnt/cgrp
> mount cgroupfs with all cgroup subsystems is not so sane IMO.
>> # cd /mnt/cgrp
>> # mkdir test
>> # echo $$ > test/tasks
>> Then, I would like to add bash_B in this task group but
>> fail:
>> # echo #(PID_OF_bash_B) >  test/tasks
>> -bash: echo: write error: Operation not permitted
> That's because ns_cgroup is binded in this cgroup hierarchy, and
> it's ns_cgroup that prevents the task attaching, but a patch in
> -mm tree relaxes this check, and you won't see this restriction
> when using ns_cgroup.

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