Can not remove the subdirectory in cgroup pseudo-filesystem

[anqin]

>
> Yes you have to initialize some cpuset files first.  Otherwise
> the tasks have no access to any memory or cpus.
>

Oh... thank you for reminding. Previously, I run my tests in
a experimental kernel, it seems someone has set the
parameters.


BTW, is it possible currently to combine two tasks into
one cgroup? for instance, I have run two bashes (bash_A and
bash_B). Now, in bash_A, I created a cgroup in procfs:

# mount -t cgroup cgroup /mnt/cgrp
# 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

It seems the cgroup can not couple two irrelevant
task together, right?


Best,

Anqin