title: getting 'cgroup change of group failed' when trying to add process to cgroup
body: <p>I did the following both on <strong>Ubuntu 14</strong> and <strong>SUSE Linux Enterprise Server 11 (x86_64)</strong> where libcgroup is installed, with root:</p>
  
  <blockquote>
    <p>cgcreate -t ngam:home -a ngam:home -g cpuset:/nadav2ndCpuSet</p>
    
    <p>cgset -r cpuset.cpus=1 nadav2ndCpuSet</p>
  </blockquote>
  
  <p>After that, if you cat <strong>/sys/fs/cgroup/cpuset/nadav2ndCpuSet/cpuset.cpus</strong>,
  you will get:
  1</p>
  
  <p>which is good! as it is supposed to work.</p>
  
  <p>Then, from user <strong>ngam</strong>, I ran the following cmd:</p>
  
  <blockquote>
    <p>cgexec -g cpuset:nadav2ndCpuSet ~/whileLoop</p>
  </blockquote>
  
  <p>where <strong>whileLoop</strong> is just a simple program that runs in a loop doing sqrt.</p>
  
  <p>After that, I got the following error msg:</p>
  
  <p><strong>cgroup change of group failed</strong></p>
  
  <p>Why is it happening? 
  Thanks!</p>