Cgroup change results in "No space left on device" or "Error Code: 5001"

Issue

• Reclassifying a task produces the following output

  r6 # echo 2035 > /cgroup/cpuset/test/tasks 
  -bash: echo: write error: No space left on device
  

• Many errors are seen when starting cgroups:

  Oct 12 11:28:18 hostname CGRE[4809]: Started the CGroup Rules Engine Daemon.
  Oct 12 11:28:18 hostname CGRE[4809]: Cgroup change for PID: 4810, UID: 0, GID: 0, PROCNAME: /bin/touch FAILED! (Error Code: 50016)
  Oct 12 11:28:21 hostname CGRE[4809]: Cgroup change for PID: 4812, UID: 0, GID: 0, PROCNAME: /usr/bin/strace FAILED! (Error Code: 50016)
  Oct 12 11:28:21 hostname CGRE[4809]: Cgroup change for PID: 4813, UID: 0, GID: 498, PROCNAME: /bin/cgexec FAILED! (Error Code: 50016)
  Oct 12 11:28:21 hostname CGRE[4809]: Cgroup change for PID: 4813, UID: 0, GID: 498, PROCNAME: /bin/cgexec FAILED! (Error Code: 50016)
  Oct 12 11:28:21 hostname CGRE[4809]: Cgroup change for PID: 4813, UID: 0, GID: 0, PROCNAME: /bin/cgexec FAILED! (Error Code: 50016)
  Oct 12 11:29:08 hostname CGRE[4809]: Cgroup change for PID: 4814, UID: 0, GID: 0, PROCNAME: /bin/ls FAILED! (Error Code: 50016)
  

• Running strace against cgexec shows:

  # strace -f cgexec -g cpuset:app /bin/bash
  execve("/bin/cgexec", ["cgexec", "-g", "cpuset:app", "/bin/bash"], [/* 47 vars */]) = 0
  .
  .
  . <snip>
  .
  .open("/cgroup/cpuset/app//tasks", O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0666) = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f0e169fc000
  write(3, "4813", 4)                     = -1 ENOSPC (No space left on device)
  close(3)                                = 0
  munmap(0x7f0e169fc000, 4096)            = 0
  write(2, "cgroup change of group failed\n", 30cgroup change of group failed
  ) = 30
  exit_group(50016)