Comment 0 for bug 1730926

This is a POTENTIAL REGRESSION.

This test has passed with older kernels (4.4.0-98, 4.4.0-97, 4.4.0-96), but this time it failed.
Issue can be seen on zKVM, zVM and Ubuntu on LPAR

Steps:
1. Install lxc-tests
2. Run sudo /usr/bin/lxc-test-unpriv

Result:
  ---
  mount: wrong fs type, bad option, bad superblock on none,
         missing codepage or helper program, or other error

         In some cases useful info is found in syslog - try
         dmesg | tail or so.
  umount: /tmp/tmp.uMnoGYXJSH/ovl_symlink_test/overlayfs: not mounted
  /usr/sbin/deluser: The user `lxcunpriv' does not exist.
  Path existed
  Using image from local cache
  Unpacking the rootfs

  ---
  You just created an Ubuntu container (release=xenial, arch=s390x, variant=default)

  To enable sshd, run: apt-get install openssh-server

  For security reason, container images ship without user accounts
  and without a root password.

  Use lxc-attach or chroot directly into the rootfs to set a root password
  or create user accounts.
  Name: c1
  State: RUNNING
  PID: 5846
  CPU use: 0.05 seconds
  BlkIO use: 0 bytes
  Memory use: 10.04 MiB
  KMem use: 0 bytes
  Link: vethV2EVRI
   TX bytes: 0 bytes
   RX bytes: 0 bytes
   Total bytes: 0 bytes
  Name: c1
  State: RUNNING
  PID: 6218
  CPU use: 0.03 seconds
  BlkIO use: 0 bytes
  Memory use: 1.50 MiB
  KMem use: 0 bytes
  Link: vethA54DMR
   TX bytes: 0 bytes
   RX bytes: 0 bytes
   Total bytes: 0 bytes
  Testing containers under different cgroups per subsystem
  call to cgmanager_move_pid_main_sync failed: invalid request
  c2 is not running
  c1 is not running
  Removing user `lxcunpriv' ...
  Warning: group `lxcunpriv' has no more members.
  Done.
  FAIL
  ---

The mount error (bug 1730915) is not the cause, it looks like the failure was caused by:
  call to cgmanager_move_pid_main_sync failed: invalid request

In that shell script, this line account for the error:
    cgm movepid freezer x1 $$

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-100-generic 4.4.0-100.123
ProcVersionSignature: Ubuntu 4.4.0-100.123-generic 4.4.95
Uname: Linux 4.4.0-100-generic s390x
NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
AlsaDevices: Error: command ['ls', '-l', '/dev/snd/'] failed with exit code 2: ls: cannot access '/dev/snd/': No such file or directory
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: s390x
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
Date: Wed Nov 8 04:39:12 2017
HibernationDevice: RESUME=UUID=ca468a9c-9563-442c-85c6-6055e800a66e
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
Lspci:

Lsusb: Error: command ['lsusb'] failed with exit code 1:
PciMultimedia:

ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C
 SHELL=/bin/bash
ProcFB: Error: [Errno 2] No such file or directory: '/proc/fb'
ProcKernelCmdLine: root=UUID=b65b756a-ba4e-4c53-aa32-0db2bdb50bb3 crashkernel=196M
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-100-generic N/A
 linux-backports-modules-4.4.0-100-generic N/A
 linux-firmware 1.157.13
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)