I have found the cause. It was running the cgm command from cgroup-lite package. But during the last SRU cycle, it got replaced by cgmanager package.
If you switch to the cgroup-lite, the SUT will pass with this test. ** Summary changed: - lxc-test-unpriv test failed on s390x instances + lxc-test-unpriv test failed on s390x instances with cgmanager ** Description changed: - Update: this can be reproduced with kernel downgraded to 4.4.0-98, see + Update2: Switching from cgroup-lite to cgmanager will trigger this + failure, see comment #4 + + Update1: this can be reproduced with kernel downgraded to 4.4.0-98, see comment #1 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) ** Also affects: cgmanager (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1730926 Title: lxc-test-unpriv test failed on s390x instances with cgmanager Status in cgmanager package in Ubuntu: New Status in linux package in Ubuntu: Confirmed Bug description: Update2: Switching from cgroup-lite to cgmanager will trigger this failure, see comment #4 Update1: this can be reproduced with kernel downgraded to 4.4.0-98, see comment #1 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) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/cgmanager/+bug/1730926/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp