memcg_stat from controllers test suite in LTP failed (hierarchical_memory_limit is 4096, 8192 expected)

 memcg_stat_test 1 TINFO: Starting test 1
 sh: echo: I/O error
 memcg_stat_test 1 TINFO: set /dev/memcg/memory.use_hierarchy to 0 failed
 memcg_stat_test 1 TINFO: Running memcg_process --shm -k 3 -s 135168
 memcg_stat_test 1 TINFO: Warming up pid: 31352
 memcg_stat_test 1 TINFO: Process is still here after warm up: 31352
 memcg_stat_test 1 TPASS: cache is 135168 as expected
 memcg_stat_test 2 TINFO: Starting test 2
 sh: echo: I/O error
 memcg_stat_test 2 TINFO: set /dev/memcg/memory.use_hierarchy to 0 failed
 memcg_stat_test 2 TINFO: Running memcg_process --mmap-file -s 135168
 memcg_stat_test 2 TINFO: Warming up pid: 31380
 memcg_stat_test 2 TINFO: Process is still here after warm up: 31380
 memcg_stat_test 2 TPASS: mapped_file is 135168 as expected
 memcg_stat_test 3 TINFO: Starting test 3
 sh: echo: I/O error
 memcg_stat_test 3 TINFO: set /dev/memcg/memory.use_hierarchy to 0 failed
 memcg_stat_test 3 TINFO: Running memcg_process --mmap-lock1 -s 4096
 memcg_stat_test 3 TINFO: Warming up pid: 31409
 memcg_stat_test 3 TINFO: Process is still here after warm up: 31409
 memcg_stat_test 3 TPASS: unevictable is 4096 as expected
 memcg_stat_test 4 TINFO: Starting test 4
 sh: echo: I/O error
 memcg_stat_test 4 TINFO: set /dev/memcg/memory.use_hierarchy to 0 failed
 memcg_stat_test 4 TINFO: Running memcg_process --mmap-lock2 -s 4096
 memcg_stat_test 4 TINFO: Warming up pid: 31434
 memcg_stat_test 4 TINFO: Process is still here after warm up: 31434
 memcg_stat_test 4 TPASS: unevictable is 4096 as expected
 memcg_stat_test 5 TINFO: Starting test 5
 sh: echo: I/O error
 memcg_stat_test 5 TINFO: set /dev/memcg/memory.use_hierarchy to 0 failed
 memcg_stat_test 5 TPASS: hierarchical_memory_limit is 4096 as expected
 memcg_stat_test 6 TINFO: Starting test 6
 sh: echo: I/O error
 memcg_stat_test 6 TINFO: set /dev/memcg/memory.use_hierarchy to 0 failed
 sh: echo: I/O error
 memcg_stat_test 6 TFAIL: hierarchical_memory_limit is 4096, 8192 expected
 memcg_stat_test 7 TINFO: Starting test 7
 sh: echo: I/O error
 memcg_stat_test 7 TINFO: set /dev/memcg/memory.use_hierarchy to 0 failed
 memcg_stat_test 7 TCONF: mem+swap is not enabled
 memcg_stat_test 7 TINFO: Starting test 8
 sh: echo: I/O error
 memcg_stat_test 7 TINFO: set /dev/memcg/memory.use_hierarchy to 0 failed
 memcg_stat_test 7 TCONF: mem+swap is not enabled
 tag=memcg_stat stime=1558504742 dur=4 exit=exited stat=33 core=no cu=16 cs=10

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-50-generic 4.15.0-50.54
ProcVersionSignature: User Name 4.15.0-50.54-generic 4.15.18
Uname: Linux 4.15.0-50-generic x86_64
AlsaDevices:
 total 0
 crw-rw---- 1 root audio 116, 1 May 22 02:57 seq
 crw-rw---- 1 root audio 116, 33 May 22 02:57 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay': 'aplay'
ApportVersion: 2.20.9-0ubuntu7.6
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord': 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CurrentDmesg:
 [14538.862950] cfg80211: Loading compiled-in X.509 certificates for regulatory database
 [14538.874559] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
Date: Wed May 22 07:17:43 2019
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig': 'iwconfig'
Lsusb: Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: QEMU Standard PC (i440FX + PIIX, 1996)
PciMultimedia:

ProcFB: 0 cirrusdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-50-generic root=UUID=576666e8-9e7f-40ee-934e-f1dce18323e5 ro
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-50-generic N/A
 linux-backports-modules-4.15.0-50-generic N/A
 linux-firmware 1.173.6
RfKill: Error: [Errno 2] No such file or directory: 'rfkill': 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/01/2014
dmi.bios.vendor: SeaBIOS
dmi.bios.version: Ubuntu-1.8.2-1ubuntu1
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: pc-i440fx-xenial
dmi.modalias: dmi:bvnSeaBIOS:bvrUbuntu-1.8.2-1ubuntu1:bd04/01/2014:svnQEMU:pnStandardPC(i440FX+PIIX,1996):pvrpc-i440fx-xenial:cvnQEMU:ct1:cvrpc-i440fx-xenial:
dmi.product.name: Standard PC (i440FX + PIIX, 1996)
dmi.product.version: pc-i440fx-xenial
dmi.sys.vendor: QEMU