ubuntu_ltp_controllers:memcg_use_hirarchy: mkdir subgroup failed on s390x

[Stefan Bader]

On s390x nodes (zVM and LPAR) with hirsute:linux (5.11) on sru-20210927:

Running tests.......
memcg_use_hierarchy_test 1 TINFO: timeout per run is 0h 5m 0s
memcg_use_hierarchy_test 1 TINFO: set /dev/memcg/memory.use_hierarchy to 0 failed
memcg_use_hierarchy_test 1 TINFO: test if one of the ancestors goes over its limit, the proces will be killed
mkdir: cannot create directory ‘subgroup’: Cannot allocate memory
memcg_use_hierarchy_test 1 TBROK: mkdir subgroup failed
memcg_use_hierarchy_test 1 TINFO: AppArmor enabled, this may affect test results
memcg_use_hierarchy_test 1 TINFO: it can be disabled with TST_DISABLE_APPARMOR=1 (requires super/root)
memcg_use_hierarchy_test 1 TINFO: loaded AppArmor profiles: none

Summary:

passed 0
failed 0
broken 1
skipped 0
warnings 0

[Po-Hsu Lin (cypressyew)]

This issue can be found on OEM 5.14.0-1005.5 as well.
Note that this was tested on node onibi due to Intel lab outage.

[Po-Hsu Lin (cypressyew)]

This issue can be found on f-aws-5.13 5.13.0-1008.9~20.04.2 with instance c4.large only.