[need-info] Does kubeadm require CONFIG_CGROUP_CPUACCT/DEVICE/FREEZER even with cgroups v2?

[Priyankasaggu11929]

Is it correct understanding that the following kernel config options (from the cgroups v1) are always need to be set/enabled by default on the node host, regardless of whether the node is configured to use cgroups v1 or v2?

CONFIG_CGROUP_CPUACCT: not set
CONFIG_CGROUP_DEVICE: not set
CONFIG_CGROUP_FREEZER: not set

If so, is this due to these kernel configs hardcoded in the following 2 places:

• system-validators/validators/types_unix.go

  Lines 46 to 48 in c8b796a

  	{Name: "CGROUP_CPUACCT"}, // cgroups v1 cpuacct
  	{Name: "CGROUP_DEVICE"},
  	{Name: "CGROUP_FREEZER"}, // cgroups v1 freezer

• system-validators/validators/types_unix.go

  Line 71 in c8b796a

  Cgroups: []string{"cpu", "cpuacct", "cpuset", "devices", "freezer", "memory", "pids"},

(For context, this is related to the OpenSUSE MicroOS community ticket – https://bugzilla.suse.com/show_bug.cgi?id=1249454)

Thank you so much, in advance for your help!

cc: @pacoxu

[neolit123]

that's a good question.

@pacoxu @KentaTada i think the kernel config is wrong.

related to cgroups* config options, there should be one list that works for both v1 and v2:

CGROUPS
CGROUP_PIDS
CGROUP_SCHED

and then if the user has v1 enabled we should check for these:

CGROUP_DEVICE
CGROUP_CPUACCT
CGROUP_FREEZER

if v2 is enabled we should check for:

CGROUP_BPF

does that mean we need a new fields in the spec called RequiredCgroupsV1, RequiredCgroupsV2 ?
i guess that also means running the cgroups v1 vs v2 check before the kernel config checks?

[neolit123]

i guess an alternative approach would be to just check for the shared kernel options

CGROUPS
CGROUP_PIDS
CGROUP_SCHED

and don't check for v1 / v2 specifics like

CGROUP_DEVICE
CGROUP_CPUACCT
CGROUP_FREEZER

and

CGROUP_BPF

we are checking the list of controllers anyhow

Cgroups: []string{"cpu", "cpuacct", "cpuset", "devices", "freezer", "memory", "pids"},

CgroupsV2: []string{"cpu", "cpuset", "devices", "freezer", "memory", "pids"},

which would imply that specific options are enabled.

also i'm confused why we don't have the bfp controller listed for v2, isn't it supposed to be there too?

[pacoxu]

/assign

This was introduced by #41.

[Priyankasaggu11929]

Thank you for the help, @neolit123 @pacoxu 🙏