libcrun/cgroup: always enable TasksAccounting for systemd

[sohankunkerkar]

When using systemd cgroup driver with cgroup v2, unconditionally enable TasksAccounting. This ensures the pids controller is available even when no explicit pids resource limit is configured.

Without this, CRI-O cannot read pids.current from the cgroup, resulting in ProcessCount being reported as 0 for pod sandboxes. This causes Kubernetes Summary API conformance tests to fail.

The issue manifests specifically with pause/infra containers which typically do not have pids limits configured, leading to TasksAccounting not being enabled in the systemd scope properties.

This behavior matches what runc has been doing for a long time, where it unconditionally enables TasksAccounting for cgroup v2.

Fixes: cri-o/cri-o#9536

Summary by Sourcery

Unconditionally enable TasksAccounting in systemd cgroup v2 scopes to ensure the pids controller is available and fix ProcessCount reporting in CRI-O.

Bug Fixes:

• Always enable TasksAccounting in systemd cgroup scopes even when no pids limit is configured

Enhancements:

• Align libcrun behavior with runc by unconditionally enabling TasksAccounting for cgroup v2

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

In the systemd cgroup driver code for cgroup v2, TasksAccounting is now enabled unconditionally—removing the old guard and adding an explanatory comment—so that the pids controller is always active and CRI-O can correctly report pids.current as runc does.

File-Level Changes

Change	Details	Files
Unconditionally enable TasksAccounting for systemd cgroup scopes	Remove the 'if (resources->pids)' guard around TasksAccounting Add an unconditional boolean_opts entry for 'TasksAccounting' Insert comment explaining why TasksAccounting must always be enabled	src/libcrun/cgroup-systemd.c

Assessment against linked issues

Issue	Objective	Addressed	Explanation
cri-o/cri-o#9536	Ensure that ProcessCount in pod sandbox stats is correctly populated (>=1) when using crun as the OCI runtime with systemd cgroup v2, matching the behavior of runc.	✅
cri-o/cri-o#9536	Enable TasksAccounting unconditionally for systemd cgroup v2 in crun, so that the pids controller is available and pids.current can be read even when no explicit pids resource limit is configured.	✅

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[sourcery-ai]

Hey there - I've reviewed your changes and they look great!

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[flouthoc]

LGTM

[giuseppe]

LGTM