The highperformance hooks can update the irqbalance configuration file to adjust the current banned cpu list,

depending on pod annotations. This is done to make sure that guaranteed pods that declare they don't want to have IRQ

processing on the CPUs they're assigned to, gets that.
When the update is done in-place, so likely most of the time,  a stray '\n' is added on every update. The single character

always adds up, creating a unbounded growth of the configuration file.
In practical terms, this is likely not really too bad, 
because we will need to get in the ballpark of thousands updates before the file size starts becoming concerning.


This bug is likely present since the first addition of the high performance hooks

$ crio --version
crio version 1.24.1-11.rhaos4.11.gitb0d2ef3.el8
Version:          1.24.1-11.rhaos4.11.gitb0d2ef3.el8
GoVersion:        go1.18.1
Compiler:         gc
Platform:         linux/amd64
Linkmode:         dynamic
BuildTags:        exclude_graphdriver_devicemapper, containers_image_ostree_stub, seccomp, selinux
SeccompEnabled:   true
AppArmorEnabled:  false
$ kubectl --version
Client Version: 4.10.9
Server Version: 4.11.0-0.nightly-2022-07-19-104004
Kubernetes Version: v1.24.0+9546431

Always

setup a cluster >= OCP 4.11 (for practical purposes, but the bug is likely here since the introduction of irq handling)
apply a performance profile like this minimal example[1], to get the runtimeclass deployed which enables the feature
create/delete pods like the example[2]
 

notice (oc debug node/...) after each pod creation a \n is added to /etc/sysconfig/irqbalance

obviously the file size can change (and grow) depending on the actual CPU ban list, but the rewrites should not cause unlimited '\n' to be added to the file

This has been fixed in 4.12 already, I am opening the bug to allow backports to earlier releases.

See: https://github.com/cri-o/cri-o/issues/6086
Patch: https://github.com/cri-o/cri-o/pull/6087