CageFS can't start - Error: current running kernel is NOT supported

Issue

CageFS won't initialize due to an unsupported kernel:

# /usr/sbin/cagefsctl --init
Error: current running kernel is NOT supported 

Environment

• CloudLinux 7
• CloudLinux 8
• CageFS

Solution

1) Check the running kernel version - it should be CloudLinux kernel (CloudLinux kernel contains 'lve' in its name):

# uname -r
4.18.0-305.12.1.lve.el8.x86_64 

2) If the server is running with not CloudLinux kernel, but with CentOS or another OS kernel, then you need to switch the default kernel for boot (in Grub boot loader) to CloudLinux kernel and restart the server.

3) If the server is running with CloudLinux kernel, then you need to ensure that kmodlve module is installed and loaded:

# rpm -q kmod-lve
# lsmod | grep kmodlve

3) If kmod-lve package is not installed, please install (ensure that 'kmod' packages are not listed in yum.conf excludes):

# yum install kmod-lve

Then load the module manually:

# modprobe kmodlve

4) If kmod-lve is installed, but the module kmodlve is missing in lsmod list, try to load it manually:

# modprobe kmodlve
check:
# lsmod | grep kmodlve

5) If kmodlve could be loaded manually by modprobe but kmodlve is not loaded automatically during the reboot, then check the following:

a) if the kmodlve module isn't blacklisted in the modprobe configs

# grep lve /etc/modprobe.d/*
# grep black /etc/modprobe.d/*

b) check if 'systemd.unified_cgroup_hierarchy=1' parameter is present in the /etc/default/grub and remove it.

Then grub rebuild is required:

grub2-mkconfig -o /boot/grub2/grub.cfg

c) check if the modules are enabled in sysctl (should be set to '0'):

# sysctl -a|grep kernel.modules_disabled
kernel.modules_disabled = 0

d) check if liblve-devel liblve packages are not corrupted by using 'rpm -V'

e) check if lve services are not masked - try:

# modprobe kmodlve
# systemctl start lvectl
# systemctl start lve.service
# systemctl start lve_namespaces.service
# systemctl start lvestats.service

if the error about 'service is masked' then do:

# systemctl unmask lvectl.service
# systemctl unmask lve.service
# systemctl unmask lve_namespaces.service
# systemctl unmask lvestats.service

Cause

The lve module is not loaded.