** Changed in: linux (Ubuntu)
Status: Incomplete => Fix Released
** Changed in: linux (Ubuntu Focal)
Importance: Undecided => Medium
** Changed in: linux (Ubuntu Focal)
Status: Confirmed => In Progress
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https://bugs.launchpad.net/bugs/1988584
Title:
cgroup: all controllers mounted when using 'cgroup_no_v1='
Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Focal:
In Progress
Bug description:
[Impact]
When mounting a cgroup hierarchy with disabled controller in cgroup v1,
all available controllers will be attached.
For example, boot with cgroup_no_v1=cpu or cgroup_disable=cpu, and then
mount with "mount -t cgroup -ocpu cpu /sys/fs/cgroup/cpu", then all
enabled controllers will be attached except cpu.
This exists since linux v5.1 and fixed in linux v5.11 with this commit:
61e960b07b63 cgroup-v1: add disabled controller check in cgroup1_parse_param()
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=61e960b07b637
[Test Case]
root@dut-vm:~# kexec -l /boot/vmlinuz-5.4.0-122-generic
--initrd=/boot/initrd.img-5.4.0-122-generic --command-line="$(cat
/proc/cmdline) cgroup_no_v1=net_prio,net_cls"
root@dut-vm:~# systemctl kexec
root@dut-vm:~# mount | grep cgroup
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup2 on /sys/fs/cgroup/unified type cgroup2
(rw,nosuid,nodev,noexec,relatime,nsdelegate)
cgroup on /sys/fs/cgroup/systemd type cgroup
(rw,nosuid,nodev,noexec,relatime,xattr,name=systemd)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup
(rw,nosuid,nodev,noexec,relatime,cpuset,cpu,cpuacct,blkio,memory,devices,freezer,perf_event,hugetlb,pids,rdma)
=> All controllers are associated to /sys/fs/cgroup/net_cls,net_prio.
Note that several reboots may be needed to reproduce the problem (it fails
only when systemd tries to mount 'net_cls,net_prio' first, but the order is
random).
[Regression Potential]
The patch is located in cgroup1_parse_param(), the potential
regressions are low.
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