APPLIED: [SRU][F][PATCH 0/1] fix all controllers mounted when using 'cgroup_no_v1='

[Stefan Bader]

On 08.09.22 23:18, Luke Nowakowski-Krijger wrote:
> These patches come from an SRU request by Nicolas Dichtel.
> 
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1988584
> 
> [Backport]
> 
> Replaced invalfc with invalf logging function as we don't want to
> backport the new changes to fs_context struct and the
> corresponding logging function changes.
> 
> The logging functions are functionally the same.
> 
> [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 at 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 at dut-vm:~# systemctl kexec
> root at 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.
> 
> Chen Zhou (1):
>    cgroup-v1: add disabled controller check in cgroup1_parse_param()
> 
>   kernel/cgroup/cgroup-v1.c | 3 +++
>   1 file changed, 3 insertions(+)
> 

Applied to focal:linux/master-next. Thanks.

-Stefan

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