Hi Michal,

On 2021/1/14 21:12, Michal Koutný wrote:

Hello Chen.

On Fri, Dec 18, 2020 at 02:17:55PM +0800, Chen Zhou [off-list ref] wrote:

quoted

When mounting a cgroup hierarchy with disabled controller in cgroup v1,
all available controllers will be attached.

Not sure if I understand the situation -- have you observed a v1
controller attached to a hierarchy while specifying cgroup_no_v1= kernel
cmdline arg?

Yeah, this is the situation.
In this case, at the beginning of function check_cgroupfs_options(), the mask
ctx->subsys_mask will be 0. And if we mount without 'none' and 'name=' options,
then in check_cgroupfs_options(), the flag ctx->all_ss will be set, that is, select all the subsystems.

Thanks,
Chen Zhou

AFAICS, the disabled controllers are honored thanks to
check_cgroupfs_options().

Michal