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Commit c731ae1d authored by Li Zefan's avatar Li Zefan Committed by Tejun Heo
Browse files

cgroup: disallow disabled controllers on the default hierarchy 



After booting with cgroup_disable=memory, I still saw memcg files
in the default hierarchy, and I can write to them, though it won't
take effect.

  # dmesg
  ...
  Disabling memory control group subsystem
  ...
  # mount -t cgroup -o __DEVEL__sane_behavior xxx /cgroup
  # ls /cgroup
  ...
  memory.failcnt                   memory.move_charge_at_immigrate
  memory.force_empty               memory.numa_stat
  memory.limit_in_bytes            memory.oom_control
  ...
  # cat /cgroup/memory.usage_in_bytes
  0

tj: Minor comment update.

Signed-off-by: default avatarLi Zefan <lizefan@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 1f779fb2

kernel/cgroup.c

+9 −5
Original line number Diff line number Diff line
@@ -3069,6 +3069,9 @@ int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) 
{

	int ret;



	if (ss->disabled)

		return 0;



	if (!cfts || cfts[0].name[0] == '\0')

		return 0;
@@ -4678,8 +4681,6 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) 


	BUG_ON(online_css(css));



	cgrp_dfl_root.subsys_mask |= 1 << ss->id;



	mutex_unlock(&cgroup_mutex);

}
@@ -4758,12 +4759,15 @@ int __init cgroup_init(void) 
			      &cgrp_dfl_root.cgrp.e_csets[ssid]);



		/*

		 * cftype registration needs kmalloc and can't be done

		 * during early_init.  Register base cftypes separately.

		 * Setting dfl_root subsys_mask needs to consider the

		 * disabled flag and cftype registration needs kmalloc,

		 * both of which aren't available during early_init.

		 */

		if (ss->base_cftypes)

		if (!ss->disabled) {

			cgrp_dfl_root.subsys_mask |= 1 << ss->id;

			WARN_ON(cgroup_add_cftypes(ss, ss->base_cftypes));

		}

	}



	cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);

	if (!cgroup_kobj)