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: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3f46165..3edcc8a 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3069,6 +3069,9 @@
{
int ret;
+ if (ss->disabled)
+ return 0;
+
if (!cfts || cfts[0].name[0] == '\0')
return 0;
@@ -4678,8 +4681,6 @@
BUG_ON(online_css(css));
- cgrp_dfl_root.subsys_mask |= 1 << ss->id;
-
mutex_unlock(&cgroup_mutex);
}
@@ -4758,11 +4759,14 @@
&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);
