On Fri, Jan 26, 2024 at 09:19:25PM +0000, "T.J. Mercier" <tjmercier@xxxxxxxxxx> wrote:
> The root memcg is onlined even when memcg is disabled. When it's onlined
> a 2 second periodic stat flush is started, but no stat flushing is
> required when memcg is disabled because there can be no child memcgs.
> Most calls to flush memcg stats are avoided when memcg is disabled as a
> result of the mem_cgroup_disabled check added in 7d7ef0a4686a
> ("mm: memcg: restore subtree stats flushing"), but the periodic flushing
> started in mem_cgroup_css_online is not. Skip it.
Have you tried
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6099,6 +6099,9 @@ int __init cgroup_init(void)
cgroup_unlock();
for_each_subsys(ss, ssid) {
+ if (!cgroup_ssid_enabled(ssid))
+ continue;
+
if (ss->early_init) {
struct cgroup_subsys_state *css =
init_css_set.subsys[ss->id];
@@ -6118,9 +6121,6 @@ int __init cgroup_init(void)
* disabled flag and cftype registration needs kmalloc,
* both of which aren't available during early_init.
*/
- if (!cgroup_ssid_enabled(ssid))
- continue;
-
if (cgroup1_ssid_disabled(ssid))
pr_info("Disabling %s control group subsystem in v1 mounts\n",
ss->legacy_name);
?
I'm asking about a try because I'm not sure whether this does not blow
up due to something missing. But I think disabled controllers would not
need to be (root-)onlined at all.
Thanks,
Michal
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