Re: [PATCH 1/2] cgroup: Fix incorrect warning from cgroup_apply_control_disable()
From: Tejun Heo <hidden>
Date: 2021-09-13 18:06:02
Also in:
lkml
Hello, On Thu, Sep 09, 2021 at 10:42:55PM -0400, Waiman Long wrote:
quoted hunk ↗ jump to hunk
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 881ce1470beb..e31bca9fcd46 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c@@ -3140,7 +3140,16 @@ static void cgroup_apply_control_disable(struct cgroup *cgrp) if (!css) continue; - WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt)); + /* + * A kill_css() might have been called previously, but + * the css may still linger for a while before being + * removed. Skip it in this case. + */ + if (percpu_ref_is_dying(&css->refcnt)) { + WARN_ON_ONCE(css->parent && + cgroup_ss_mask(dsct) & (1 << ss->id)); + continue; + }
This warning did help me catch some gnarly bugs. Any chance we can keep it for normal cases and elide it just for remounting? Thanks. -- tejun