Hello, Zhang.
On Mon, Dec 14, 2015 at 07:45:54PM +0800, kyler.zhangkui@xxxxxxxxxx wrote:
> @@ -2147,6 +2147,13 @@ static void cgroup_kill_sb(struct super_block *sb)
> {
> struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
> struct cgroup_root *root = cgroup_root_from_kf(kf_root);
> + struct cgroup *child;
> + int live_child = 0;
> +
> + mutex_lock(&cgroup_mutex);
> + cgroup_for_each_live_child(child, &root->cgrp) {
> + live_child++;
> + }
>
> /*
> * If @root doesn't have any mounts or children, start killing it.
> @@ -2155,12 +2162,12 @@ static void cgroup_kill_sb(struct super_block *sb)
> *
> * And don't kill the default root.
> */
> - if (!list_empty(&root->cgrp.self.children) ||
> - root == &cgrp_dfl_root)
> - cgroup_put(&root->cgrp);
> + if (live_child || root == &cgrp_dfl_root)
> + cgroup_put(&root->cgrp);
> else
> percpu_ref_kill(&root->cgrp.self.refcnt);
>
> + mutex_unlock(&cgroup_mutex);
> kernfs_kill_sb(sb);
I don't know. With the above change, we might fail remounting with
the same option for some controllers which keep residual objects
around. Changing controller associations has never been supported
correctly and I don't think it'll ever be. I have no objection to
improving it but this has the potential to regress use cases which
would be more common.
Thanks.
--
tejun
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