Hello. On Tue, Jun 25, 2024 at 11:12:20AM GMT, chenridong <chenridong@xxxxxxxxxx> wrote: > I am considering whether the cgroup framework has a method to fix this > issue, as other subsystems may also have the same underlying problem. > Since the root css will not be released, but the css->cgrp will be > released. <del>First part is already done in d23b5c5777158 ("cgroup: Make operations on the cgroup root_list RCU safe") second part is that</del> you need to take RCU read lock and check for NULL, similar to 9067d90006df0 ("cgroup: Eliminate the need for cgroup_mutex in proc_cgroup_show()") Does that make sense to you? A Fixes: tag would be nice, it seems at least a79a908fd2b08 ("cgroup: introduce cgroup namespaces") played some role. (Here the RCU lock is not for cgroup_roots list but to preserve the root cgrp itself css_free_rwork_fn/cgroup_destroy_root. HTH, Michal
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