Re: [PATCH v2 08/23] mm: introduce BPF kfuncs to deal with memcg pointers

Roman Gushchin
2025-10-28T18:12:46Z

Tejun Heo <tj@kernel.org> writes:

> On Mon, Oct 27, 2025 at 04:17:11PM -0700, Roman Gushchin wrote:
>> +__bpf_kfunc struct mem_cgroup *
>> +bpf_get_mem_cgroup(struct cgroup_subsys_state *css)
>> +{
>> + struct mem_cgroup *memcg = NULL;
>> + bool rcu_unlock = false;
>> +
>> + if (!root_mem_cgroup)
>> + return NULL;
>> +
>> + if (root_mem_cgroup->css.ss != css->ss) {
>> + struct cgroup *cgroup = css->cgroup;
>> + int ssid = root_mem_cgroup->css.ss->id;
>> +
>> + rcu_read_lock();
>> + rcu_unlock = true;
>> + css = rcu_dereference_raw(cgroup->subsys[ssid]);
>
> Would it make more sense to use cgroup_e_css()?

Good call, will update in the next version.

Thank you!