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

[Roman Gushchin]

Tejun Heo <tj@xxxxxxxxxx> 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!