Re: [PATCH v3 net-next 12/12] net-memcg: Decouple controlled memcg from global protocol memory accounting.

[Martin KaFai Lau <martin.lau@linux.dev>]

On 8/13/25 1:53 PM, Shakeel Butt wrote:
> What I think is the right approach is to have BPF struct ops based
> approach with possible callback 'is this socket under pressure' or maybe
> 'is this socket isolated' and then you can do whatever you want in those
> callbacks. In this way your can follow the same approach of caching the
> result in kernel (lower bits of sk->sk_memcg).
> 
> I am CCing bpf list to get some suggestions or concerns on this
> approach.

I have quickly looked at the set. In patch 11, it sets a bit in sk->sk_memcg.

On the bpf side, there are already cgroup bpf progs that can do bpf_setsockopt 
on a sk, so the same can be done here. The bpf_setsockopt does not have to set 
option/knob that is only available in the uapi in case we don't want to expose 
this to the user space.

The cgroup bpf prog (BPF_CGROUP_INET_SOCK_CREATE) can already be run when a 
"inet" sock is created. This hook (i.e. attach_type) does not have access to 
bpf_setsockopt but should be easy to add.

For more comprehensive mem charge policy that needs new bpf hook, that probably 
will need struct_ops instead of another cgroup attach_type but that will be 
implementation details.