Re: [PATCH v2] cgroup: memcg: net: do not associate sock with unrelated cgroup

[Shakeel Butt]

On Fri, Feb 14, 2020 at 3:12 PM Eric Dumazet <edumazet@xxxxxxxxxx> wrote:
>
> On Fri, Feb 14, 2020 at 2:48 PM Shakeel Butt <shakeelb@xxxxxxxxxx> wrote:
>
> >
> > I think in the current code if the association is skipped at
> > allocation time then the sock will remain unassociated for its
> > lifetime.
> >
> > Maybe we can add the association in the later stages but it seems like
> > it is not a simple task i.e. edbe69ef2c90f ("Revert "defer call to
> > mem_cgroup_sk_alloc()"").
>
> Half TCP sockets are passive, so this means that 50% of TCP sockets
> won't be charged.
> (the socket cloning always happens from BH context)
>
> I think this deserves a comment in the changelog or documentation,
> otherwise some people might think
> using memcg will make them safe.

Thanks I will update the changelog. Also is inet_csk_accept() the
right place for delayed cgroup/memcg binding (if we decide to do
that). I am wondering if we can force charge the memcg during late
binding to cater the issue fixed in edbe69ef2c90f.

Shakeel