On Tue, Sep 2, 2025 at 11:55 AM Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote:
>
> On 8/28/25 6:00 PM, Kuniyuki Iwashima wrote:
> > mem_cgroup_sk_alloc() is called for SCTP before __inet_accept(),
> > so I added the protocol check in __inet_accept(), but this can be
> > removed once SCTP uses sk_clone_lock().
>
> > void __inet_accept(struct socket *sock, struct socket *newsock, struct sock *newsk)
> > {
> > + /* TODO: use sk_clone_lock() in SCTP and remove protocol checks */
> > + if (mem_cgroup_sockets_enabled &&
> > + (!IS_ENABLED(CONFIG_IP_SCTP) ||
> > + sk_is_tcp(newsk) || sk_is_mptcp(newsk))) {
>
> Instead of protocol check, is it the same as checking
> "if (mem_cgroup_sockets_enabled && !mem_cgroup_from_sk(newsk))"
sk_memcg could be NULL when the socket is belongs to the root
memcg, and then we shouldn't call kmem_cache_charge() for SCTP.
Also, SCTP's child sockets are not supported until we convert them to
sk_clone_lock(), and I plan to do so after this series lands on net-next.
https://github.com/q2ven/linux/commits/522_sctp_sk_clone_lock/
>
> > + gfp_t gfp = GFP_KERNEL | __GFP_NOFAIL;
> > +
> > + mem_cgroup_sk_alloc(newsk);
> > +
> > + if (mem_cgroup_from_sk(newsk)) {
> > + int amt;
> > +
> > + /* The socket has not been accepted yet, no need
> > + * to look at newsk->sk_wmem_queued.
> > + */
> > + amt = sk_mem_pages(newsk->sk_forward_alloc +
> > + atomic_read(&newsk->sk_rmem_alloc));
> > + if (amt)
> > + mem_cgroup_sk_charge(newsk, amt, gfp);
> > + }
> > +
> > + kmem_cache_charge(newsk, gfp);
> > + }
> > +
