Re: [PATCH v4 bpf-next/net 1/5] tcp: Save lock_sock() for memcg in inet_csk_accept().

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

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))"

> +		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);
> +	}
> +