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tcp: Save lock_sock() for memcg in inet_csk_accept().

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If memcg is enabled, accept() acquires lock_sock() twice for each new
TCP/MPTCP socket in inet_csk_accept() and __inet_accept().

Let's move memcg operations from inet_csk_accept() to __inet_accept().

Note that SCTP somehow allocates a new socket by sk_alloc() in
sk->sk_prot->accept() and clones fields manually, instead of using
sk_clone_lock().

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().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Link: https://patch.msgid.link/20251014235604.3057003-2-kuniyu@google.com
This commit is contained in:
Kuniyuki Iwashima
2025-10-14 23:54:54 +00:00
committed by Martin KaFai Lau
parent 55db64ddd6
commit 4a997d49d9
2 changed files with 22 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
net/ipv4/af_inet.c
View File

@@ -755,6 +755,28 @@ EXPORT_SYMBOL(inet_stream_connect);
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))) {
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);
}
sock_rps_record_flow(newsk);
WARN_ON(!((1 << newsk->sk_state) &
(TCPF_ESTABLISHED | TCPF_SYN_RECV |

25
net/ipv4/inet_connection_sock.c
View File

@@ -712,31 +712,6 @@ struct sock *inet_csk_accept(struct sock *sk, struct proto_accept_arg *arg)
release_sock(sk);
if (mem_cgroup_sockets_enabled) {
gfp_t gfp = GFP_KERNEL | __GFP_NOFAIL;
int amt = 0;
/* atomically get the memory usage, set and charge the
* newsk->sk_memcg.
*/
lock_sock(newsk);
mem_cgroup_sk_alloc(newsk);
if (mem_cgroup_from_sk(newsk)) {
/* 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);
release_sock(newsk);
}
if (req)
reqsk_put(req);