netdev - [PATCH v3 bpf-next/net 0/5] bpf: Allow decoupling memcg from sk->sk_prot->memory

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Message-ID: <20250826183940.3310118-1-kuniyu@google.com>
Date: Tue, 26 Aug 2025 18:38:06 +0000
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: Alexei Starovoitov <ast@...nel.org>, Andrii Nakryiko <andrii@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Martin KaFai Lau <martin.lau@...ux.dev>
Cc: John Fastabend <john.fastabend@...il.com>, Stanislav Fomichev <sdf@...ichev.me>, 
	Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>, 
	Roman Gushchin <roman.gushchin@...ux.dev>, Shakeel Butt <shakeel.butt@...ux.dev>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Neal Cardwell <ncardwell@...gle.com>, Willem de Bruijn <willemb@...gle.com>, 
	Mina Almasry <almasrymina@...gle.com>, Kuniyuki Iwashima <kuniyu@...gle.com>, 
	Kuniyuki Iwashima <kuni1840@...il.com>, bpf@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH v3 bpf-next/net 0/5] bpf: Allow decoupling memcg from sk->sk_prot->memory_allocated.

Some protocols (e.g., TCP, UDP) have their own memory accounting for
socket buffers and charge memory to global per-protocol counters such
as /proc/net/ipv4/tcp_mem.

When running under a non-root cgroup, this memory is also charged to
the memcg as sock in memory.stat.

Sockets of such protocols are still subject to the global limits,
thus affected by a noisy neighbour outside cgroup.

This makes it difficult to accurately estimate and configure appropriate
global limits.

This series allows decoupling memcg from the global memory accounting
if socket is configured as such by BPF prog.

This simplifies the memcg configuration while keeping the global limits
within a reasonable range, which is only 10% of the physical memory by
default.

Overview of the series:

  patch 1 & 2 are prep
  patch 3 intorduces SK_BPF_MEMCG_SOCK_ISOLATED for bpf_setsockopt()
  patch 4 decouples memcg from sk_prot->memory_allocated based on the flag
  patch 5 is selftest


Changes:
  v3:
    * Drop accept() hook and use BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB instead
    * Patch 1
      * Merge if blocks
    * Patch2
      * Drop bpf_func_proto for accept()
    * Patch 3
      * Allow flagging without sk->sk_memcg
      * Inherit SK_BPF_MEMCG_SOCK_ISOLATED in __inet_accept()

  v2: https://lore.kernel.org/bpf/20250825204158.2414402-1-kuniyu@google.com/
    * Patch 2
      * Define BPF_CGROUP_RUN_PROG_INET_SOCK_ACCEPT() when CONFIG_CGROUP_BPF=n
    * Patch 5
      * Make 2 new bpf_func_proto static
    * Patch 6
      * s/mem_cgroup_sk_set_flag/mem_cgroup_sk_set_flags/ when CONFIG_MEMCG=n
      * Use finer CONFIG_CGROUP_BPF instead of CONFIG_BPF_SYSCALL for ifdef

  v1: https://lore.kernel.org/netdev/20250822221846.744252-1-kuniyu@google.com/



Kuniyuki Iwashima (5):
  tcp: Save lock_sock() for memcg in inet_csk_accept().
  bpf: Support bpf_setsockopt() for BPF_CGROUP_INET_SOCK_CREATE.
  bpf: Introduce SK_BPF_MEMCG_FLAGS and SK_BPF_MEMCG_SOCK_ISOLATED.
  net-memcg: Allow decoupling memcg from global protocol memory
    accounting.
  selftest: bpf: Add test for SK_BPF_MEMCG_SOCK_ISOLATED.

 include/net/proto_memory.h                    |  15 +-
 include/net/sock.h                            |  48 ++++
 include/net/tcp.h                             |  10 +-
 include/uapi/linux/bpf.h                      |   6 +
 net/core/filter.c                             |  52 ++++-
 net/core/sock.c                               |  64 +++--
 net/ipv4/af_inet.c                            |  37 +++
 net/ipv4/inet_connection_sock.c               |  26 +--
 net/ipv4/tcp.c                                |   3 +-
 net/ipv4/tcp_output.c                         |  10 +-
 net/mptcp/protocol.c                          |   3 +-
 net/tls/tls_device.c                          |   4 +-
 tools/include/uapi/linux/bpf.h                |   6 +
 .../selftests/bpf/prog_tests/sk_memcg.c       | 218 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/sk_memcg.c  |  30 +++
 15 files changed, 475 insertions(+), 57 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/sk_memcg.c
 create mode 100644 tools/testing/selftests/bpf/progs/sk_memcg.c

-- 
2.51.0.318.gd7df087d1a-goog