From: Martin KaFai Lau <martin.lau@linux.dev>
To: Kuniyuki Iwashima <kuniyu@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shakeel Butt <shakeel.butt@linux.dev>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Stanislav Fomichev <sdf@fomichev.me>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Neal Cardwell <ncardwell@google.com>,
Willem de Bruijn <willemb@google.com>,
Mina Almasry <almasrymina@google.com>,
Kuniyuki Iwashima <kuni1840@gmail.com>,
bpf@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH v10 bpf-next/net 2/6] net-memcg: Allow decoupling memcg from global protocol memory accounting.
Date: Sat, 27 Sep 2025 07:49:45 -0700 [thread overview]
Message-ID: <f81fa440-4a89-4d80-9707-86db76141969@linux.dev> (raw)
In-Reply-To: <CAAVpQUDxSwjegw1UgieGOF+YGF=j2_FK=M1ZEKP1KGdtCdEBkw@mail.gmail.com>
On 9/25/25 3:40 PM, Kuniyuki Iwashima wrote:
> On Fri, Sep 19, 2025 at 10:25 PM Shakeel Butt <shakeel.butt@linux.dev> wrote:
>>
>> On Sat, Sep 20, 2025 at 12:07:16AM +0000, Kuniyuki Iwashima wrote:
>>> Some protocols (e.g., TCP, UDP) implement memory accounting for socket
>>> buffers and charge memory to per-protocol global counters pointed to by
>>> sk->sk_proto->memory_allocated.
>>>
>>> If a socket has sk->sk_memcg, this memory is also charged to memcg as
>>> "sock" in memory.stat.
>>>
>>> We do not need to pay costs for two orthogonal memory accounting
>>> mechanisms. A microbenchmark result is in the subsequent bpf patch.
>>>
>>> Let's decouple sockets under memcg from the global per-protocol memory
>>> accounting if mem_cgroup_sk_exclusive() returns true.
>>>
>>> Note that this does NOT disable memcg, but rather the per-protocol one.
>>>
>>> mem_cgroup_sk_exclusive() starts to return true in the following patches,
>>> and then, the per-protocol memory accounting will be skipped.
>>>
>>> In __inet_accept(), we need to reclaim counts that are already charged
>>> for child sockets because we do not allocate sk->sk_memcg until accept().
>>>
>>> trace_sock_exceed_buf_limit() will always show 0 as accounted for the
>>> memcg-exclusive sockets, but this can be obtained in memory.stat.
>>>
>>> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
>>> Nacked-by: Johannes Weiner <hannes@cmpxchg.org>
The patch cannot move on (i.e. land or respin) until the NACK concern is resolved.
>>
>> This looks good to me now, let's ask Johannes to take a look again and if
>> he still has any concerns.
>>
>> Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
>
> Hi Johannes,
>
> It would be really appreciated if you have a look again.
>
Hi Johannes,
Can you take a look if the clarified reason in the commit message has addressed
the concern ?
Thanks,
Martin
next prev parent reply other threads:[~2025-09-27 14:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-20 0:07 [PATCH v10 bpf-next/net 0/6] bpf: Allow decoupling memcg from sk->sk_prot->memory_allocated Kuniyuki Iwashima
2025-09-20 0:07 ` [PATCH v10 bpf-next/net 1/6] tcp: Save lock_sock() for memcg in inet_csk_accept() Kuniyuki Iwashima
2025-09-20 0:07 ` [PATCH v10 bpf-next/net 2/6] net-memcg: Allow decoupling memcg from global protocol memory accounting Kuniyuki Iwashima
2025-09-20 5:25 ` Shakeel Butt
2025-09-25 22:40 ` Kuniyuki Iwashima
2025-09-27 14:49 ` Martin KaFai Lau [this message]
2025-09-20 0:07 ` [PATCH v10 bpf-next/net 3/6] net-memcg: Introduce net.core.memcg_exclusive sysctl Kuniyuki Iwashima
2025-09-20 5:35 ` Shakeel Butt
2025-09-20 6:22 ` Kuniyuki Iwashima
2025-09-23 0:54 ` Shakeel Butt
2025-09-23 1:03 ` Kuniyuki Iwashima
2025-09-23 1:26 ` Kuniyuki Iwashima
2025-09-25 22:52 ` Shakeel Butt
2025-09-20 0:07 ` [PATCH v10 bpf-next/net 4/6] bpf: Support bpf_setsockopt() for BPF_CGROUP_INET_SOCK_CREATE Kuniyuki Iwashima
2025-09-20 0:07 ` [PATCH v10 bpf-next/net 5/6] bpf: Introduce SK_BPF_MEMCG_FLAGS and SK_BPF_MEMCG_EXCLUSIVE Kuniyuki Iwashima
2025-09-20 0:07 ` [PATCH v10 bpf-next/net 6/6] selftest: bpf: Add test for SK_MEMCG_EXCLUSIVE Kuniyuki Iwashima
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