From: Johannes Weiner <hannes@cmpxchg.org>
To: Kuniyuki Iwashima <kuniyu@google.com>
Cc: "David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Neal Cardwell" <ncardwell@google.com>,
"Paolo Abeni" <pabeni@redhat.com>,
"Willem de Bruijn" <willemb@google.com>,
"Matthieu Baerts" <matttbe@kernel.org>,
"Mat Martineau" <martineau@kernel.org>,
"Michal Hocko" <mhocko@kernel.org>,
"Roman Gushchin" <roman.gushchin@linux.dev>,
"Shakeel Butt" <shakeel.butt@linux.dev>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Michal Koutný" <mkoutny@suse.com>, "Tejun Heo" <tj@kernel.org>,
"Simon Horman" <horms@kernel.org>,
"Geliang Tang" <geliang@kernel.org>,
"Muchun Song" <muchun.song@linux.dev>,
"Mina Almasry" <almasrymina@google.com>,
"Kuniyuki Iwashima" <kuni1840@gmail.com>,
netdev@vger.kernel.org, mptcp@lists.linux.dev,
cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v3 net-next 12/12] net-memcg: Decouple controlled memcg from global protocol memory accounting.
Date: Wed, 13 Aug 2025 09:00:09 -0400 [thread overview]
Message-ID: <20250813130009.GA114408@cmpxchg.org> (raw)
In-Reply-To: <20250812175848.512446-13-kuniyu@google.com>
On Tue, Aug 12, 2025 at 05:58:30PM +0000, Kuniyuki Iwashima wrote:
> If all workloads were guaranteed to be controlled under memcg, the issue
> could be worked around by setting tcp_mem[0~2] to UINT_MAX.
>
> In reality, this assumption does not always hold, and processes that
> belong to the root cgroup or opt out of memcg can consume memory up to
> the global limit, becoming a noisy neighbour.
As per the last thread, this is not a supported usecase. Opting out of
memcg coverage for individual cgroups is a self-inflicted problem and
misconfiguration. There is *no* memory isolation *at all* on such
containers. Maybe their socket buffers is the only thing that happens
to matter to *you*, but this is in no way a generic, universal,
upstreamable solution. Knob or auto-detection is not the issue.
Nacked-by: Johannes Weiner <hannes@cmpxchg.org>
next prev parent reply other threads:[~2025-08-13 13:00 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-12 17:58 [PATCH v3 net-next 00/12] net-memcg: Decouple controlled memcg from sk->sk_prot->memory_allocated Kuniyuki Iwashima
2025-08-12 17:58 ` [PATCH v3 net-next 01/12] mptcp: Fix up subflow's memcg when CONFIG_SOCK_CGROUP_DATA=n Kuniyuki Iwashima
2025-08-13 8:54 ` Matthieu Baerts
2025-08-14 12:30 ` Michal Koutný
2025-08-14 19:17 ` Kuniyuki Iwashima
2025-08-12 17:58 ` [PATCH v3 net-next 02/12] mptcp: Use tcp_under_memory_pressure() in mptcp_epollin_ready() Kuniyuki Iwashima
2025-08-13 8:54 ` Matthieu Baerts
2025-08-12 17:58 ` [PATCH v3 net-next 03/12] tcp: Simplify error path in inet_csk_accept() Kuniyuki Iwashima
2025-08-12 17:58 ` [PATCH v3 net-next 04/12] net: Call trace_sock_exceed_buf_limit() for memcg failure with SK_MEM_RECV Kuniyuki Iwashima
2025-08-12 17:58 ` [PATCH v3 net-next 05/12] net: Clean up __sk_mem_raise_allocated() Kuniyuki Iwashima
2025-08-12 17:58 ` [PATCH v3 net-next 06/12] net-memcg: Introduce mem_cgroup_from_sk() Kuniyuki Iwashima
2025-08-13 1:44 ` Roman Gushchin
2025-08-12 17:58 ` [PATCH v3 net-next 07/12] net-memcg: Introduce mem_cgroup_sk_enabled() Kuniyuki Iwashima
2025-08-13 1:46 ` Roman Gushchin
2025-08-12 17:58 ` [PATCH v3 net-next 08/12] net-memcg: Pass struct sock to mem_cgroup_sk_(un)?charge() Kuniyuki Iwashima
2025-08-13 1:47 ` Roman Gushchin
2025-08-12 17:58 ` [PATCH v3 net-next 09/12] net-memcg: Pass struct sock to mem_cgroup_sk_under_memory_pressure() Kuniyuki Iwashima
2025-08-13 1:49 ` Roman Gushchin
2025-08-13 1:49 ` Roman Gushchin
2025-08-12 17:58 ` [PATCH v3 net-next 10/12] net: Define sk_memcg under CONFIG_MEMCG Kuniyuki Iwashima
2025-08-12 17:58 ` [PATCH v3 net-next 11/12] net-memcg: Store MEMCG_SOCK_ISOLATED in sk->sk_memcg Kuniyuki Iwashima
2025-08-12 17:58 ` [PATCH v3 net-next 12/12] net-memcg: Decouple controlled memcg from global protocol memory accounting Kuniyuki Iwashima
2025-08-13 1:57 ` Roman Gushchin
2025-08-13 5:32 ` Kuniyuki Iwashima
2025-08-13 7:11 ` Shakeel Butt
2025-08-13 18:19 ` Kuniyuki Iwashima
2025-08-13 20:53 ` Shakeel Butt
2025-08-14 0:54 ` Martin KaFai Lau
2025-08-14 4:34 ` Kuniyuki Iwashima
2025-08-14 17:10 ` Shakeel Butt
2025-08-13 13:00 ` Johannes Weiner [this message]
2025-08-13 18:43 ` Kuniyuki Iwashima
2025-08-13 20:21 ` Johannes Weiner
2025-08-12 20:30 ` [PATCH v3 net-next 00/12] net-memcg: Decouple controlled memcg from sk->sk_prot->memory_allocated MPTCP CI
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