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AJvYcCWRRHN7i/vsCnhGtWluP4wxXwcQG9XVtCnL6eRYUvJFIjJDxaR+NTn46k33id9lSheO2SnmX07BzA==@kvack.org X-Gm-Message-State: AOJu0YxIaElANG5Du31ydYVeq+SK75z04P+YaaaO2G1Bh+vfGxHFFrnL DABSBOxCmURRPjMY9V+yxE6nwgrQb2cq1Lr3pHrFn48glde/YAfy+jX8Qxz5V8bpz5iz9D9MkWQ inZTUC3Zo1f9No/zC6cAsB1wN0rxyuoTT/S8/aPkd X-Gm-Gg: ASbGnct4y9B4bJm85jzba4hhR8pOqy6607c49nA+cs1Fey/9e3RT4rlB24hlpvFiXbW 2TGu04HprDTR0rsjdbKfT2Z57T5j76kk9P726J6XK33Zk1XeLFg2QL6eDkglfcgBCy0Axnhv/DY 5FChoWHQpl6ReF4NOZ6FkZmY6HmexkdFsdQdLUcuTkaVsGJ5AqPkwe/uONBz62KgSpxKEIkTJry Sct+5qvJXmKQyLL X-Google-Smtp-Source: AGHT+IHQ1F/XNS6EEtYUtpk/olOEZA/Va6cGJiS4hiBQzXMnDQFWPRfhrIeUbeCE+v3wAGiJbMRJO1Xiv4/aKrsvrGs= X-Received: by 2002:ac8:5d4c:0:b0:49b:eb1d:18ad with SMTP id d75a77b69052e-4ab93dbed7cmr383658691cf.41.1753194620995; Tue, 22 Jul 2025 07:30:20 -0700 (PDT) MIME-Version: 1.0 References: <20250721203624.3807041-1-kuniyu@google.com> <20250721203624.3807041-2-kuniyu@google.com> In-Reply-To: <20250721203624.3807041-2-kuniyu@google.com> From: Eric Dumazet Date: Tue, 22 Jul 2025 07:30:09 -0700 X-Gm-Features: Ac12FXzou9QrF6H0tl3cLlJlr49JVeNU-g_6k8oOer2kAmc56xaiC2vvAezaFAw Message-ID: Subject: Re: [PATCH v1 net-next 01/13] mptcp: Fix up subflow's memcg when CONFIG_SOCK_CGROUP_DATA=n. To: Kuniyuki Iwashima Cc: "David S. Miller" , Jakub Kicinski , Neal Cardwell , Paolo Abeni , Willem de Bruijn , Matthieu Baerts , Mat Martineau , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Andrew Morton , Simon Horman , Geliang Tang , Muchun Song , Kuniyuki Iwashima , netdev@vger.kernel.org, mptcp@lists.linux.dev, cgroups@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 61E3B8000F X-Stat-Signature: yt4rcno11qgctttwuoebjh759hz8edxs X-HE-Tag: 1753194622-789934 X-HE-Meta: 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 c6aik6IB w6XXcZ/6+EK75plTMDewLmDjQHAUxGDgjo1IPgpPnXEK/grSLcCXF02KQ4WQjTfw0aZHWsujiYU/37tz78TGIbIj98LN5gkd0xeDQyr7w8vQ3OMGFTIcYaaYEzPzxGMOp5raX0SlSFkB/LBGHuQzybDG0Blm10Z1Atrw969MK+e2FjHCNs2Rzzuo+jNa0x7FTC6kGAqKBfgKgzCQNyOkya1ojtIcYpTvlu1ujJt7YZOPcElVIUk5a+qkfbD8uqPWXh7d3aUstdXAFvhE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 21, 2025 at 1:36=E2=80=AFPM Kuniyuki Iwashima wrote: > > When sk_alloc() allocates a socket, mem_cgroup_sk_alloc() sets > sk->sk_memcg based on the current task. > > MPTCP subflow socket creation is triggered from userspace or > an in-kernel worker. > > In the latter case, sk->sk_memcg is not what we want. So, we fix > it up from the parent socket's sk->sk_memcg in mptcp_attach_cgroup(). > > Although the code is placed under #ifdef CONFIG_MEMCG, it is buried > under #ifdef CONFIG_SOCK_CGROUP_DATA. > > The two configs are orthogonal. If CONFIG_MEMCG is enabled without > CONFIG_SOCK_CGROUP_DATA, the subflow's memory usage is not charged > correctly. > > Let's move the code out of the wrong ifdef guard. > > Note that sk->sk_memcg is freed in sk_prot_free() and the parent > sk holds the refcnt of memcg->css here, so we don't need to use > css_tryget(). > > Fixes: 3764b0c5651e3 ("mptcp: attach subflow socket to parent cgroup") > Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet