From nobody Wed Sep 17 20:07:13 2025 Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04E5A2BE637 for ; Mon, 11 Aug 2025 17:31:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754933494; cv=none; b=Jvh3lyiFLcFX+YlrK/njBLlHcJiJI9X7ghpFm9dN+UKzBheZ7aRfb8/w6BbxOtEtzLdrosaNytXctfeuZQMIEDlWUmW26L8JJVnm94Eq0geyEQlNBNOuXs9xxfZkrXKr1Frbym63fmlVPtC1Lmf1p9EbLM0/5+YHaygwK8g7EOo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754933494; c=relaxed/simple; bh=RraDdlXe6ciaP6cYzKFgCu43EUAwSOZf2SxKtlzfM/U=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=cosozWqgZUfSIc1R6FCNqxTY/2jjUuxKmmuf1CIy86usd3DVLTgHkp3p/OqTXT3sk227vVQBZatgMrxnOZfVz+Ba3sF58gkXGGodoya9g0VSg2G7TtBHi/aQobQYbOvCTY2kaC/sm1pP+pMeuAaMfJab/OkFwCgNccOSOC7mwCQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--kuniyu.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=EMk5Gmfo; arc=none smtp.client-ip=209.85.210.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--kuniyu.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="EMk5Gmfo" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-76bcd829ff1so4350461b3a.1 for ; Mon, 11 Aug 2025 10:31:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1754933492; x=1755538292; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=zi8XD71jgjXMWJD0GQyZXVIV2qpgVtIymKBEzG9L4F4=; b=EMk5GmfoCbwVyTiFVLYqGiDQMmGXtga+WaoXRWT20c/maSjlT9kdaGI0Kfcij2wL9k n92bqFm50a1dZzMy1Z7aMpp4ttiZLSA+IpwAExRZisV0ZXrcK+kVQY+/PVgSFWjJKlYT ceX2RLWq7GAGZE0kRqgRF83FxXifETGvK3LtfqBqhCbZd57O3hEvOZv5gYbv4E840c1J 1DQU/hK7mvb5asIVzXvRU9UD8rd0PtEbBFJWdRSTSns+KSdQBzmR1jFjLghCd2/XHTia 4IEAqCjUgdj1qJjc08tXK5tMPhP/m/KPr/WON5R4doayNOVjwOE35cSZ7k9hX5FDd6Og 5j+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1754933492; x=1755538292; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=zi8XD71jgjXMWJD0GQyZXVIV2qpgVtIymKBEzG9L4F4=; b=InGhZIpQ3owT9vVXqeOZgUEq2XTK1Jd6XvuysH9FW6qrYyh0Dxknsn7+WZ8JQlTXCZ UlXKJJO3YwzMaSO0lg8QkSj8sD9DO755zmsK4ocbWATT/DYqAiNdsoNOM9MNSchcKwJM lNwsAERiKfVYL+ai8o0c/ckDeBRKsGFmFMzom9vEvVL+qVjmKQ2LWgIDoIZ9h9MP+yvP Qk+wyAjTa3Hd+vSL8xP2eMyyY4JbX2VuyL/0UCZnccx6+Ty4DqLQHFUJ3XmBSTxExL3/ iyAFafYlqPSt5JvB6NkVH3PP77dK5oa6cu4jmNa8sg/8pcVkVkrsX7oEc1vzIhY5s1hd 6akg== X-Forwarded-Encrypted: i=1; AJvYcCX3yRj07loAqjKwk54i9ygd7GasRcooe1u990RpX2YF/yy1Yc1Sa1LGFBFQ93ipU41o+A+q8Q==@lists.linux.dev X-Gm-Message-State: AOJu0YyGEn/v6MLiovb6xbmXxFohQ17pNOL77inanFNZzKsDMUaBC+Nr nCpAMZrJ0+aPE7eSClUeQ6lY/jElSG7OeM2zlnLxYySSzMuA9TbGYtCTakEdTd5edbrPmV2AYv8 1cvZUDQ== X-Google-Smtp-Source: AGHT+IHo2yNLTeCJQnssS8cRVh9LBZumUnUBfB6vxpMn5hTdAQ6pUphTOW3txkt3Suq2A0M516UNLF041yo= X-Received: from pftb15.prod.google.com ([2002:a05:6a00:2cf:b0:76b:ca57:9538]) (user=kuniyu job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:2d1b:b0:748:ffaf:9b53 with SMTP id d2e1a72fcca58-76c461af0ebmr17005996b3a.16.1754933492214; Mon, 11 Aug 2025 10:31:32 -0700 (PDT) Date: Mon, 11 Aug 2025 17:30:29 +0000 In-Reply-To: <20250811173116.2829786-1-kuniyu@google.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250811173116.2829786-1-kuniyu@google.com> X-Mailer: git-send-email 2.51.0.rc0.155.g4a0f42376b-goog Message-ID: <20250811173116.2829786-2-kuniyu@google.com> Subject: [PATCH v2 net-next 01/12] mptcp: Fix up subflow's memcg when CONFIG_SOCK_CGROUP_DATA=n. From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Neal Cardwell , Paolo Abeni , Willem de Bruijn , Matthieu Baerts , Mat Martineau , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Andrew Morton , "=?UTF-8?q?Michal=20Koutn=C3=BD?=" , Tejun Heo Cc: Simon Horman , Geliang Tang , Muchun Song , Mina Almasry , Kuniyuki Iwashima , Kuniyuki Iwashima , netdev@vger.kernel.org, mptcp@lists.linux.dev, cgroups@vger.kernel.org, linux-mm@kvack.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 --- include/linux/memcontrol.h | 6 ++++++ mm/memcontrol.c | 10 ++++++++++ net/mptcp/subflow.c | 11 +++-------- 3 files changed, 19 insertions(+), 8 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 785173aa0739..25921fbec685 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -1604,6 +1604,7 @@ extern struct static_key_false memcg_sockets_enabled_= key; #define mem_cgroup_sockets_enabled static_branch_unlikely(&memcg_sockets_e= nabled_key) void mem_cgroup_sk_alloc(struct sock *sk); void mem_cgroup_sk_free(struct sock *sk); +void mem_cgroup_sk_inherit(const struct sock *sk, struct sock *newsk); =20 #if BITS_PER_LONG < 64 static inline void mem_cgroup_set_socket_pressure(struct mem_cgroup *memcg) @@ -1661,6 +1662,11 @@ void reparent_shrinker_deferred(struct mem_cgroup *m= emcg); #define mem_cgroup_sockets_enabled 0 static inline void mem_cgroup_sk_alloc(struct sock *sk) { }; static inline void mem_cgroup_sk_free(struct sock *sk) { }; + +static inline void mem_cgroup_sk_inherit(const struct sock *sk, struct soc= k *newsk) +{ +} + static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *mem= cg) { return false; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8dd7fbed5a94..08c6e06750ac 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5024,6 +5024,16 @@ void mem_cgroup_sk_free(struct sock *sk) css_put(&sk->sk_memcg->css); } =20 +void mem_cgroup_sk_inherit(const struct sock *sk, struct sock *newsk) +{ + if (sk->sk_memcg =3D=3D newsk->sk_memcg) + return; + + mem_cgroup_sk_free(newsk); + css_get(&sk->sk_memcg->css); + newsk->sk_memcg =3D sk->sk_memcg; +} + /** * mem_cgroup_charge_skmem - charge socket memory * @memcg: memcg to charge diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 3f1b62a9fe88..6fb635a95baf 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1717,19 +1717,14 @@ static void mptcp_attach_cgroup(struct sock *parent= , struct sock *child) /* only the additional subflows created by kworkers have to be modified */ if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=3D cgroup_id(sock_cgroup_ptr(child_skcd))) { -#ifdef CONFIG_MEMCG - struct mem_cgroup *memcg =3D parent->sk_memcg; - - mem_cgroup_sk_free(child); - if (memcg && css_tryget(&memcg->css)) - child->sk_memcg =3D memcg; -#endif /* CONFIG_MEMCG */ - cgroup_sk_free(child_skcd); *child_skcd =3D *parent_skcd; cgroup_sk_clone(child_skcd); } #endif /* CONFIG_SOCK_CGROUP_DATA */ + + if (mem_cgroup_sockets_enabled && parent->sk_memcg) + mem_cgroup_sk_inherit(parent, child); } =20 static void mptcp_subflow_ops_override(struct sock *ssk) --=20 2.51.0.rc0.155.g4a0f42376b-goog