From nobody Wed Sep 17 20:07:11 2025 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (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 5509723B639 for ; Mon, 21 Jul 2025 20:36:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753130190; cv=none; b=ccOzB1VIZg+z66tjccdeaGRHkQuFeA0XvpCcctIAwISUdYJcrAZLjH/GwmsR0BbTCIbGswm0AACF/Q0aLmvPEQnkaQYwR08lfkYLxWYYPPkYtQJr9n7NXMZMr+VaH2cmOmVVgphhMG8QszZ3Z+ctukLW1uQ22UPUnch03LVEe4w= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753130190; c=relaxed/simple; bh=nQzbvBzPyuVJ5Itkp/dHQSG157Y+6VU++58CwOQo3D4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=GHMrlnijCGoy0TKo8Pp63rDldsabneSsbMTdrv+y5PCF4tectwkF8bMgnY2BQ3rympvNN0DWZ8i+S8TuFaN9WFgHiQmroPUdlrBmEaPPgJlP3tCZAg3PxFMqXsaRTcNqAvOoJU9g++32hruqGkGvPBfiLpuQ5WQEq0QGhrN8qJE= 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=gJ/g/TIv; arc=none smtp.client-ip=209.85.215.201 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="gJ/g/TIv" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-b3f33295703so3788651a12.1 for ; Mon, 21 Jul 2025 13:36:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1753130188; x=1753734988; 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=P67Y4nPe97i+SWJPpvtux7JQJ2xYIXeLm24bM5pwnME=; b=gJ/g/TIv3NGt6dXKJMzipwMafSUEeVK/09h+xafhzgHKS0AVC16XHtftyXrCIW9NCw lrY+8JD6PaI3QANCPxvZB2pO7zNjm7oCh3IMUXMVMw1CDvw6ZK4E44RCZimfF+QegcZz r0y4ozQOvZ+ZT7SGfS02ortRpMCIkAdYgsVtBV8rP6tSJc5tJvHcS8wn6UZJqH1E55fS XUxSsegnJNJv6YkfHKbDjjr/HTGdVx2XslwpVKmEVlo8ymJRHTi6PTu/qj7qZw4She/q oo3C1UxlepqiOjv6hNU7o2XSPIx4Aubse0vpMzS4arVUNckVRf0rjNxHa0d2x6Fwl9kI Kgyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1753130188; x=1753734988; 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=P67Y4nPe97i+SWJPpvtux7JQJ2xYIXeLm24bM5pwnME=; b=hdjsHja3CL/tJoPi6o9hFREtbIihzAnbj5bP1SZElgp6z+1O2ZHnjeR5E0Fcdf+bwe rH16taerlqVADSQwzmSfMtvlfPDM3ywzLcTVt7IKBLnYNwlBUjC1BlTRbQplcCrA2osY OK31ehz3s+iFN9kUAOG1+fMjq2gdwp8dGW+/rBi0+Vw5hvXiSYJ990Q5jAXHnpXRq7mM G/HhnoGr6q3MZytpkrgTKW8hv8e/mRwxrWoVAe2FLHXPkys5e2lD2qVNidOIhY8AJRsF SB4lBGC9/w8AG7AwNmCLmQ3lKCazsr0do3o4PUF+PSecWnEKwAnp0hfikpUGcmLkZJgA 9dTA== X-Forwarded-Encrypted: i=1; AJvYcCULzShNqmYjUhrUeqpTTY2299Po3lrQxO6Kub1iJgsflDM/J/NQf+NhWdHUumFcUArYDlmgtQ==@lists.linux.dev X-Gm-Message-State: AOJu0YxO+0AV3pWzAVGy1KKU87vfWJbdU0B3dTRi+88ebYS+VYajdhId RbgsGk3FUKIHRNXZXHT8a4BftJw944HhlqQ6CrV8OoKoRHsm6++mCDX6HVlJVsde5qDwHuCUJHx IQkeHtQ== X-Google-Smtp-Source: AGHT+IGq5a7mBT9K4l6RJAVl9SuPJnfEZ/pSiUesxpLyMFOJ6g+rCdlI3WLMNPagI5cWYxYgX95XYihYFQ4= X-Received: from pfbhb8.prod.google.com ([2002:a05:6a00:8588:b0:748:55b9:ffbe]) (user=kuniyu job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:e613:b0:21f:4631:811c with SMTP id adf61e73a8af0-2390dba61fbmr26139263637.19.1753130188582; Mon, 21 Jul 2025 13:36:28 -0700 (PDT) Date: Mon, 21 Jul 2025 20:35:20 +0000 In-Reply-To: <20250721203624.3807041-1-kuniyu@google.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250721203624.3807041-1-kuniyu@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250721203624.3807041-2-kuniyu@google.com> Subject: [PATCH v1 net-next 01/13] 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 Cc: Simon Horman , Geliang Tang , Muchun Song , 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 | 7 +++++++ mm/memcontrol.c | 10 ++++++++++ net/mptcp/subflow.c | 11 +++-------- 3 files changed, 20 insertions(+), 8 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 87b6688f124a7..d8319ad5e8ea7 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -1602,6 +1602,8 @@ 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); + static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *mem= cg) { #ifdef CONFIG_MEMCG_V1 @@ -1623,6 +1625,11 @@ 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 70fdeda1120b3..54eb25d8d555c 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5090,6 +5090,16 @@ 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 1802bc5435a1a..f21d90fb1a19d 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1716,19 +1716,14 @@ 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 2.50.0.727.gbf7dc18ff4-goog