From nobody Wed Sep 17 19:50:05 2025 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (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 49D6A29C35F for ; Fri, 15 Aug 2025 20:17:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755289057; cv=none; b=omJEHRHJKUziIybM6FcraIFLJcqNiMWGJIrGAvZbDqXsAtuOLGjo5ZauDOWpnGzu+Yd/wooxo0cMI6uCj5mjgCGD0WF8FuczfkaUXEhETYrG9In4JyAlMWY2kxIJVppRwXQPrF7AZTLtm3ADN6YwXt2UCC99DIRnTec0jG+MATs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755289057; c=relaxed/simple; bh=twkMnoDWF2WEDu7aGDJTpR79gYT+9DDfGd76WM0w1Qs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ZSQ554lUZxddavnm88dVb9Tit4OLKXZOGWhpg4g6TW+alhIjohBwLIU5coU3hu84tcT10+EiDEH8CbaK/5ibyxbFHw3ug4+lp00JNA8aWf2Qa0YY++wO8kAulaV+5uPFXzjuM3SNN3NW58xhREPgAJRoGCZ+ovWGhTbIAlTd6Gg= 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=w6eNopz2; arc=none smtp.client-ip=209.85.216.73 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="w6eNopz2" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-32326e6c74eso2418080a91.3 for ; Fri, 15 Aug 2025 13:17:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1755289055; x=1755893855; 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=QmaKJoKwHw82XyXX/d5iEOMfvSvHT9xY0QGibQUjsoM=; b=w6eNopz2cIAw22P6Kfei9mwS3g/IuOMWfJWSxlFeTTdOZ0ux7YbZCxo86Ks/C7vQ6U zm1sxrKhmZSNgcFVzqty8dUJIKGS+vRM7WIiU5TTciay0XvIyCWdVetDieXnn4/Z6Izl FCNuaAVFS3VDXrL5C3rT6j38tOcNtiak6GwT6kZrUD4j93MnAjIDE+yoYFXJSLsMtgkK LF+X9eO3331nvusWJ2GELL6mHIxyERzNYNbsyCbHjXqa6+p/Pxafg7+CW7lmkaWn0o7U hROF2DLZcLuIePGb8iS/O50fKGC3pF0/FMHbmfQQrkaeUf9gplYuLVpOSzbXe7f2fgVv oG8Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755289055; x=1755893855; 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=QmaKJoKwHw82XyXX/d5iEOMfvSvHT9xY0QGibQUjsoM=; b=l8HFGUUJlCqfs0xCB6TB9da2HXXDrtM7hg4PTBSgBeq29GGEkiJTtYMbIgGJMyX6xn 1heq+F3CK+uWaQQ5dtiZ0vK+GnI607Ghh7/K2O/ShtYYRJZ62DKPEPL5U2KGLtlm/AWu YFGxUAgjX+xS29Dh3s/KobIXl5fT9SCnafMRi9fNeglshug6DJdf9xwiTemt634mxPa2 OEVbaDVyWgiQoMCNAaHq4JLq7SR/DCmg99evekol4N4DwXa+mfztem0lAVexv/uXqsys 1LbCisObQM73DLBZ/DTcZQoDG+2QxvUtXi7sv5LZXry3OGZK+DsrK+KCO9zDlNt2vKUB U3Ow== X-Forwarded-Encrypted: i=1; AJvYcCUWZuTru71/EK28YGqY5UAWF8dKrym08UXFgdVgT6Gndko2oWWItixY1XshCtPJ0U09qfJZRw==@lists.linux.dev X-Gm-Message-State: AOJu0Yx8smw1itNtQ/N6igKPsMftnT0sTkfgOjMqBF6yQJZVEDHCAulG cBIyHqmlRpN4iwZqWvZpWYiGkfGTOBh0FewGGIj9o0Qn58ee6fqcxuHZgZlv8hYab4Sjm3A60cz 7COdCRQ== X-Google-Smtp-Source: AGHT+IFGdAKK5lsJCVHw32dBU/IQeIjE5FuMNI2s+BoaP+r58/XH4MUq0ZbtlmMZS9ZWWTLlSD916PektfI= X-Received: from pjbtd11.prod.google.com ([2002:a17:90b:544b:b0:31f:2a78:943]) (user=kuniyu job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:55c7:b0:321:a2d4:11b6 with SMTP id 98e67ed59e1d1-3234db8e481mr643458a91.12.1755289055548; Fri, 15 Aug 2025 13:17:35 -0700 (PDT) Date: Fri, 15 Aug 2025 20:16:09 +0000 In-Reply-To: <20250815201712.1745332-1-kuniyu@google.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250815201712.1745332-1-kuniyu@google.com> X-Mailer: git-send-email 2.51.0.rc1.163.g2494970778-goog Message-ID: <20250815201712.1745332-2-kuniyu@google.com> Subject: [PATCH v5 net-next 01/10] 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 Acked-by: Matthieu Baerts (NGI0) Acked-by: Shakeel Butt --- include/linux/memcontrol.h | 6 ++++++ mm/memcontrol.c | 13 +++++++++++++ net/mptcp/subflow.c | 11 +++-------- 3 files changed, 22 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..46713b9ece06 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5024,6 +5024,19 @@ 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); + + if (sk->sk_memcg) + 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..c8a7e4b59db1 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) + mem_cgroup_sk_inherit(parent, child); } =20 static void mptcp_subflow_ops_override(struct sock *ssk) --=20 2.51.0.rc1.163.g2494970778-goog