From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 123A2241695; Mon, 13 Oct 2025 15:30:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760369450; cv=none; b=Ap0s2JqdytKwPRR7Y7EvviSOwFwpUpkN7Rb+Cqs+NfISmFazWWIWs4LhCBWcy8/S3LsU/B//sGMbGWX5DRr19JY7fPjAbq3Q4sdoQZuAmdOn3ZLMgMrSKUmVNAlLxlzClPqM7LhvVH8Hn4qx0AvvzDB325kjswz1kNRkHvvMceQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760369450; c=relaxed/simple; bh=zRn4qX8IdfONMNz0hzCnDhdWAkGw/dj3ewPQqKt6iW4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=U2tLNg7mkC3t1JoQzON+KR2TZUrPb5ZKJcj+VdPK+MNcAoyFDaYDigjDmxJI1FwaRK9YSCJ9RuMC5d6BteZYfHB4vx6wB/pFiX1R2UH7+Uw2unhEa+NhQzZdfqANPmv70ge1TIOr1bZSVGZonjYhhdRnKVElpvc3cEAdD7nQL5E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dvuk0pyw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="dvuk0pyw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90D11C4CEE7; Mon, 13 Oct 2025 15:30:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1760369449; bh=zRn4qX8IdfONMNz0hzCnDhdWAkGw/dj3ewPQqKt6iW4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dvuk0pywV+WffOnQ4GYhvUxZnth9+z1JftUev/1xT2uGDg2aFfD2spTaOIlm0i0R7 mE5Sg2Sesfjx03k9+jCYNO07vNBCvw2NKwsup14VF2KoKu8WrfNNPqlGNQDCv4EAVL jCoGyCnBTOP2G22NdLP3rPHSnQW35UiWBJxoo34o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Eric Dumazet , "Matthieu Baerts (NGI0)" , Shakeel Butt , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.17 251/563] mptcp: Fix up subflows memcg when CONFIG_SOCK_CGROUP_DATA=n. Date: Mon, 13 Oct 2025 16:41:52 +0200 Message-ID: <20251013144420.375576423@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251013144411.274874080@linuxfoundation.org> References: <20251013144411.274874080@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit 68889dfd547bd8eabc5a98b58475d7b901cf5129 ] 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 Link: https://patch.msgid.link/20250815201712.1745332-2-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- 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 785173aa0739c..25921fbec6856 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_enabled_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); #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 *memcg); #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 sock *newsk) +{ +} + static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg) { return false; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8dd7fbed5a942..46713b9ece063 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); } +void mem_cgroup_sk_inherit(const struct sock *sk, struct sock *newsk) +{ + if (sk->sk_memcg == newsk->sk_memcg) + return; + + mem_cgroup_sk_free(newsk); + + if (sk->sk_memcg) + css_get(&sk->sk_memcg->css); + + newsk->sk_memcg = 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 f31a3a79531a2..e8325890a3223 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1721,19 +1721,14 @@ 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)) != cgroup_id(sock_cgroup_ptr(child_skcd))) { -#ifdef CONFIG_MEMCG - struct mem_cgroup *memcg = parent->sk_memcg; - - mem_cgroup_sk_free(child); - if (memcg && css_tryget(&memcg->css)) - child->sk_memcg = memcg; -#endif /* CONFIG_MEMCG */ - cgroup_sk_free(child_skcd); *child_skcd = *parent_skcd; cgroup_sk_clone(child_skcd); } #endif /* CONFIG_SOCK_CGROUP_DATA */ + + if (mem_cgroup_sockets_enabled) + mem_cgroup_sk_inherit(parent, child); } static void mptcp_subflow_ops_override(struct sock *ssk) -- 2.51.0