From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.white.stw.pengutronix.de (mx1.white.stw.pengutronix.de [185.203.200.13]) (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 CB3F4443E29; Wed, 29 Jul 2026 10:29:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.203.200.13 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785320978; cv=none; b=jeKzUN82pIpt7yxkVJeKWlBHfa2stvR/0Uu86YJmRbHClsRDITf8snyZSyHr7uRTx1bIDLYjM9NwxJrkU5YoOWsVHhfxPP5RXjO/3/7OViu5a3bzqu14kPkjq3m8jLkdtwKdNFbwDpOsLvY946Avfj76AzKkoPfMfNWvvdzqrhE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785320978; c=relaxed/simple; bh=c4+wKD74ldYD/s9q/ye3w+t5wj90Lmvobq8d0j5MTvU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bQ8mT/RfmBejZyuJu/+QtmWNzdv0tI1HBzKLV0XcwZXSHHVzEe8SiaAPArKA5Gii+Tk6bbIx+dXZTcQJmSIy5etvFk91tXvoPR4OaPW9vd0KUIo3wUtqTYEmuvxWV1so/gkGpwqolQi5dQhqV2QBZeo9RVcu+qZiUniBwPbFTAk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de; spf=pass smtp.mailfrom=pengutronix.de; arc=none smtp.client-ip=185.203.200.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pengutronix.de Received: from drehscheibe.grey.stw.pengutronix.de (drehscheibe.grey.stw.pengutronix.de [IPv6:2a0a:edc0:0:c01:1d::a2]) (Authenticated sender: relay-from-drehscheibe.grey.stw.pengutronix.de) by mx1.white.stw.pengutronix.de (Postfix) with ESMTPSA id 684EB202B60; Wed, 29 Jul 2026 12:29:26 +0200 (CEST) Received: from moin.white.stw.pengutronix.de ([2a0a:edc0:0:b01:1d::7b] helo=bjornoya.blackshift.org) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1wp1XS-001rnA-01; Wed, 29 Jul 2026 12:29:26 +0200 Received: from blackshift.org (p4ffb2dc6.dip0.t-ipconnect.de [79.251.45.198]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519MLKEM768 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) (Authenticated sender: mkl-all@blackshift.org) by smtp.blackshift.org (Postfix) with ESMTPSA id AAB1F575DBB; Wed, 29 Jul 2026 10:28:10 +0000 (UTC) From: Marc Kleine-Budde To: netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org, kernel@pengutronix.de, Tetsuo Handa , Oleksij Rempel , stable@kernel.org, Marc Kleine-Budde Subject: [PATCH net 01/20] can: j1939: use netdevice_tracker for j1939_{priv,session,ecu} tracking Date: Wed, 29 Jul 2026 12:12:41 +0200 Message-ID: <20260729102802.505168-2-mkl@pengutronix.de> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260729102802.505168-1-mkl@pengutronix.de> References: <20260729102802.505168-1-mkl@pengutronix.de> Precedence: bulk X-Mailing-List: linux-can@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Tetsuo Handa syzbot is still reporting unregister_netdevice: waiting for vcan0 to become free. Usage count = 2 problem. A debug printk() patch in linux-next-20260508 identified that there is dev_hold()/dev_put() imbalance in j1939_priv management. Call trace for vcan0[26] +4 at __dev_hold include/linux/netdevice.h:4470 [inline] netdev_hold include/linux/netdevice.h:4513 [inline] dev_hold include/linux/netdevice.h:4536 [inline] j1939_priv_create net/can/j1939/main.c:140 [inline] j1939_netdev_start+0x36b/0xc10 net/can/j1939/main.c:268 j1939_sk_bind+0x853/0xb30 net/can/j1939/socket.c:506 __sys_bind_socket net/socket.c:1948 [inline] __sys_bind+0x2e9/0x410 net/socket.c:1979 Call trace for vcan0[28] -3 at __dev_put include/linux/netdevice.h:4456 [inline] netdev_put include/linux/netdevice.h:4523 [inline] dev_put include/linux/netdevice.h:4548 [inline] __j1939_priv_release net/can/j1939/main.c:166 [inline] kref_put include/linux/kref.h:65 [inline] j1939_priv_put+0x128/0x270 net/can/j1939/main.c:172 j1939_sk_sock_destruct+0x52/0x90 net/can/j1939/socket.c:388 __sk_destruct+0x8d/0x9d0 net/core/sock.c:2352 rcu_do_batch kernel/rcu/tree.c:2617 [inline] rcu_core kernel/rcu/tree.c:2869 [inline] rcu_cpu_kthread+0x99e/0x1470 kernel/rcu/tree.c:2957 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 This refcount leak in j1939_priv might be caused by a refcount leak in j1939_{session,ecu} because j1939_{session,ecu} holds a ref on j1939_priv. For further investigation using upstream kernels, enable netdevice_tracker in j1939_{priv,session,ecu} management. Signed-off-by: Tetsuo Handa Acked-by: Oleksij Rempel Signed-off-by: Oleksij Rempel Link: https://patch.msgid.link/20260728055835.1151785-2-o.rempel@pengutronix.de Cc: stable@kernel.org Signed-off-by: Marc Kleine-Budde --- net/can/j1939/bus.c | 2 ++ net/can/j1939/j1939-priv.h | 3 +++ net/can/j1939/main.c | 8 ++++---- net/can/j1939/transport.c | 2 ++ 4 files changed, 11 insertions(+), 4 deletions(-) diff --git a/net/can/j1939/bus.c b/net/can/j1939/bus.c index dc374286eeb6..cdc3c0a71937 100644 --- a/net/can/j1939/bus.c +++ b/net/can/j1939/bus.c @@ -20,6 +20,7 @@ static void __j1939_ecu_release(struct kref *kref) struct j1939_priv *priv = ecu->priv; list_del(&ecu->list); + netdev_put(priv->ndev, &ecu->priv_dev_tracker); kfree(ecu); j1939_priv_put(priv); } @@ -155,6 +156,7 @@ struct j1939_ecu *j1939_ecu_create_locked(struct j1939_priv *priv, name_t name) if (!ecu) return ERR_PTR(-ENOMEM); kref_init(&ecu->kref); + netdev_hold(priv->ndev, &ecu->priv_dev_tracker, gfp_any()); ecu->addr = J1939_IDLE_ADDR; ecu->name = name; diff --git a/net/can/j1939/j1939-priv.h b/net/can/j1939/j1939-priv.h index 81f58924b4ac..cf26352d1d8c 100644 --- a/net/can/j1939/j1939-priv.h +++ b/net/can/j1939/j1939-priv.h @@ -38,6 +38,7 @@ struct j1939_ecu { struct hrtimer ac_timer; struct kref kref; struct j1939_priv *priv; + netdevice_tracker priv_dev_tracker; /* count users, to help transport protocol decide for interaction */ int nusers; @@ -60,6 +61,7 @@ struct j1939_priv { rwlock_t lock; struct net_device *ndev; + netdevice_tracker dev_tracker; /* list of 256 ecu ptrs, that cache the claimed addresses. * also protected by the above lock @@ -230,6 +232,7 @@ enum j1939_session_state { struct j1939_session { struct j1939_priv *priv; + netdevice_tracker priv_dev_tracker; struct list_head active_session_list_entry; struct list_head sk_session_queue_entry; struct kref kref; diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c index 9937c04241bc..5e5e6c228f22 100644 --- a/net/can/j1939/main.c +++ b/net/can/j1939/main.c @@ -137,7 +137,7 @@ static struct j1939_priv *j1939_priv_create(struct net_device *ndev) priv->ndev = ndev; kref_init(&priv->kref); kref_init(&priv->rx_kref); - dev_hold(ndev); + netdev_hold(ndev, &priv->dev_tracker, GFP_KERNEL); netdev_dbg(priv->ndev, "%s : 0x%p\n", __func__, priv); @@ -163,7 +163,7 @@ static void __j1939_priv_release(struct kref *kref) WARN_ON_ONCE(!list_empty(&priv->ecus)); WARN_ON_ONCE(!list_empty(&priv->j1939_socks)); - dev_put(ndev); + netdev_put(ndev, &priv->dev_tracker); kfree(priv); } @@ -281,7 +281,7 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev) */ kref_get(&priv_new->rx_kref); mutex_unlock(&j1939_netdev_lock); - dev_put(ndev); + netdev_put(ndev, &priv->dev_tracker); kfree(priv); return priv_new; } @@ -298,7 +298,7 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev) j1939_priv_set(ndev, NULL); mutex_unlock(&j1939_netdev_lock); - dev_put(ndev); + netdev_put(ndev, &priv->dev_tracker); kfree(priv); return ERR_PTR(ret); diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index 8a31cb23bc76..98f96362b20f 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -283,6 +283,7 @@ static void j1939_session_destroy(struct j1939_session *session) kfree_skb(skb); } __j1939_session_drop(session); + netdev_put(session->priv->ndev, &session->priv_dev_tracker); j1939_priv_put(session->priv); kfree(session); } @@ -1526,6 +1527,7 @@ static struct j1939_session *j1939_session_new(struct j1939_priv *priv, INIT_LIST_HEAD(&session->active_session_list_entry); INIT_LIST_HEAD(&session->sk_session_queue_entry); kref_init(&session->kref); + netdev_hold(priv->ndev, &session->priv_dev_tracker, gfp_any()); j1939_priv_get(priv); session->priv = priv; base-commit: 3bd438a58e910db5dc369aa25dfed1fc95f1b596 -- 2.53.0