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 880C8154BE0; Mon, 10 Mar 2025 17:46:29 +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=1741628789; cv=none; b=NcplJWOgp1Vs6idwq9YsjRVTEBq8SURd5XmPs7HZ9jaY00H/09UIFsMidVmGDXgfuPijhkvHsmpYJIj7Cqx4/p/kgkswWfJqRPYlie8rmnUIBGBLgOLNmNXwI8+A82HjyDcPiluf755k/0vQfB8nxBlOk1qDqonAB/jgdN/nYJw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741628789; c=relaxed/simple; bh=bJM08IPsLUnQtXuzZB47QJo6UA5BQymbOIazH930n9Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=u2UK9DMBTs5VBkWBBK8UiRCk1xAL74D/VfoJViPD6N1qnhjODAKyHk6ofazV6MtA5ZXgX9/71tQbYAHB2GzJ3mH7KoM5qrrmpDB43QI2vqs07S9s6xmL2ut6rWCrWK2+yG7FlRsDUSg8y0ugf5p7a3cvnQYPQYU29p1fEPn/XG0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pOarwf1g; 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="pOarwf1g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1216DC4CEE5; Mon, 10 Mar 2025 17:46:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741628789; bh=bJM08IPsLUnQtXuzZB47QJo6UA5BQymbOIazH930n9Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pOarwf1gDe0Dt43zQpYYhZoQZRYFq1jZUG3N7fIGKTr4r397B4979XDJkfCtJkrfB fALH7HPuYcW+t2rad2Q/wGJtIoIR/y7w0d4eieaSO2obpMxOBhGQF9kKFmmLOSN5Ge K/25hF6rI5v5kZ772Eljzr/9ggNgmmQ+mRciNtCA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Liu Jian , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 069/620] net: let net.core.dev_weight always be non-zero Date: Mon, 10 Mar 2025 17:58:35 +0100 Message-ID: <20250310170548.303463744@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250310170545.553361750@linuxfoundation.org> References: <20250310170545.553361750@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Liu Jian [ Upstream commit d1f9f79fa2af8e3b45cffdeef66e05833480148a ] The following problem was encountered during stability test: (NULL net_device): NAPI poll function process_backlog+0x0/0x530 \ returned 1, exceeding its budget of 0. ------------[ cut here ]------------ list_add double add: new=ffff88905f746f48, prev=ffff88905f746f48, \ next=ffff88905f746e40. WARNING: CPU: 18 PID: 5462 at lib/list_debug.c:35 \ __list_add_valid_or_report+0xf3/0x130 CPU: 18 UID: 0 PID: 5462 Comm: ping Kdump: loaded Not tainted 6.13.0-rc7+ RIP: 0010:__list_add_valid_or_report+0xf3/0x130 Call Trace: ? __warn+0xcd/0x250 ? __list_add_valid_or_report+0xf3/0x130 enqueue_to_backlog+0x923/0x1070 netif_rx_internal+0x92/0x2b0 __netif_rx+0x15/0x170 loopback_xmit+0x2ef/0x450 dev_hard_start_xmit+0x103/0x490 __dev_queue_xmit+0xeac/0x1950 ip_finish_output2+0x6cc/0x1620 ip_output+0x161/0x270 ip_push_pending_frames+0x155/0x1a0 raw_sendmsg+0xe13/0x1550 __sys_sendto+0x3bf/0x4e0 __x64_sys_sendto+0xdc/0x1b0 do_syscall_64+0x5b/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e The reproduction command is as follows: sysctl -w net.core.dev_weight=0 ping 127.0.0.1 This is because when the napi's weight is set to 0, process_backlog() may return 0 and clear the NAPI_STATE_SCHED bit of napi->state, causing this napi to be re-polled in net_rx_action() until __do_softirq() times out. Since the NAPI_STATE_SCHED bit has been cleared, napi_schedule_rps() can be retriggered in enqueue_to_backlog(), causing this issue. Making the napi's weight always non-zero solves this problem. Triggering this issue requires system-wide admin (setting is not namespaced). Fixes: e38766054509 ("[NET]: Fix sysctl net.core.dev_weight") Fixes: 3d48b53fb2ae ("net: dev_weight: TX/RX orthogonality") Signed-off-by: Liu Jian Link: https://patch.msgid.link/20250116143053.4146855-1-liujian56@huawei.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/sysctl_net_core.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index ed20cbdd19315..60ea97aaea7d9 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -240,7 +240,7 @@ static int proc_do_dev_weight(struct ctl_table *table, int write, int ret, weight; mutex_lock(&dev_weight_mutex); - ret = proc_dointvec(table, write, buffer, lenp, ppos); + ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (!ret && write) { weight = READ_ONCE(weight_p); WRITE_ONCE(dev_rx_weight, weight * dev_weight_rx_bias); @@ -351,6 +351,7 @@ static struct ctl_table net_core_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_do_dev_weight, + .extra1 = SYSCTL_ONE, }, { .procname = "dev_weight_rx_bias", @@ -358,6 +359,7 @@ static struct ctl_table net_core_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_do_dev_weight, + .extra1 = SYSCTL_ONE, }, { .procname = "dev_weight_tx_bias", @@ -365,6 +367,7 @@ static struct ctl_table net_core_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_do_dev_weight, + .extra1 = SYSCTL_ONE, }, { .procname = "netdev_max_backlog", -- 2.39.5