From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.tipi-net.de (mail.tipi-net.de [194.13.80.246]) (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 BA7C6491B12; Mon, 19 Oct 2026 14:42:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.13.80.246 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792420930; cv=none; b=sK/FO4Ix6Hb9TCfe0ddqrynXFV7UzF0jZuhKWqJoh/w3yfHkxTP/sbaEJFFTSoDO2aoH9zKZ3lyNRay2F7AgELFB449lgtkD27bUNeXtHO3pIiSfqpgx/VbO6f+jMZpzI/wyBV6eQVC6R2KReclpeRtQufb80SP/H5a6TWyRvL4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792420930; c=relaxed/simple; bh=+CcE//8LwHV5giiOzprhXnBLjNfbqHe6aALXRB3Ow80=; h=MIME-Version:Date:From:To:Cc:Subject:In-Reply-To:References: Message-ID:Content-Type; b=oZpm9DMUNqO38jmObRi41HdToJlxjB6rAl/cMTLbf5MLAxifPq7MWeeQXFI4bAgs2bPinU9WX+/96O2laSBB1ETlv0ZJIM+Z/JespVFNQpn/tSQa9UwWF/eOWx5NH6oWJpcvpmRn+PfEIuwQxIN7t/7e+B/eFFIuj5zcfMS7mRI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=tipi-net.de; spf=pass smtp.mailfrom=tipi-net.de; dkim=pass (2048-bit key) header.d=tipi-net.de header.i=@tipi-net.de header.b=n8aGCNXm; arc=none smtp.client-ip=194.13.80.246 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=tipi-net.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=tipi-net.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=tipi-net.de header.i=@tipi-net.de header.b="n8aGCNXm" Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 354A4A156A; Mon, 19 Oct 2026 16:42:02 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tipi-net.de; s=dkim; t=1792420922; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=gdPAFwtkiyGOrrmpDJKuYvH8c98AWepp1hYqr6NQ5+A=; b=n8aGCNXms/uv7CzfapYewb+6FNb5I6XxvEM2THqbJ+0eVNxdgBR1CdLKSwAiP6yTZtl/+T BiQqHZgfXpvS/NVyOU+x9fYvXTl8J12rfCsyzJmNMvgf2INH5/p1d/4S6eYV3h2jcQEj9l o+84ZZILEiA1SxvgRTuXJUt2fvcPfJClCXVIpnSDaZHosUzqijz3rUU12HJui/Fsu0yAXN 7jzCW2uzfRSZCfzjayRdU41IZp0mee9yAWAwg4xw6oOzsA5Lui9jZFpYEJXTTSYPv7P/Qm 6BLxQydaKShJXXDOQt3fMgc/1q/5/coEb+FuAJ4cbj0GsgOqc0ysVXApbKaD5A== Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Mon, 19 Oct 2026 16:42:02 +0200 From: Nicolai Buchwitz To: Mikkel Eskildsen Cc: Oliver Neukum , Breno Leitao , netdev@vger.kernel.org, linux-usb@vger.kernel.org, Jakub Kicinski , Eric Dumazet , Paolo Abeni Subject: Re: [BUG] cdc_ncm: soft lockup with netconsole over an AX88179B dock In-Reply-To: References: Message-ID: <6aaea20ede0bd16a5138bc126f3ec897@tipi-net.de> X-Sender: nb@tipi-net.de Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-Last-TLS-Session-Version: TLSv1.3 Hi Mikkel On 19.10.2026 15:48, Mikkel Eskildsen wrote: > Hi, > > My laptop panicked with a soft lockup on 2026-10-16 and again on > 2026-10-19 while netconsole was running over a USB dock NIC that uses > cdc_ncm. Both times the laptop was docked and netconsole was on that > interface. I have turned netconsole off for now. I was able to reproduce the issue with a similar device. Seems like netconsole holds the tx lock while the cdc_ncm driver lets pending network work run in the middle of the send. ... which then starves on the lock netconsole still holds. Below is a patch which hopefully fixes the issue. > > The trace below is from pstore. The netconsole thread on CPU15 is in > netpoll_send_skb -> usbnet_start_xmit -> cdc_ncm_tx_fixup. The > spin_unlock_bh() in cdc_ncm_tx_fixup runs pending softirqs, TCP RX > sends a packet and it spins in sch_direct_xmit. My guess is that it > waits for the eth0 tx queue lock that netpoll already holds. The other > CPUs then wait on the socket lock until the watchdog panics. > > The first panic looks the same, but pstore lost the part with the > netconsole thread. > > [...] > I can test a patch if that helps. Is this a known issue? https://github.com/nbuchwitz/linux/commit/319cb0933e2eaf984b98906ebddb55befb4e2996 > > Mikkel