From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EBC2C388F7 for ; Thu, 29 Oct 2020 02:00:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA54D2076B for ; Thu, 29 Oct 2020 02:00:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=akamai.com header.i=@akamai.com header.b="o1gULdxa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728969AbgJ2CA2 (ORCPT ); Wed, 28 Oct 2020 22:00:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728194AbgJ1Vvk (ORCPT ); Wed, 28 Oct 2020 17:51:40 -0400 Received: from mx0b-00190b01.pphosted.com (mx0b-00190b01.pphosted.com [IPv6:2620:100:9005:57f::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74D11C0613CF; Wed, 28 Oct 2020 14:51:40 -0700 (PDT) Received: from pps.filterd (m0050102.ppops.net [127.0.0.1]) by m0050102.ppops.net-00190b01. (8.16.0.42/8.16.0.42) with SMTP id 09SJG5dG030030; Wed, 28 Oct 2020 20:04:54 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=akamai.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=jan2016.eng; bh=nXQOVbyB8pxdeSVRR03uPD+fV/eyzypMF/2fEjqk2jY=; b=o1gULdxacjs1WySERaLK/PEwjzLxGW55S51Mz4/IVbBOqwiHlS17LQNkyewF6tY4dvAU UREYeszxKOqZEM2p/MZ39L9vFCP8G951nbSDiswb7kb5tx0YrkdKiHGOG4bTGhAWZovW IS5N/fNyT5X0flLLAJADzBAu91zBqcb3HoHlkd86zEfIJs/Kg7kNqOz2F07SyrsYlHUb zb+4wJYHUNiIMxIYS1b9G9dJPR0cUTN79N+WbJ2ED1FES8S2UM2gcnX1rs7UkXgPueC/ xkcT/1BrAudCSL3wBI2J5CjBqhGKjK1KYpTTNEKBYE30MVyaWR/YGbuAMcw3yO9yeQOB zg== Received: from prod-mail-ppoint5 (prod-mail-ppoint5.akamai.com [184.51.33.60] (may be forged)) by m0050102.ppops.net-00190b01. with ESMTP id 34ccex7qe7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 28 Oct 2020 20:04:53 +0000 Received: from pps.filterd (prod-mail-ppoint5.akamai.com [127.0.0.1]) by prod-mail-ppoint5.akamai.com (8.16.0.42/8.16.0.42) with SMTP id 09SJJk3H021466; Wed, 28 Oct 2020 13:04:53 -0700 Received: from prod-mail-relay11.akamai.com ([172.27.118.250]) by prod-mail-ppoint5.akamai.com with ESMTP id 34f1pyhbsn-1; Wed, 28 Oct 2020 13:04:53 -0700 Received: from [0.0.0.0] (prod-ssh-gw01.bos01.corp.akamai.com [172.27.119.138]) by prod-mail-relay11.akamai.com (Postfix) with ESMTP id C90E923A52; Wed, 28 Oct 2020 20:04:52 +0000 (GMT) Subject: Re: [PATCH v2 net] net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc To: Cong Wang Cc: Yunsheng Lin , "Hunt, Joshua" , Jamal Hadi Salim , Jiri Pirko , David Miller , Jakub Kicinski , Linux Kernel Network Developers , LKML , "linuxarm@huawei.com" , John Fastabend , Eric Dumazet References: <1599562954-87257-1-git-send-email-linyunsheng@huawei.com> <830f85b5-ef29-c68e-c982-de20ac880bd9@huawei.com> From: Vishwanath Pai Message-ID: <19f888c2-8bc1-ea56-6e19-4cb4841c4da0@akamai.com> Date: Wed, 28 Oct 2020 16:04:52 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-10-28_09:2020-10-28,2020-10-28 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 suspectscore=0 malwarescore=0 mlxscore=0 bulkscore=0 mlxlogscore=999 spamscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010280122 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-10-28_09:2020-10-28,2020-10-28 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 lowpriorityscore=0 bulkscore=0 clxscore=1015 adultscore=0 malwarescore=0 phishscore=0 mlxlogscore=999 impostorscore=0 suspectscore=0 priorityscore=1501 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010280122 X-Agari-Authentication-Results: mx.akamai.com; spf=${SPFResult} (sender IP is 184.51.33.60) smtp.mailfrom=vpai@akamai.com smtp.helo=prod-mail-ppoint5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/28/20 1:47 PM, Cong Wang wrote: > On Wed, Oct 28, 2020 at 8:37 AM Pai, Vishwanath wrote: >> Hi, >> >> We noticed some problems when testing the latest 5.4 LTS kernel and traced it >> back to this commit using git bisect. When running our tests the machine stops >> responding to all traffic and the only way to recover is a reboot. I do not see >> a stack trace on the console. > > Do you mean the machine is still running fine just the network is down? > > If so, can you dump your tc config with stats when the problem is happening? > (You can use `tc -s -d qd show ...`.) > >> >> This can be reproduced using the packetdrill test below, it should be run a >> few times or in a loop. You should hit this issue within a few tries but >> sometimes might take up to 15-20 tries. > ... >> I can reproduce the issue easily on v5.4.68, and after reverting this commit it >> does not happen anymore. > > This is odd. The patch in this thread touches netdev reset path, if packetdrill > is the only thing you use to trigger the bug (that is netdev is always active), > I can not connect them. > > Thanks. Hi Cong, > Do you mean the machine is still running fine just the network is down? I was able to access the machine via serial console, it looks like it is up and running, just that networking is down. > If so, can you dump your tc config with stats when the problem is happening? > (You can use `tc -s -d qd show ...`.) If I try running tc when the machine is in this state the command never returns. It doesn't print anything but doesn't exit either. > This is odd. The patch in this thread touches netdev reset path, if packetdrill > is the only thing you use to trigger the bug (that is netdev is always active), > I can not connect them. I think packetdrill creates a tun0 interface when it starts the test and tears it down at the end, so it might be hitting this code path during teardown. P.S: My mail server is having connectivity issues with vger.kernel.org so messages aren't getting delivered to netdev. It'll hopefully get resolved soon. Thanks, Vishwanath