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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 9007EC433E2 for ; Wed, 9 Sep 2020 21:54:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61FB721D81 for ; Wed, 9 Sep 2020 21:54:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728611AbgIIVyk (ORCPT ); Wed, 9 Sep 2020 17:54:40 -0400 Received: from mga09.intel.com ([134.134.136.24]:11808 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726226AbgIIVyk (ORCPT ); Wed, 9 Sep 2020 17:54:40 -0400 IronPort-SDR: PlTa6i5k8wWbfvqthBpLumDhZ1w+xvpXM2hlvzFgQyNOJotzf/z55V0Mn+ILxs2WMrUfDH5jIW pqPPJFEm7EpQ== X-IronPort-AV: E=McAfee;i="6000,8403,9739"; a="159379825" X-IronPort-AV: E=Sophos;i="5.76,410,1592895600"; d="scan'208";a="159379825" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Sep 2020 14:54:39 -0700 IronPort-SDR: xEQVTvgSU7FZDwgkn9J49hOcTAsQJFTQq757N5+2SSN3hyhLWp5jR4mvDVc3QHwhJOfpRYDt5Z +fn0mRtQY4iw== X-IronPort-AV: E=Sophos;i="5.76,410,1592895600"; d="scan'208";a="449356036" Received: from rbentz-mobl.amr.corp.intel.com (HELO ellie) ([10.212.86.17]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Sep 2020 14:54:38 -0700 From: Vinicius Costa Gomes To: Jakub Kicinski , syzbot Cc: davem@davemloft.net, jhs@mojatatu.com, jiri@resnulli.us, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, xiyou.wangcong@gmail.com Subject: Re: INFO: rcu detected stall in cleanup_net (4) In-Reply-To: <20200909085203.5e335c61@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> References: <000000000000db78de05aedabb5a@google.com> <20200909085203.5e335c61@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Date: Wed, 09 Sep 2020 14:54:36 -0700 Message-ID: <877dt2pqeb.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Jakub, Jakub Kicinski writes: > On Tue, 08 Sep 2020 22:29:21 -0700 syzbot wrote: >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: 59126901 Merge tag 'perf-tools-fixes-for-v5.9-2020-09-03' .. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=12edb935900000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=3c5f6ce8d5b68299 >> dashboard link: https://syzkaller.appspot.com/bug?extid=8267241609ae8c23b248 >> compiler: gcc (GCC) 10.1.0-syz 20200507 >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157c7aa5900000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13c92ef9900000 >> >> The issue was bisected to: >> >> commit 5a781ccbd19e4664babcbe4b4ead7aa2b9283d22 >> Author: Vinicius Costa Gomes >> Date: Sat Sep 29 00:59:43 2018 +0000 >> >> tc: Add support for configuring the taprio scheduler > > > Vinicius, could you please take a look at all the syzbot reports which > point to your commit? I know syzbot bisection is not super reliable, > but at least 3 reports point to your commit now, so something's > probably going on. I did take a look, and it seems that it all boils down to having too small (unreasonable?) intervals in the schedule, which causes the hrtimer handler to starve the other kernel threads. I have a quick fix to restrict the interval values to more sensible values (at least equal to the time it takes to transmit the mininum ethernet frame size), I am testing it and I will propose it soon. But a proper solution will require more time. Cheers, -- Vinicius