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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 1DF9CC43381 for ; Tue, 26 Mar 2019 10:17:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EB57620856 for ; Tue, 26 Mar 2019 10:17:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731408AbfCZKRd (ORCPT ); Tue, 26 Mar 2019 06:17:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60614 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726248AbfCZKRd (ORCPT ); Tue, 26 Mar 2019 06:17:33 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1A449C057F3D; Tue, 26 Mar 2019 10:17:33 +0000 (UTC) Received: from [10.72.12.211] (ovpn-12-211.pek2.redhat.com [10.72.12.211]) by smtp.corp.redhat.com (Postfix) with ESMTP id D134F48D24; Tue, 26 Mar 2019 10:17:27 +0000 (UTC) Subject: Re: INFO: task hung in vhost_net_stop_vq To: "Michael S. Tsirkin" , syzbot Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, virtualization@lists.linux-foundation.org, weiyj.lk@gmail.com References: <0000000000004f8499057be95e1d@google.com> <0000000000008ee87005847fc985@google.com> <20190325100223-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: Date: Tue, 26 Mar 2019 18:17:26 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190325100223-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 26 Mar 2019 10:17:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/3/25 下午10:02, Michael S. Tsirkin wrote: > Looks like more iotlb locking mess? Looking at the calltrace: [ 221.743675] ============================================= [ 221.744297] [ INFO: possible recursive locking detected ] [ 221.744944] 4.7.0+ #1 Not tainted [ 221.745326] --------------------------------------------- [ 221.746128] syz-executor1/6823 is trying to acquire lock: [ 221.746737] (&vq->mutex){+.+...}, at: [] vhost_process_iotlb_msg+0xe0/0x9e0 [ 221.747789] [ 221.747789] but task is already holding lock: [ 221.748470] (&vq->mutex){+.+...}, at: [] vhost_process_iotlb_msg+0xe0/0x9e0 [ 221.749535] [ 221.749535] other info that might help us debug this: [ 221.750280] Possible unsafe locking scenario: [ 221.750280] [ 221.750946] CPU0 [ 221.751232] ---- [ 221.751523] lock(&vq->mutex); [ 221.751922] lock(&vq->mutex); [ 221.752339] [ 221.752339] *** DEADLOCK *** [ 221.752339] I could not think of a path that can hit this. And I could not reproduce with the reproducer in the link in net-next. Thanks > > On Tue, Mar 19, 2019 at 10:21:00PM -0700, syzbot wrote: >> syzbot has bisected this bug to: >> >> commit 6b1e6cc7855b09a0a9bfa1d9f30172ba366f161c >> Author: Jason Wang >> Date: Thu Jun 23 06:04:32 2016 +0000 >> >> vhost: new device IOTLB API >> >> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1486ad27200000 >> start commit: 6b1e6cc7 vhost: new device IOTLB API >> git tree: upstream >> final crash: https://syzkaller.appspot.com/x/report.txt?x=1686ad27200000 >> console output: https://syzkaller.appspot.com/x/log.txt?x=1286ad27200000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=c94f9f0c0363db4b >> dashboard link: https://syzkaller.appspot.com/bug?extid=d21e6e297322a900c128 >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=141db34d400000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=108ef293400000 >> >> Reported-by: syzbot+d21e6e297322a900c128@syzkaller.appspotmail.com >> Fixes: 6b1e6cc7 ("vhost: new device IOTLB API")