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=-0.8 required=3.0 tests=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 0E1EEC7618B for ; Sun, 28 Jul 2019 08:36:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE82221655 for ; Sun, 28 Jul 2019 08:36:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725965AbfG1Igs (ORCPT ); Sun, 28 Jul 2019 04:36:48 -0400 Received: from mail-io1-f67.google.com ([209.85.166.67]:44476 "EHLO mail-io1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725938AbfG1Igs (ORCPT ); Sun, 28 Jul 2019 04:36:48 -0400 Received: by mail-io1-f67.google.com with SMTP id s7so113441705iob.11 for ; Sun, 28 Jul 2019 01:36:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=JmcimYJf+Bna2bF5oHtnyvYwQab4h3brdRl3y+Yku3w=; b=ttxgB4ofvpQvE85xUj9OqhKE9qmD0ZfU3tKaOVIldjCDnP9VWW33g1DRx9t6/e5AtI /KytNr2d+W4GSHKB2F9qLkQI50xQC1eqZbM8o87yO/tIW0GRwCowOtgvSbS5bVaDlMRx ankuudOsKhAS6DhYsbGyQAR7SHyiAFplpaS53Ao74IujX7PUNeO/xqTgmK2Rn+XKKMgm eM/X5duZGN+baL3/41dPHF+KWd/FLvg7Z+MAaEhuEc6vk9HV3SJQ9j1f4oZNZqyRsrhg uEJuW2OnmO08GfOeYA0wBoQgiV+1An8psmexKbKoCPxTCzdbMw0pkCJ9xZkRXcZJfUEZ MNmQ== X-Gm-Message-State: APjAAAVisQJgBjD9o9vDxXzyB545Sctllc8vsm/jAbH9i7GPnZAxm7t0 9RvpQDpdr6CoHxLPrVTZFblLug== X-Google-Smtp-Source: APXvYqyHU6qTV7uMr9tjpRxhhvTuO4lK+5tp+FQOjsGxN+s/1qcSKnN7S1nMevwymEewifIu5iF5Gg== X-Received: by 2002:a02:b883:: with SMTP id p3mr34245354jam.79.1564303007037; Sun, 28 Jul 2019 01:36:47 -0700 (PDT) Received: from redhat.com (bzq-79-181-91-42.red.bezeqint.net. [79.181.91.42]) by smtp.gmail.com with ESMTPSA id o7sm48957845ioo.81.2019.07.28.01.36.42 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Sun, 28 Jul 2019 01:36:45 -0700 (PDT) Date: Sun, 28 Jul 2019 04:36:39 -0400 From: "Michael S. Tsirkin" To: Hillf Danton Cc: syzbot , jasowang@redhat.com, kvm@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, michal.lkml@markovi.net, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, torvalds@linux-foundation.org, virtualization@lists.linux-foundation.org, yamada.masahiro@socionext.com Subject: Re: INFO: rcu detected stall in vhost_worker Message-ID: <20190728043619-mutt-send-email-mst@kernel.org> References: <000000000000b4358f058e924c6d@google.com> <000000000000e87d14058e9728d7@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <000000000000e87d14058e9728d7@google.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Sat, Jul 27, 2019 at 04:23:23PM +0800, Hillf Danton wrote: > > Fri, 26 Jul 2019 08:26:01 -0700 (PDT) > > syzbot has bisected this bug to: > > > > commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 > > Author: Linus Torvalds > > Date: Sun Jul 7 22:41:56 2019 +0000 > > > > Linux 5.2 > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=118810bfa00000 > > start commit: 13bf6d6a Add linux-next specific files for 20190725 > > git tree: linux-next > > kernel config: https://syzkaller.appspot.com/x/.config?x=8ae987d803395886 > > dashboard link: https://syzkaller.appspot.com/bug?extid=36e93b425cd6eb54fcc1 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15112f3fa00000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=131ab578600000 > > > > Reported-by: syzbot+36e93b425cd6eb54fcc1@syzkaller.appspotmail.com > > Fixes: 0ecfebd2b524 ("Linux 5.2") > > > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -787,7 +787,6 @@ static void vhost_setup_uaddr(struct vho > size_t size, bool write) > { > struct vhost_uaddr *addr = &vq->uaddrs[index]; > - spin_lock(&vq->mmu_lock); > > addr->uaddr = uaddr; > addr->size = size; > @@ -797,7 +796,10 @@ static void vhost_setup_uaddr(struct vho > static void vhost_setup_vq_uaddr(struct vhost_virtqueue *vq) > { > spin_lock(&vq->mmu_lock); > - > + /* > + * deadlock if managing to take mmu_lock again while > + * setting up uaddr > + */ > vhost_setup_uaddr(vq, VHOST_ADDR_DESC, > (unsigned long)vq->desc, > vhost_get_desc_size(vq, vq->num), > -- Thanks! I reverted this whole commit. -- MST