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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Fri, 13 Mar 2020 08:43:15 +0100
Message-ID: <CACT4Y+bCat++Gc5H2JYjsQQ2hzQyEa3H-VKmb93H7tLrTVS31A@mail.gmail.com>
Subject: Re: unexpected kernel reboot (3)
To:     Jim Mattson <jmattson@google.com>
Cc:     syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        LKML <linux-kernel@vger.kernel.org>,
        syzbot <syzbot+cce9ef2dd25246f815ee@syzkaller.appspotmail.com>
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On Thu, Mar 12, 2020 at 9:36 PM Jim Mattson <jmattson@google.com> wrote:
>
> On Wed, Mar 11, 2020 at 1:35 PM Jim Mattson <jmattson@google.com> wrote:
> >
> > On Wed, Mar 11, 2020 at 1:18 PM Dmitry Vyukov <dvyukov@google.com> wrote:
> >
> > > This happened 10K+ times.
> > > If GCE VM is rebooted by doing something with KVM subsystem, I assume
> > > it's a GCE bug (?). +Jim
> >
> > The L1 guest may have done something that's unsupported, or it may
> > just be a bug in the L0 hypervisor.
>
> I can't reproduce this in GCE with the collateral provided.

As far as I understand, this may depend on GCE host kernel and/or host
CPU, right? Do we have an ability to unit test on all combinations?
Looking at the rate and reproducers on the dashboard I see interesting
patterns. Perhaps the best time to try to reproduce is these periods
when syzbot comes up with lots of reproducers. But it's not now...