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From: Marco Elver <elver@google.com>
To: Andrea Righi <andrea.righi@canonical.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Alexander Potapenko <glider@google.com>,
	kasan-dev@googlegroups.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: BUG: soft lockup in __kmalloc_node() with KFENCE enabled
Date: Wed, 20 Oct 2021 08:00:00 +0200	[thread overview]
Message-ID: <CANpmjNMXNZX5QyLhXtT87ycnAhEe1upU_cL9D3+NOGKEn-gtCw@mail.gmail.com> (raw)
In-Reply-To: <YWRNVTk9N8K0RMst@arighi-desktop>

On Mon, 11 Oct 2021 at 16:42, Andrea Righi <andrea.righi@canonical.com> wrote:
> On Mon, Oct 11, 2021 at 12:03:52PM +0200, Marco Elver wrote:
> > On Mon, 11 Oct 2021 at 11:53, Andrea Righi <andrea.righi@canonical.com> wrote:
> > > On Mon, Oct 11, 2021 at 11:23:32AM +0200, Andrea Righi wrote:
> > > ...
> > > > > You seem to use the default 20s stall timeout. FWIW syzbot uses 160
> > > > > secs timeout for TCG emulation to avoid false positive warnings:
> > > > > https://github.com/google/syzkaller/blob/838e7e2cd9228583ca33c49a39aea4d863d3e36d/dashboard/config/linux/upstream-arm64-kasan.config#L509
> > > > > There are a number of other timeouts raised as well, some as high as
> > > > > 420 seconds.
> > > >
> > > > I see, I'll try with these settings and see if I can still hit the soft
> > > > lockup messages.
> > >
> > > Still getting soft lockup messages even with the new timeout settings:
> > >
> > > [  462.663766] watchdog: BUG: soft lockup - CPU#2 stuck for 430s! [systemd-udevd:168]
> > > [  462.755758] watchdog: BUG: soft lockup - CPU#3 stuck for 430s! [systemd-udevd:171]
> > > [  924.663765] watchdog: BUG: soft lockup - CPU#2 stuck for 861s! [systemd-udevd:168]
> > > [  924.755767] watchdog: BUG: soft lockup - CPU#3 stuck for 861s! [systemd-udevd:171]
> >
> > The lockups are expected if you're hitting the TCG bug I linked. Try
> > to pass '-enable-kvm' to the inner qemu instance (my bad if you
> > already have), assuming that's somehow easy to do.
>
> If I add '-enable-kvm' I can triggering other random panics (almost
> immediately), like this one for example:

Just FYI: https://lkml.kernel.org/r/20211019102524.2807208-2-elver@google.com

But you can already flip that switch in your config
(CONFIG_KFENCE_STATIC_KEYS=n), which we recommend as a default now.

As a side-effect it'd also make your QEMU TCG tests pass.

  parent reply	other threads:[~2021-10-20  6:01 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-10 13:53 BUG: soft lockup in __kmalloc_node() with KFENCE enabled Andrea Righi
2021-10-11  6:00 ` Marco Elver
2021-10-11  6:32   ` Andrea Righi
2021-10-11  6:48     ` Marco Elver
2021-10-11  7:10       ` Andrea Righi
2021-10-11  7:19         ` Dmitry Vyukov
2021-10-11  9:23           ` Andrea Righi
2021-10-11  9:52             ` Andrea Righi
2021-10-11 10:03               ` Marco Elver
2021-10-11 14:42                 ` Andrea Righi
2021-10-11 15:00                   ` Dmitry Vyukov
2021-10-11 15:11                     ` Andrea Righi
2021-10-11 15:16                       ` Dmitry Vyukov
2021-10-20  6:00                   ` Marco Elver [this message]
2021-10-20  6:11                     ` Andrea Righi

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