From: Ingo Molnar <mingo@kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Gilbert <benjamin.gilbert@coreos.com>,
x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
stable@vger.kernel.org
Subject: Re: "bad pmd" errors + oops with KPTI on 4.14.11 after loading X.509 certs
Date: Wed, 3 Jan 2018 16:48:33 +0100 [thread overview]
Message-ID: <20180103154833.fhkbwonz6zhm26ax@gmail.com> (raw)
In-Reply-To: <20180103092016.GA23772@kroah.com>
* Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> On Wed, Jan 03, 2018 at 12:46:00AM -0800, Benjamin Gilbert wrote:
> > [resending with less web]
>
> (adding lkml and x86 developers)
>
> > Hi all,
> >
> > In our regression tests on kernel 4.14.11, we're occasionally seeing a run
> > of "bad pmd" messages during boot, followed by a "BUG: unable to handle
> > kernel paging request". This happens on no more than a couple percent of
> > boots, but we've seen it on AWS HVM, GCE, Oracle Cloud VMs, and local QEMU
> > instances. It always happens immediately after "Loading compiled-in X.509
> > certificates". I can't reproduce it on 4.14.10, nor, so far, on 4.14.11
> > with pti=off. Here's a sample backtrace:
A few other things to check:
first please test the latest WIP.x86/pti branch which has a couple of fixes.
In a -stable kernel tree you should be able to do:
git pull --no-tags git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.x86/pti
in particular this recent fix from a couple of hours ago might make a difference:
52994c256df3: x86/pti: Make sure the user/kernel PTEs match
Note that this commit:
694d99d40972: x86/cpu, x86/pti: Do not enable PTI on AMD processors
disables PTI on AMD CPUs - so if you'd like to test it more broadly on all CPUs
then you'll need to add "pti=on" to your boot commandline.
Thanks,
Ingo
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next prev parent reply other threads:[~2018-01-03 15:48 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-03 8:36 "bad pmd" errors + oops with KPTI on 4.14.11 after loading X.509 certs Benjamin Gilbert
2018-01-03 8:46 ` Benjamin Gilbert
2018-01-03 9:20 ` Greg Kroah-Hartman
2018-01-03 15:48 ` Ingo Molnar [this message]
2018-01-03 22:32 ` Benjamin Gilbert
2018-01-03 22:34 ` Thomas Gleixner
2018-01-03 22:49 ` Benjamin Gilbert
2018-01-03 22:57 ` Thomas Gleixner
2018-01-03 22:58 ` Thomas Gleixner
2018-01-03 23:44 ` Andy Lutomirski
2018-01-03 23:46 ` Thomas Gleixner
2018-01-04 0:27 ` Andy Lutomirski
2018-01-04 0:38 ` Benjamin Gilbert
2018-01-04 0:33 ` Benjamin Gilbert
2018-01-04 0:37 ` Thomas Gleixner
2018-01-04 7:14 ` Ingo Molnar
2018-01-04 7:18 ` Greg Kroah-Hartman
2018-01-04 7:20 ` Ingo Molnar
2018-01-04 8:03 ` Greg Kroah-Hartman
2018-01-04 7:22 ` Ingo Molnar
2018-01-04 0:37 ` Andy Lutomirski
2018-01-04 4:35 ` Benjamin Gilbert
2018-01-04 4:45 ` Andy Lutomirski
2018-01-04 12:28 ` Thomas Gleixner
2018-01-04 16:17 ` Andy Lutomirski
2018-01-04 16:34 ` Thomas Gleixner
2018-01-04 19:38 ` Benjamin Gilbert
2018-01-04 1:37 ` Benjamin Gilbert
2018-01-04 4:36 ` Benjamin Gilbert
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