Thanks!

I have tested this kernel; it doesn't work, so the problem is between
fc8704280f2ada9f61f08a2d5adc0dab169cc207 and
8eca6add0defde203282476d7969a7c13bbd7d91.

I've gotten set up with a kernel build environment; I think I can
finish the git bisect myself, but looking at the commits in that
range, I have no hope of actually fixing the underlying bug myself.
I'm building 3f6a3b035f91a22c0d3bd27630bf61eac9c8cf6c now.

On Tue, Jul 17, 2018 at 11:24 AM, Joseph Salisbury
<email address hidden> wrote:
> I built the next test kernel, up to the following commit:
> fc8704280f2ada9f61f08a2d5adc0dab169cc207
>
> The test kernel can be downloaded from:
> http://kernel.ubuntu.com/~jsalisbury/lp1777338
>
> Can you test that kernel and report back if it has the bug or not? I
> will build the next test kernel based on your test results.
>
> Thanks in advance
>
>
> MD5SUM of files:
> d76993d34e1203375090a47c4de8ebfe  linux-image-unsigned-4.15.0-23-generic_4.15.0-23.26~lp1777338Commitfc8704280f_amd64.deb
>
> 5b89b2341b858bbe2bcae88e3efaf8c8  linux-
> modules-4.15.0-23-generic_4.15.0-23.26~lp1777338Commitfc8704280f_amd64.deb
>
> 6928b4ad5f2a861ad674ff88a4745471  linux-modules-
> extra-4.15.0-23-generic_4.15.0-23.26~lp1777338Commitfc8704280f_amd64.deb
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1777338
>
> Title:
>   Linux 4.15.0-23 crashes during the boot process with a "Unable to
>   handle kernel NULL pointer dereference" message
>
> Status in linux package in Ubuntu:
>   In Progress
> Status in linux source package in Bionic:
>   In Progress
>
> Bug description:
>   I went to boot my computer today and it wouldn't boot.
>
>   I get an "Unable to handle kernel NULL pointer dereference" message
>   during the boot process, and, a bit after that, a message from the
>   kernel watchdog about CPU #0 being stuck. Then the boot process stops
>   completely.
>
>   I was able to boot the system by telling Grub to load 4.15.0-22, which
>   works perfectly fine, so there has been a regression.
>
>   I am running Ubuntu as a Xen dom0, if that matters. I haven't tried
>   booting the offending kernel version without Xen.
>
>   I'm not sure where, if anywhere, these messages go on disk, for
>   posting.
>
>   ProblemType: Bug
>   DistroRelease: Ubuntu 18.04
>   Package: linux-image-4.15.0-23-generic 4.15.0-23.25
>   ProcVersionSignature: Ubuntu 4.15.0-22.24-generic 4.15.17
>   Uname: Linux 4.15.0-22-generic x86_64
>   NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
>   ApportVersion: 2.20.9-0ubuntu7.1
>   Architecture: amd64
>   CurrentDesktop: ubuntu:GNOME
>   Date: Sun Jun 17 10:12:58 2018
>   InstallationDate: Installed on 2017-08-06 (314 days ago)
>   InstallationMedia: Ubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
>   ProcEnviron:
>    TERM=xterm-256color
>    PATH=(custom, no user)
>    XDG_RUNTIME_DIR=<set>
>    LANG=en_US.UTF-8
>    SHELL=/bin/bash
>   SourcePackage: linux-signed
>   UpgradeStatus: Upgraded to bionic on 2018-05-29 (19 days ago)
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1777338/+subscriptions