OK, I tried that one and it still exhibited the issue. I'm going to
try 91762b4035d9da8c266e2cb3dbc552052434bbf0 next.

On Fri, Jul 20, 2018 at 9:08 PM, Adam Novak <email address hidden> wrote:
> 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