That one works. On to 5856293c78e552c012835e667d66775bba20b4f7.

I suspect 3f6a3b035f91 and abd39ac1da07 may be the real problem, since
the CPU I am using is an AMD Ryzen chip, and those are tinkering
specifically with how the kernel handles those.

On Fri, Jul 20, 2018 at 10:23 PM, Adam Novak <email address hidden> wrote:
> 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