SRU request submitted:
https://lists.ubuntu.com/archives/kernel-team/2018-August/094683.html
** Description changed:
+ == SRU Justification ==
+ Mainline commit 1f50ddb4f418 introduced a regression. That commit added
+ speculative_store_bypass_ht_init() to the per-CPU initialization sequence.
+ However, speculative_store_bypass_ht_init() needs to be called on each CPU for
+ PV guests, as well.
+
+ The regresssion prevents systems from booting.
+
+ The patch to fix this regression has also been cc'd to upstream stable,
+ but it has not landed in Bionic as of yet.
+
+ == Fix ==
+ 74899d92e666 ("x86/xen: Add call of speculative_store_bypass_ht_init() to PV
paths")
+
+ == Regression Potential ==
+ Low. This patch fixes a current regressionThis patch has also been
+ submitted to upstream stable, so it has had additional upstream review.
+
+ == Test Case ==
+ A test kernel was built with this patch and tested by the original bug
reporter.
+ The bug reporter states the test kernel resolved the bug.
+
+
+
+
+
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
+ 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)
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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
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