multipathd.service fails to start with linux-kvm kernel

[Seth Forshee]

SRU Justification

Impact: multipath-tools is installed by default in server images. With the linux-kvm kernel, multipathd.service fails to start because we do not build dm-multipath in linux-kvm.

Fix: Enable the dm-multipath modules in linux-kvm.

Test Case: Booting the kvm kernel with these modules enabled allows multipathd.service to start successfully.

Regression Potential: This adds a new module which is loaded my multipathd.service. However it's not really going to be utilized unless it is wanted, and as this module is shipped with our other kernels without issue the risk of regressions is low.

---

When doing a dist-upgrade in a vm running the linux-kvm kernel, multipath-tools failed because multipathd.service failed to start.

Setting up multipath-tools (0.8.3-1ubuntu2) ...
Job for multipathd.service failed because the control process exited with error code.
See "systemctl status multipathd.service" and "journalctl -xe" for details.
invoke-rc.d: initscript multipath-tools, action "start" failed.
● multipathd.service - Device-Mapper Multipath Device Controller
     Loaded: loaded (/lib/systemd/system/multipathd.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Mon 2020-04-20 16:49:35 UTC; 7ms ago
TriggeredBy: ● multipathd.socket
    Process: 800 ExecStartPre=/sbin/modprobe -a scsi_dh_alua scsi_dh_emc scsi_dh_rdac dm-multipath (code=exited, status=1/FAILURE)
    Process: 801 ExecStart=/sbin/multipathd -d -s (code=exited, status=1/FAILURE)
   Main PID: 801 (code=exited, status=1/FAILURE)
     Status: "configure"

Apr 20 16:49:35 ff-kvm modprobe[800]: modprobe: WARNING: Module scsi_dh_emc not found in directory /lib/modules/5.4.0-1008-kvm
Apr 20 16:49:35 ff-kvm modprobe[800]: modprobe: WARNING: Module scsi_dh_rdac not found in directory /lib/modules/5.4.0-1008-kvm
Apr 20 16:49:35 ff-kvm modprobe[800]: modprobe: WARNING: Module dm-multipath not found in directory /lib/modules/5.4.0-1008-kvm
Apr 20 16:49:35 ff-kvm multipathd[801]: --------start up--------
Apr 20 16:49:35 ff-kvm multipathd[801]: read /etc/multipath.conf
Apr 20 16:49:35 ff-kvm multipathd[801]: DM multipath kernel driver not loaded
Apr 20 16:49:35 ff-kvm multipathd[801]: DM multipath kernel driver not loaded
Apr 20 16:49:35 ff-kvm systemd[1]: multipathd.service: Main process exited, code=exited, status=1/FAILURE
Apr 20 16:49:35 ff-kvm systemd[1]: multipathd.service: Failed with result 'exit-code'.
Apr 20 16:49:35 ff-kvm systemd[1]: Failed to start Device-Mapper Multipath Device Controller.
dpkg: error processing package multipath-tools (--configure):
 installed multipath-tools package post-installation script subprocess returned error exit status 1
dpkg: dependency problems prevent configuration of ubuntu-server:
 ubuntu-server depends on multipath-tools; however:
  Package multipath-tools is not configured yet.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: multipath-tools 0.8.3-1ubuntu2
ProcVersionSignature: User Name 5.4.0-1008.8-kvm 5.4.30
Uname: Linux 5.4.0-1008-kvm x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
Date: Mon Apr 20 16:57:37 2020
ProcEnviron:
 TERM=screen-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
SourcePackage: multipath-tools
UpgradeStatus: No upgrade log present (probably fresh install)

[Seth Forshee (sforshee)]

Confirmed that shipping the dm-multipath module for this kernel clears up the issue.

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-kvm - 5.4.0-1009.9

---------------
linux-kvm (5.4.0-1009.9) focal; urgency=medium

  * focal/linux-kvm: 5.4.0-1009.9 -proposed tracker (LP: #1873934)

  * multipathd.service fails to start with linux-kvm kernel (LP: #1873912)
    - [Config] Enable dm-multipath modules

  * Make linux-kvm bootable in LXD VMs (LP: #1873809)
    - [Config] CONFIG_EFI_STUB=y
    - [Config] Enable vsocket config options

 -- Seth Forshee <email address hidden> Mon, 20 Apr 2020 14:30:41 -0500