Hard lockup using 5.3.0.24.28, 5.4.0-13, 5.4.19-050419 on focal

[Dan Watkins]

This happened in the middle of the night when the machine wasn't in active use, and there's nothing immediately preceding it in the journal to suggest a trigger.

(I've attached the relevant part of the journal, will apport-collect once filed.)
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu9
Architecture: amd64
CurrentDesktop: i3
DistroRelease: Ubuntu 20.04
InstallationDate: Installed on 2019-05-07 (208 days ago)
InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
MachineType: Gigabyte Technology Co., Ltd. B450M DS3H
NonfreeKernelModules: nvidia_modeset nvidia
Package: linux-meta (not installed)
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.3.0-24-generic root=/dev/mapper/ubuntu--vg-root ro quiet splash resume=UUID=73909634-a75d-42c9-8f66-a69138690756 vt.handoff=7
ProcVersionSignature: Ubuntu 5.3.0-24.26-generic 5.3.10
RelatedPackageVersions:
 linux-restricted-modules-5.3.0-24-generic N/A
 linux-backports-modules-5.3.0-24-generic N/A
 linux-firmware 1.183.2
RfKill:

Tags: focal
Uname: Linux 5.3.0-24-generic x86_64
UpgradeStatus: Upgraded to focal on 2019-11-15 (16 days ago)
UserGroups: adm boinc cdrom dip docker libvirt lpadmin lxd plugdev sambashare sbuild sudo
_MarkForUpload: True
dmi.bios.date: 01/25/2019
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: F4
dmi.board.asset.tag: Default string
dmi.board.name: B450M DS3H-CF
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF4:bd01/25/2019:svnGigabyteTechnologyCo.,Ltd.:pnB450MDS3H:pvrDefaultstring:rvnGigabyteTechnologyCo.,Ltd.:rnB450MDS3H-CF:rvrx.x:cvnDefaultstring:ct3:cvrDefaultstring:
dmi.product.family: Default string
dmi.product.name: B450M DS3H
dmi.product.sku: Default string
dmi.product.version: Default string
dmi.sys.vendor: Gigabyte Technology Co., Ltd.
modified.conffile..etc.apport.crashdb.conf: [modified]
mtime.conffile..etc.apport.crashdb.conf: 2019-11-25T16:40:26.261317

[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Dan Watkins (oddbloke)]

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[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Kai-Heng Feng (kaihengfeng)]

RCU bug? I guess the best approach is to reproduce it on mainline kernel and raise the issue to RCU mailing list.

[Dan Watkins (oddbloke)]

Thanks for looking at the bug! Which mainline kernel should I look to use? Is https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.4.1/ the right one?

[Kai-Heng Feng (kaihengfeng)]

Yes that's right.

[Dan Watkins (oddbloke)]

I've been using the mainline kernel (5.4.5, specifically) for a few weeks with no instability; I switched back to the -proposed kernel ~a week ago and I've since seen this issue recur. The version I saw this recur on was 5.4.0-13-generic (and I'm now on -14 as a result of the forced reboot).

Is there anything more I can do to assist in addressing this issue?

[Dan Watkins (oddbloke)]

OK, this (or at least some part of it) finally reproduced on an upstream kernel (5.4.19-050419-generic)! I've attached the journal from "[ cut here ]" onwards, with some minor redaction of VPN endpoints.