Public bug reported:
After upgrading from Ubuntu 24.04 to 26.04 this machine hard-locks reliably
while idle. The kernel stops executing entirely: no log entry, no panic, no
MCE. Booting the previous kernel 6.8.0-146-generic on the same 26.04 userspace
makes the problem disappear.
Bad kernel: linux-image-7.0.0-38-generic 7.0.0-38.38
Good kernel: linux-image-6.8.0-146-generic 6.8.0-146.146
SYSTEM
ThinkPad W520 (type 4284W84), BIOS 8BET56WW (1.36)
Intel Core i7-2760QM (Sandy Bridge), microcode 0x2f
intel-microcode 3.20260210.1ubuntu2
32 GB RAM (4 x 8 GB Crucial CT8G3S1339M, 1333 MT/s)
Intel HD 3000 (i915) + NVIDIA Quadro 1000M (nouveau)
Ubuntu 26.04.1 LTS, GNOME on Wayland, legacy BIOS boot, LVM root
SYMPTOMS
Complete hard lockup, always while idle, never under load.
- Screen keeps showing the last rendered frame, no corruption
- Keyboard and mouse dead, including the internal PS/2 keyboard
- SysRq (REISUB) has no effect, kernel.sysrq=1 verified active
- Hard disk LED dark, no I/O
- Mouse LED sometimes off, sometimes lit (varies between occurrences)
- Nothing in the journal, the log simply ends mid-operation
EVIDENCE THAT THE MACHINE TRULY HALTS
A 10-second watchdog logger with fsync after every write, plus the regular
10-minute sysstat-collect timer, were used as a heartbeat. Example, lockup
at 17:08:30: ticks at 16:40, 16:50 and 17:00 are present; the ticks at
17:10, 17:20 and 17:30 are missing, and the machine was not restarted until
17:36. So the kernel stopped executing rather than merely losing input.
TIME TO LOCKUP
7.0.0-38, nouveau loaded ............ 25 min / 35 min / 74 min
7.0.0-38, dGPU disabled in BIOS ..... 2 h 14 / 3 h 30 / 3 h 27
7.0.0-38, intel_idle.max_cstate=1 ... 3 h 27
6.8.0-146, dGPU disabled in BIOS .... 35 h 49 awake, NO LOCKUP
Awake time excludes suspend; measured from gaps in the logger output, not
from uptime. Nine lockups occurred in total under 7.0.0-38.
RULED OUT
Thermal - logger shows 57-74 degC package temperature and load ~1.2 at the
moment of death, throttle counters static for hours
Memory - memtest86+ clean overnight, no EDAC or MCE messages ever
USB - no over-current, disconnect or xHCI errors in the entire journal
history; the dead input includes the internal PS/2 keyboard
C-states - intel_idle.max_cstate=1 verified active via /proc/cmdline and the
cpuidle state list (only POLL and C1 left); no improvement
OOM - 31 GB RAM with about 26 GB available
Storage - HDD LED dark, no I/O stall pattern
NOTE ON NOUVEAU
With nouveau loaded the lockups came roughly four times as often. Disabling
the discrete Quadro 1000M in the BIOS (Integrated Graphics) lengthened the
mean time to failure from about 45 minutes to about 3 hours, but did not
stop them. This looks like an aggravating factor rather than the cause.
REPRODUCTION
1. Boot 7.0.0-38-generic on this hardware
2. Log into a GNOME Wayland session and leave the machine idle
3. Within a few hours the machine hard-locks as described
Booting 6.8.0-146-generic and repeating the same usage does not
reproduce it.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-38-generic 7.0.0-38.38
ProcVersionSignature: Ubuntu 7.0.0-38.38-generic 7.0.14
Uname: Linux 7.0.0-38-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: falk 2515 F.... wireplumber
/dev/snd/seq: falk 2398 F.... pipewire
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Tue Oct 20 21:01:54 2026
InstallationDate: Installed on 2020-01-14 (2471 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
MachineType: LENOVO 4284W84
ProcEnviron:
LANG=de_DE.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-38-generic
root=/dev/mapper/vgubuntu-root ro quiet splash
SourcePackage: linux
UpgradeStatus: Upgraded to resolute on 2026-10-06 (15 days ago)
dmi.bios.date: 01/19/2012
dmi.bios.release: 1.36
dmi.bios.vendor: LENOVO
dmi.bios.version: 8BET56WW (1.36 )
dmi.board.asset.tag: Not Available
dmi.board.name: 4284W84
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.ec.firmware.release: 1.32
dmi.modalias:
dmi:bvnLENOVO:bvr8BET56WW(1.36):bd01/19/2012:br1.36:efr1.32:svnLENOVO:pn4284W84:pvrThinkPadW520:rvnLENOVO:rn4284W84:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:sku:pfaThinkPadW520:
dmi.product.family: ThinkPad W520
dmi.product.name: 4284W84
dmi.product.version: ThinkPad W520
dmi.sys.vendor: LENOVO
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2171543
Title:
linux 7.0.0-38: hard lockup when idle on Sandy Bridge W520, 6.8.0-146
unaffected
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