[Bug 2171543] Re: linux 7.0.0-38: hard lockup when idle on Sandy Bridge W520, 6.8.0-146 unaffected

** Tags added: kernel-daily-bug -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb 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 Status in linux package in Ubuntu: New Bug description: 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 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2171543/+subscriptions