Public bug reported:
**Title:** Linux 7.0.0-42-generic: intermittent boot failure with NULL
instruction pointer in PCI bus notifier during driver probing on
Gigabyte Z890
### Summary
Ubuntu 24.04 / Kubuntu intermittently fails to initialize properly when
booting kernel `7.0.0-42-generic` (`7.0.0-42.42~24.04.1`, upstream
7.0.14).
The kernel encounters three NULL instruction-pointer faults during PCI
driver probing. All three crashes follow the same notifier path:
```
RIP: 0010:0x0
notifier_call_chain+0x61/0xf0
blocking_notifier_call_chain+0x41/0x70
bus_notify+0x37/0x60
driver_sysfs_add+0x1b/0xd0
really_probe+0xa6/0x350
```
The crashes occur in different execution contexts, including Intel NPU
driver registration, asynchronous driver attachment, and Intel processor
thermal driver registration.
Subsequently, udev initialization stalls, multiple workers are killed,
and system services fail to start.
### Hardware and software
- Distribution: Kubuntu / Ubuntu 24.04 kernel package
- Kernel: `7.0.0-42-generic`
- Package: `7.0.0-42.42~24.04.1`
- Upstream kernel base: 7.0.14
- Motherboard: Gigabyte Z890 AORUS ELITE X ICE
- BIOS: F19, dated 2026-02-02
- Realtek RTL8125 2.5GbE Ethernet controller
- Realtek `r8125` DKMS module version 9.011.00 installed
- In-kernel `r8169` also present; Ethernet device bound to `r8169` during a
successful boot
### Reproduction
1. Boot the machine using kernel `7.0.0-42-generic`.
2. On some boots, multiple kernel Oops events occur during driver
initialization.
3. Device initialization subsequently stalls.
4. udev and other services time out or fail.
5. Other boots complete successfully, and the kernel can remain running for
days.
The issue is intermittent. No reliable reproduction frequency has been
established.
### Expected behavior
The kernel should initialize PCI drivers and complete the boot without
kernel Oops events or stalled device initialization.
### Actual behavior
On 2026-11-03 at approximately 10:26:31 EST, the following errors were
recorded:
```
BUG: kernel NULL pointer dereference,
address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
RIP: 0010:0x0
```
**Crash #1**
- CPU: 1
- Process: `(udev-worker)`, PID 1728
- Driver registration: `ivpu_pci_driver_init [intel_vpu]`
- Failure: `notifier_call_chain+0x61/0xf0`
**Crash #2**
- CPU: 0
- Process: `kworker/u56:9`, PID 350
- Workqueue: `async async_run_entry_fn`
- Driver attachment: `__driver_attach_async_helper`
- Failure: `notifier_call_chain+0x61/0xf0`
**Crash #3**
- CPU: 5
- Process: `(udev-worker)`, PID 1743
- Driver registration: `proc_thermal_pci_driver_init
[processor_thermal_device_pci]`
- Failure: `notifier_call_chain+0x61/0xf0`
All three crashes have the same call-path offsets and show the same
`RDI` register value:
```
RDI: ffff8c8883660f80
```
The kernel was tainted with `O` and `E` before the first crash,
indicating an out-of-tree unsigned module. Subsequent crashes also show
`D`, indicating an earlier Oops.
The Realtek `r8125` DKMS module was loaded. Its involvement has not been
established.
### Consequences
Following the faults:
- `systemd-udev-settle.service` timed out.
- Numerous udev workers were killed.
- Several systemd services failed, including `systemd-resolved`,
`systemd-timesyncd`, and `systemd-oomd`.
- Further driver initialization and service startup failures occurred.
### Additional observations
The kernel was booted with:
```
module_blacklist=intel_vsec
```
This workaround did not prevent the crashes. It has since been removed
from the generated GRUB configuration, but it was active during the
recorded failure.
On a successful boot of the same kernel, the Intel NPU driver
subsequently reported runtime power-management timeouts:
```
ivpu_ipc_send_receive_internal():
IPC receive failed: type VPU_JSM_MSG_PWR_D0I3_ENTER, ret -110
ivpu_pm_runtime_suspend_cb():
Failed to prepare for d0i3: -110
```
These later NPU errors may be independent of the original notifier
failure.
The Ubuntu kernel configuration contains:
```
# CONFIG_DEBUG_NOTIFIERS is not set
```
### Preliminary analysis
The common failure location across three different driver-probing
contexts suggests an invalid or corrupted callback in a shared bus
notifier chain.
Although Intel VPU initialization triggers the first observed crash, the
subsequent failures indicate that the underlying defect may not reside
within the Intel VPU driver.
No offending notifier owner has been established.
### Requested investigation
Please investigate the PCI bus notifier chain, particularly callback
registration and invocation during `driver_sysfs_add()` /
`BUS_NOTIFY_BIND_DRIVER`.
Full kernel logs from the failed boot are available for attachment.
The system remains available for additional diagnostics, and kernel
6.17.0-40 is retained as a fallback.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-7.0.0-42-generic 7.0.0-42.42~24.04.1
ProcVersionSignature: Ubuntu 7.0.0-42.42~24.04.1-generic 7.0.14
Uname: Linux 7.0.0-42-generic x86_64
ApportVersion: 2.28.3-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: pepper 5309 F.... wireplumber
/dev/snd/controlC0: pepper 5309 F.... wireplumber
/dev/snd/seq: pepper 5305 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Thu Nov 5 12:22:29 2026
InstallationDate: Installed on 2025-10-04 (398 days ago)
InstallationMedia: Kubuntu 24.04.3 LTS "Noble Numbat" - Release amd64
(20250805.1)
MachineType: Gigabyte Technology Co., Ltd. Z890 AORUS ELITE X ICE
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-42-generic
root=UUID=affff63a-c833-4b7c-abf2-3363dbbbb794 ro module_blacklist=intel_vsec
quiet
cryptdevice=UUID=782b5ffc-97c0-47dc-9a17-c7f295ef6f9b:luks-782b5ffc-97c0-47dc-9a17-c7f295ef6f9b
root=/dev/mapper/luks-782b5ffc-97c0-47dc-9a17-c7f295ef6f9b splash quiet splash
vt.handoff=7 vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
RebootRequiredPkgs: Error: path contained symlinks.
RelatedPackageVersions:
linux-restricted-modules-7.0.0-42-generic N/A
linux-backports-modules-7.0.0-42-generic N/A
linux-firmware 20240318.git3b128b60.0ubuntu3.1
SourcePackage: linux-hwe-7.0
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/02/2026
dmi.bios.release: 5.32
dmi.bios.vendor: American Megatrends International, LLC.
dmi.bios.version: F19
dmi.board.asset.tag: Default string
dmi.board.name: Z890 AORUS ELITE X ICE
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:bvnAmericanMegatrendsInternational,LLC.:bvrF19:bd02/02/2026:br5.32:svnGigabyteTechnologyCo.,Ltd.:pnZ890AORUSELITEXICE:pvr-CF-WCP-IDO:rvnGigabyteTechnologyCo.,Ltd.:rnZ890AORUSELITEXICE:rvrx.x:cvnDefaultstring:ct3:cvrDefaultstring:skuDefaultstring:pfaZ890MB:
dmi.product.family: Z890 MB
dmi.product.name: Z890 AORUS ELITE X ICE
dmi.product.sku: Default string
dmi.product.version: -CF-WCP-IDO
dmi.sys.vendor: Gigabyte Technology Co., Ltd.
** Affects: linux-hwe-7.0 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble
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https://bugs.launchpad.net/bugs/2173161
Title:
Linux 7.0.0-42-generic: intermittent boot failure
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