Note: English is not my first language and I have used AI assistance to write this report. The technical content is accurate and based on my own testing.
Hardware:
Lenovo ThinkPad E14 Gen 7 (21U2CTO1WW)
CPU: Intel Core Ultra 7 258V (Lunar Lake, family 0x6, model 0xbd, stepping 0x1)
RAM: 32 GB
BIOS: R34ET40W 1.40 (2026-04-30)
Software:
OS: Fedora Linux 44
Kernel: 7.0.10-201.fc44.x86_64
Description:
The system crashes randomly with a kernel NULL pointer dereference inside cpuidle_enter_state. The crash always occurs on CPU 5, which is a Low Power E-core (LP E-core) on Lunar Lake.
The crash is triggered by power state transitions — most notably s2idle resume and plugging/unplugging the charger — but can also happen during normal usage.
Call trace:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
CPU: 5 UID: 0 PID: 0 Comm: swapper/5
RIP: 0010:0x0
__timekeeping_advance+0x53f/0x570
update_wall_time+0x33/0x130
tick_nohz_update_jiffies+0x22/0x40
irq_enter_rcu+0x73/0x90
sysvec_apic_timer_interrupt+0x64/0x90
asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:cpuidle_enter_state+0xcd/0x6a0
cpuidle_enter+0x31/0x50
cpuidle_idle_call+0x10f/0x200
do_idle+0x9c/0x100
cpu_startup_entry+0x29/0x30
start_secondary+0x126/0x180
common_startup_64+0x13e/0x141
Workaround:
Disabling CPU 5 completely eliminates the crashes:
echo 0 > /sys/devices/system/cpu/cpu5/online
Before this workaround the system was crashing at least once every one or two days. After several days with CPU 5 offline, there have been no crashes at all. To make it persistent across reboots I am using a systemd oneshot service that disables CPU 5 at boot.
Note: English is not my first language and I have used AI assistance to write this report. The technical content is accurate and based on my own testing.
Hardware:
Lenovo ThinkPad E14 Gen 7 (21U2CTO1WW)
CPU: Intel Core Ultra 7 258V (Lunar Lake, family 0x6, model 0xbd, stepping 0x1)
RAM: 32 GB
BIOS: R34ET40W 1.40 (2026-04-30)
Software:
OS: Fedora Linux 44
Kernel: 7.0.10-201.fc44.x86_64
Description:
The system crashes randomly with a kernel NULL pointer dereference inside cpuidle_enter_state. The crash always occurs on CPU 5, which is a Low Power E-core (LP E-core) on Lunar Lake.
The crash is triggered by power state transitions — most notably s2idle resume and plugging/unplugging the charger — but can also happen during normal usage.
Call trace:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
CPU: 5 UID: 0 PID: 0 Comm: swapper/5
RIP: 0010:0x0
__timekeeping_advance+0x53f/0x570
update_wall_time+0x33/0x130
tick_nohz_update_jiffies+0x22/0x40
irq_enter_rcu+0x73/0x90
sysvec_apic_timer_interrupt+0x64/0x90
asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:cpuidle_enter_state+0xcd/0x6a0
cpuidle_enter+0x31/0x50
cpuidle_idle_call+0x10f/0x200
do_idle+0x9c/0x100
cpu_startup_entry+0x29/0x30
start_secondary+0x126/0x180
common_startup_64+0x13e/0x141
Workaround:
Disabling CPU 5 completely eliminates the crashes:
echo 0 > /sys/devices/system/cpu/cpu5/online
Before this workaround the system was crashing at least once every one or two days. After several days with CPU 5 offline, there have been no crashes at all. To make it persistent across reboots I am using a systemd oneshot service that disables CPU 5 at boot.