This reverts commit 367c820ef08082e68df8a3bc12e62393af21e4b5. lockup_detector_init() makes heavy use of per-cpu variables and must be called with preemption disabled. Usually, it's handled early during boot in kernel_init_freeable(), before SMP has been initialised. Since we do not know whether or not our PMU interrupt can be signalled as an NMI until considerably later in the boot process, the Arm PMU driver attempts to re-initialise the lockup detector off the back of a device_initcall(). Unfortunately, this is called from preemptible context and results in the following splat: | BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 | caller is debug_smp_processor_id+0x20/0x2c | CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.10.0+ #276 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0x0/0x3c0 | show_stack+0x20/0x6c | dump_stack+0x2f0/0x42c | check_preemption_disabled+0x1cc/0x1dc | debug_smp_processor_id+0x20/0x2c | hardlockup_detector_event_create+0x34/0x18c | hardlockup_detector_perf_init+0x2c/0x134 | watchdog_nmi_probe+0x18/0x24 | lockup_detector_init+0x44/0xa8 | armv8_pmu_driver_init+0x54/0x78 | do_one_initcall+0x184/0x43c | kernel_init_freeable+0x368/0x380 | kernel_init+0x1c/0x1cc | ret_from_fork+0x10/0x30 Rather than bodge this with raw_smp_processor_id() or randomly disabling preemption, simply revert the culprit for now until we figure out how to do this properly.
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| @@ -163,8 +163,6 @@ int arm_pmu_acpi_probe(armpmu_init_fn init_fn); · 162 unmodified lines | |||
| 163 | static inline int arm_pmu_acpi_probe(armpmu_init_fn init_fn) { return 0; } | 163 | static inline int arm_pmu_acpi_probe(armpmu_init_fn init_fn) { return 0; } |
| 164 | #endif | 164 | #endif |
| 165 | 165 | ||
| 166 | bool arm_pmu_irq_is_nmi(void); | ||
| 167 | |||
| 168 | /* Internal functions only for core arm_pmu code */ | 166 | /* Internal functions only for core arm_pmu code */ |
| 169 | struct arm_pmu *armpmu_alloc(void); | 167 | struct arm_pmu *armpmu_alloc(void); |
| 170 | struct arm_pmu *armpmu_alloc_atomic(void); | 168 | struct arm_pmu *armpmu_alloc_atomic(void); |