Re: amd-iommu/x2apic: sleeping function called from invalid context

Thomas Gleixner
2017-07-26T10:42:59Z

On Tue, 25 Jul 2017, Artem Savkov wrote:

> Hi,
>
> Commit 1c3c5ea "sched/core: Enable might_sleep() and smp_processor_id()
> checks early" seem to have uncovered an issue with amd-iommu/x2apic.
>
> Starting with that commit the following warning started to show up on AMD
> systems during boot:

> [ 0.160000] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747

> [ 0.160000] mutex_lock_nested+0x1b/0x20
> [ 0.160000] register_syscore_ops+0x1d/0x70
> [ 0.160000] state_next+0x119/0x910
> [ 0.160000] iommu_go_to_state+0x29/0x30
> [ 0.160000] amd_iommu_enable+0x13/0x23
> [ 0.160000] irq_remapping_enable+0x1b/0x39
> [ 0.160000] enable_IR_x2apic+0x91/0x196
> [ 0.160000] default_setup_apic_routing+0x16/0x6e
> [ 0.160000] native_smp_prepare_cpus+0x257/0x2d5

Yep, that's clearly stupid. The completely untested patch below should cure
the issue.

Thanks,

tglx

8<---------------

--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2440,7 +2440,6 @@ static int __init state_next(void)
break;
case IOMMU_ACPI_FINISHED:
early_enable_iommus();
- register_syscore_ops(&amd_iommu_syscore_ops);
x86_platform.iommu_shutdown = disable_iommus;
init_state = IOMMU_ENABLED;
break;
@@ -2559,6 +2558,8 @@ static int __init amd_iommu_init(void)
for_each_iommu(iommu)
iommu_flush_all_caches(iommu);
}
+ } else {
+ register_syscore_ops(&amd_iommu_syscore_ops);
}

return ret;