diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 9ab5371c3538..d66a920b3d9f 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3022,6 +3022,7 @@ static int __init probe_acpi_namespace_devices(void)
 			if (dev->bus != &acpi_bus_type)
 				continue;
 
+			up_read(&dmar_global_lock);
 			adev = to_acpi_device(dev);
 			mutex_lock(&adev->physical_node_lock);
 			list_for_each_entry(pn,
@@ -3031,6 +3032,7 @@ static int __init probe_acpi_namespace_devices(void)
 					break;
 			}
 			mutex_unlock(&adev->physical_node_lock);
+			down_read(&dmar_global_lock);
 
 			if (ret)
 				return ret;