diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 0e3b009..7b2bb94 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1072,6 +1072,7 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
domain->ops = bus->iommu_ops;
domain->type = type;
+ mutex_init(&domain->reserved_mutex);