diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index ee4cb1906e45..b0df78f9cd28 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -53,6 +53,7 @@ struct acpi_table_header * __initdata dmar_tbl;
 static acpi_size dmar_tbl_size;
 
 static int alloc_iommu(struct dmar_drhd_unit *drhd);
+static void free_iommu(struct intel_iommu *iommu);
 
 static void __init dmar_register_drhd_unit(struct dmar_drhd_unit *drhd)
 {
@@ -205,25 +206,28 @@ dmar_parse_one_drhd(struct acpi_dmar_header *header)
 	return 0;
 }
 
+static void dmar_free_drhd(struct dmar_drhd_unit *dmaru)
+{
+	if (dmaru->devices && dmaru->devices_cnt)
+		dmar_free_dev_scope(&dmaru->devices, &dmaru->devices_cnt);
+	if (dmaru->iommu)
+		free_iommu(dmaru->iommu);
+	kfree(dmaru);
+}
+
 static int __init dmar_parse_dev(struct dmar_drhd_unit *dmaru)
 {
 	struct acpi_dmar_hardware_unit *drhd;
-	int ret = 0;
 
 	drhd = (struct acpi_dmar_hardware_unit *) dmaru->hdr;
 
 	if (dmaru->include_all)
 		return 0;
 
-	ret = dmar_parse_dev_scope((void *)(drhd + 1),
-				((void *)drhd) + drhd->header.length,
-				&dmaru->devices_cnt, &dmaru->devices,
-				drhd->segment);
-	if (ret) {
-		list_del(&dmaru->list);
-		kfree(dmaru);
-	}
-	return ret;
+	return dmar_parse_dev_scope((void *)(drhd + 1),
+				    ((void *)drhd) + drhd->header.length,
+				    &dmaru->devices_cnt, &dmaru->devices,
+				    drhd->segment);
 }
 
 #ifdef CONFIG_ACPI_NUMA
@@ -435,7 +439,7 @@ dmar_find_matched_drhd_unit(struct pci_dev *dev)
 int __init dmar_dev_scope_init(void)
 {
 	static int dmar_dev_scope_initialized;
-	struct dmar_drhd_unit *drhd, *drhd_n;
+	struct dmar_drhd_unit *drhd;
 	int ret = -ENODEV;
 
 	if (dmar_dev_scope_initialized)
@@ -444,7 +448,7 @@ int __init dmar_dev_scope_init(void)
 	if (list_empty(&dmar_drhd_units))
 		goto fail;
 
-	list_for_each_entry_safe(drhd, drhd_n, &dmar_drhd_units, list) {
+	list_for_each_entry(drhd, &dmar_drhd_units, list) {
 		ret = dmar_parse_dev(drhd);
 		if (ret)
 			goto fail;
@@ -725,12 +729,13 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
 	return err;
 }
 
-void free_iommu(struct intel_iommu *iommu)
+static void free_iommu(struct intel_iommu *iommu)
 {
-	if (!iommu)
-		return;
-
-	free_dmar_iommu(iommu);
+	if (iommu->irq) {
+		free_irq(iommu->irq, iommu);
+		irq_set_handler_data(iommu->irq, NULL);
+		destroy_irq(iommu->irq);
+	}
 
 	if (iommu->reg)
 		unmap_iommu(iommu);
@@ -1368,4 +1373,21 @@ int __init dmar_ir_support(void)
 	return dmar->flags & 0x1;
 }
 
+static int __init dmar_free_unused_resources(void)
+{
+	struct dmar_drhd_unit *dmaru, *dmaru_n;
+
+	/* DMAR units are in use */
+	if (irq_remapping_enabled || intel_iommu_enabled)
+		return 0;
+
+	list_for_each_entry_safe(dmaru, dmaru_n, &dmar_drhd_units, list) {
+		list_del(&dmaru->list);
+		dmar_free_drhd(dmaru);
+	}
+
+	return 0;
+}
+
+late_initcall(dmar_free_unused_resources);
 IOMMU_INIT_POST(detect_intel_iommu);
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 7a0984d1c8d5..fd9e369a8cf7 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1265,7 +1265,7 @@ static int iommu_init_domains(struct intel_iommu *iommu)
 static void domain_exit(struct dmar_domain *domain);
 static void vm_domain_exit(struct dmar_domain *domain);
 
-void free_dmar_iommu(struct intel_iommu *iommu)
+static void free_dmar_iommu(struct intel_iommu *iommu)
 {
 	struct dmar_domain *domain;
 	int i;
@@ -1290,15 +1290,10 @@ void free_dmar_iommu(struct intel_iommu *iommu)
 	if (iommu->gcmd & DMA_GCMD_TE)
 		iommu_disable_translation(iommu);
 
-	if (iommu->irq) {
-		/* This will mask the irq */
-		free_irq(iommu->irq, iommu);
-		irq_set_handler_data(iommu->irq, NULL);
-		destroy_irq(iommu->irq);
-	}
-
 	kfree(iommu->domains);
 	kfree(iommu->domain_ids);
+	iommu->domains = NULL;
+	iommu->domain_ids = NULL;
 
 	g_iommus[iommu->seq_id] = NULL;
 
@@ -2627,7 +2622,7 @@ static int __init init_dmars(void)
 	return 0;
 error:
 	for_each_active_iommu(iommu, drhd)
-		free_iommu(iommu);
+		free_dmar_iommu(iommu);
 	kfree(g_iommus);
 	return ret;
 }
diff --git a/include/linux/dma_remapping.h b/include/linux/dma_remapping.h
index 57c9a8ae4f2d..7ac17f57250e 100644
--- a/include/linux/dma_remapping.h
+++ b/include/linux/dma_remapping.h
@@ -27,7 +27,6 @@ struct root_entry;
 
 
 #ifdef CONFIG_INTEL_IOMMU
-extern void free_dmar_iommu(struct intel_iommu *iommu);
 extern int iommu_calculate_agaw(struct intel_iommu *iommu);
 extern int iommu_calculate_max_sagaw(struct intel_iommu *iommu);
 extern int dmar_disabled;
@@ -41,9 +40,6 @@ static inline int iommu_calculate_max_sagaw(struct intel_iommu *iommu)
 {
 	return 0;
 }
-static inline void free_dmar_iommu(struct intel_iommu *iommu)
-{
-}
 #define dmar_disabled	(1)
 #define intel_iommu_enabled (0)
 #endif
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index f2c4114b8665..2c4bed593b32 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -348,7 +348,6 @@ static inline void __iommu_flush_cache(
 extern struct dmar_drhd_unit * dmar_find_matched_drhd_unit(struct pci_dev *dev);
 extern int dmar_find_matched_atsr_unit(struct pci_dev *dev);
 
-extern void free_iommu(struct intel_iommu *iommu);
 extern int dmar_enable_qi(struct intel_iommu *iommu);
 extern void dmar_disable_qi(struct intel_iommu *iommu);
 extern int dmar_reenable_qi(struct intel_iommu *iommu);