diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index b093181..c90c76a 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -636,17 +636,21 @@
 acpi_status
 acpi_os_read_memory(acpi_physical_address phys_addr, u32 * value, u32 width)
 {
-	u32 dummy;
 	void __iomem *virt_addr;
-	int size = width / 8, unmap = 0;
+	unsigned int size = width / 8;
+	bool unmap = false;
+	u32 dummy;
 
 	rcu_read_lock();
 	virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
-	rcu_read_unlock();
 	if (!virt_addr) {
+		rcu_read_unlock();
 		virt_addr = acpi_os_ioremap(phys_addr, size);
-		unmap = 1;
+		if (!virt_addr)
+			return AE_BAD_ADDRESS;
+		unmap = true;
 	}
+
 	if (!value)
 		value = &dummy;
 
@@ -666,6 +670,8 @@
 
 	if (unmap)
 		iounmap(virt_addr);
+	else
+		rcu_read_unlock();
 
 	return AE_OK;
 }
@@ -674,14 +680,17 @@
 acpi_os_write_memory(acpi_physical_address phys_addr, u32 value, u32 width)
 {
 	void __iomem *virt_addr;
-	int size = width / 8, unmap = 0;
+	unsigned int size = width / 8;
+	bool unmap = false;
 
 	rcu_read_lock();
 	virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
-	rcu_read_unlock();
 	if (!virt_addr) {
+		rcu_read_unlock();
 		virt_addr = acpi_os_ioremap(phys_addr, size);
-		unmap = 1;
+		if (!virt_addr)
+			return AE_BAD_ADDRESS;
+		unmap = true;
 	}
 
 	switch (width) {
@@ -700,6 +709,8 @@
 
 	if (unmap)
 		iounmap(virt_addr);
+	else
+		rcu_read_unlock();
 
 	return AE_OK;
 }