diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index bad25b0..d018d95 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -97,7 +97,7 @@ struct acpi_ioremap {
 };
 
 static LIST_HEAD(acpi_ioremaps);
-static DEFINE_MUTEX(acpi_ioremap_lock);
+static DEFINE_SPINLOCK(acpi_ioremap_lock);
 
 static void __init acpi_osi_setup_late(void);
 
@@ -267,13 +267,13 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
 	}
 }
 
-/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */
+/* Must be called with 'acpi_ioremap_lock'. */
 static struct acpi_ioremap *
 acpi_map_lookup(acpi_physical_address phys, acpi_size size)
 {
 	struct acpi_ioremap *map;
 
-	list_for_each_entry_rcu(map, &acpi_ioremaps, list)
+	list_for_each_entry(map, &acpi_ioremaps, list)
 		if (map->phys <= phys &&
 		    phys + size <= map->phys + map->size)
 			return map;
@@ -281,7 +281,7 @@ acpi_map_lookup(acpi_physical_address phys, acpi_size size)
 	return NULL;
 }
 
-/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */
+/* Must be called with 'acpi_ioremap_lock'. */
 static void __iomem *
 acpi_map_vaddr_lookup(acpi_physical_address phys, unsigned int size)
 {
@@ -298,29 +298,29 @@ void __iomem *acpi_os_get_iomem(acpi_physical_address phys, unsigned int size)
 {
 	struct acpi_ioremap *map;
 	void __iomem *virt = NULL;
+	unsigned long flags;
 
-	mutex_lock(&acpi_ioremap_lock);
+	spin_lock_irqsave(&acpi_ioremap_lock, flags);
 	map = acpi_map_lookup(phys, size);
 	if (map) {
 		virt = map->virt + (phys - map->phys);
 		map->refcount++;
 	}
-	mutex_unlock(&acpi_ioremap_lock);
+	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 	return virt;
 }
 EXPORT_SYMBOL_GPL(acpi_os_get_iomem);
 
-/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */
+/* Must be called with 'acpi_ioremap_lock'. */
 static struct acpi_ioremap *
 acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
 {
 	struct acpi_ioremap *map;
 
-	list_for_each_entry_rcu(map, &acpi_ioremaps, list)
+	list_for_each_entry(map, &acpi_ioremaps, list)
 		if (map->virt <= virt &&
 		    virt + size <= map->virt + map->size)
 			return map;
-
 	return NULL;
 }
 
@@ -362,6 +362,7 @@ acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
 	void __iomem *virt;
 	acpi_physical_address pg_off;
 	acpi_size pg_sz;
+	unsigned long flags;
 
 	if (phys > ULONG_MAX) {
 		printk(KERN_ERR PREFIX "Cannot map memory that high\n");
@@ -371,7 +372,7 @@ acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
 	if (!acpi_gbl_permanent_mmap)
 		return __acpi_map_table((unsigned long)phys, size);
 
-	mutex_lock(&acpi_ioremap_lock);
+	spin_lock_irqsave(&acpi_ioremap_lock, flags);
 	/* Check if there's a suitable mapping already. */
 	map = acpi_map_lookup(phys, size);
 	if (map) {
@@ -381,7 +382,7 @@ acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
 
 	map = kzalloc(sizeof(*map), GFP_KERNEL);
 	if (!map) {
-		mutex_unlock(&acpi_ioremap_lock);
+		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 		return NULL;
 	}
 
@@ -389,7 +390,7 @@ acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
 	pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off;
 	virt = acpi_map(pg_off, pg_sz);
 	if (!virt) {
-		mutex_unlock(&acpi_ioremap_lock);
+		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 		kfree(map);
 		return NULL;
 	}
@@ -400,10 +401,10 @@ acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
 	map->size = pg_sz;
 	map->refcount = 1;
 
-	list_add_tail_rcu(&map->list, &acpi_ioremaps);
+	list_add_tail(&map->list, &acpi_ioremaps);
 
 out:
-	mutex_unlock(&acpi_ioremap_lock);
+	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 	return map->virt + (phys - map->phys);
 }
 EXPORT_SYMBOL_GPL(acpi_os_map_iomem);
@@ -418,13 +419,12 @@ EXPORT_SYMBOL_GPL(acpi_os_map_memory);
 static void acpi_os_drop_map_ref(struct acpi_ioremap *map)
 {
 	if (!--map->refcount)
-		list_del_rcu(&map->list);
+		list_del(&map->list);
 }
 
 static void acpi_os_map_cleanup(struct acpi_ioremap *map)
 {
 	if (!map->refcount) {
-		synchronize_rcu();
 		acpi_unmap(map->phys, map->virt);
 		kfree(map);
 	}
@@ -433,21 +433,22 @@ static void acpi_os_map_cleanup(struct acpi_ioremap *map)
 void __ref acpi_os_unmap_iomem(void __iomem *virt, acpi_size size)
 {
 	struct acpi_ioremap *map;
+	unsigned long flags;
 
 	if (!acpi_gbl_permanent_mmap) {
 		__acpi_unmap_table(virt, size);
 		return;
 	}
 
-	mutex_lock(&acpi_ioremap_lock);
+	spin_lock_irqsave(&acpi_ioremap_lock, flags);
 	map = acpi_map_lookup_virt(virt, size);
 	if (!map) {
-		mutex_unlock(&acpi_ioremap_lock);
+		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 		WARN(true, PREFIX "%s: bad address %p\n", __func__, virt);
 		return;
 	}
 	acpi_os_drop_map_ref(map);
-	mutex_unlock(&acpi_ioremap_lock);
+	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 
 	acpi_os_map_cleanup(map);
 }
@@ -490,6 +491,7 @@ void acpi_os_unmap_generic_address(struct acpi_generic_address *gas)
 {
 	u64 addr;
 	struct acpi_ioremap *map;
+	unsigned long flags;
 
 	if (gas->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
 		return;
@@ -499,14 +501,14 @@ void acpi_os_unmap_generic_address(struct acpi_generic_address *gas)
 	if (!addr || !gas->bit_width)
 		return;
 
-	mutex_lock(&acpi_ioremap_lock);
+	spin_lock_irqsave(&acpi_ioremap_lock, flags);
 	map = acpi_map_lookup(addr, gas->bit_width / 8);
 	if (!map) {
-		mutex_unlock(&acpi_ioremap_lock);
+		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 		return;
 	}
 	acpi_os_drop_map_ref(map);
-	mutex_unlock(&acpi_ioremap_lock);
+	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 
 	acpi_os_map_cleanup(map);
 }
@@ -939,11 +941,12 @@ acpi_os_read_memory(acpi_physical_address phys_addr, u64 *value, u32 width)
 	unsigned int size = width / 8;
 	bool unmap = false;
 	u64 dummy;
+	unsigned long flags;
 
-	rcu_read_lock();
+	spin_lock_irqsave(&acpi_ioremap_lock, flags);
 	virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
 	if (!virt_addr) {
-		rcu_read_unlock();
+		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 		virt_addr = acpi_os_ioremap(phys_addr, size);
 		if (!virt_addr)
 			return AE_BAD_ADDRESS;
@@ -973,7 +976,7 @@ acpi_os_read_memory(acpi_physical_address phys_addr, u64 *value, u32 width)
 	if (unmap)
 		iounmap(virt_addr);
 	else
-		rcu_read_unlock();
+		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 
 	return AE_OK;
 }
@@ -997,11 +1000,12 @@ acpi_os_write_memory(acpi_physical_address phys_addr, u64 value, u32 width)
 	void __iomem *virt_addr;
 	unsigned int size = width / 8;
 	bool unmap = false;
+	unsigned long flags;
 
-	rcu_read_lock();
+	spin_lock_irqsave(&acpi_ioremap_lock, flags);
 	virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
 	if (!virt_addr) {
-		rcu_read_unlock();
+		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 		virt_addr = acpi_os_ioremap(phys_addr, size);
 		if (!virt_addr)
 			return AE_BAD_ADDRESS;
@@ -1028,7 +1032,7 @@ acpi_os_write_memory(acpi_physical_address phys_addr, u64 value, u32 width)
 	if (unmap)
 		iounmap(virt_addr);
 	else
-		rcu_read_unlock();
+		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
 
 	return AE_OK;
 }
