diff --git a/arch/x86/kernel/io_apic_64.c b/arch/x86/kernel/io_apic_64.c
index 1b8cccb..a054db9 100644
--- a/arch/x86/kernel/io_apic_64.c
+++ b/arch/x86/kernel/io_apic_64.c
@@ -1124,7 +1124,12 @@
 {
 	struct irq_desc *desc;
 
-	desc = irq_to_desc(irq);
+	/* first time to use this irq_desc */
+	if (irq < 16)
+		desc = irq_to_desc(irq);
+	else
+		desc = irq_to_desc_alloc(irq);
+
 	if (trigger)
 		desc->status |= IRQ_LEVEL;
 	else
@@ -1919,6 +1924,9 @@
 		irq = __get_cpu_var(vector_irq)[vector];
 
 		desc = irq_to_desc(irq);
+		if (!desc)
+			continue;
+
 		cfg = irq_cfg(irq);
 		spin_lock(&desc->lock);
 		if (!cfg->move_cleanup_count)
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index f337f87..5d5976e 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -83,7 +83,7 @@
 
 	if (i < nr_irqs) {
 		unsigned any_count = 0;
-		struct irq_desc *desc = __irq_to_desc(i);
+		struct irq_desc *desc = irq_to_desc(i);
 
 		if (!desc)
 			return 0;
@@ -206,7 +206,7 @@
 	stack_overflow_check(regs);
 #endif
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (likely(desc))
 		generic_handle_irq_desc(irq, desc);
 	else {
diff --git a/arch/x86/kernel/irqinit_64.c b/arch/x86/kernel/irqinit_64.c
index cd9f42d..d17fbc2 100644
--- a/arch/x86/kernel/irqinit_64.c
+++ b/arch/x86/kernel/irqinit_64.c
@@ -143,7 +143,8 @@
 	init_8259A(0);
 
 	for (i = 0; i < 16; i++) {
-		struct irq_desc *desc = irq_to_desc(i);
+		/* first time call this irq_desc */
+		struct irq_desc *desc = irq_to_desc_alloc(i);
 
 		desc->status = IRQ_DISABLED;
 		desc->action = NULL;
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 7b59e19..5fe1b01 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -191,7 +191,7 @@
 } ____cacheline_internodealigned_in_smp;
 
 extern struct irq_desc *irq_to_desc(unsigned int irq);
-extern struct irq_desc *__irq_to_desc(unsigned int irq);
+extern struct irq_desc *irq_to_desc_alloc(unsigned int irq);
 
 #ifndef CONFIG_HAVE_SPARSE_IRQ
 
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index a4bb0da..9fc5e69 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -27,7 +27,8 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = irq_to_desc(irq);
+	/* first time to use this irq_desc */
+	desc = irq_to_desc_alloc(irq);
 	if (!desc) {
 		WARN(1, KERN_ERR "Trying to initialize invalid IRQ%d\n", irq);
 		return;
@@ -60,7 +61,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc) {
 		WARN(1, KERN_ERR "Trying to cleanup invalid IRQ%d\n", irq);
 		return;
@@ -92,7 +93,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc) {
 		WARN(1, KERN_ERR "Trying to install chip for IRQ%d\n", irq);
 		return -EINVAL;
@@ -122,7 +123,7 @@
 	unsigned long flags;
 	int ret = -ENXIO;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc) {
 		printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
 		return -ENODEV;
@@ -150,7 +151,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc) {
 		printk(KERN_ERR
 		       "Trying to install controller data for IRQ%d\n", irq);
@@ -176,7 +177,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc) {
 		printk(KERN_ERR
 		       "Trying to install msi data for IRQ%d\n", irq);
@@ -203,7 +204,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc) {
 		printk(KERN_ERR
 		       "Trying to install chip data for IRQ%d\n", irq);
@@ -554,7 +555,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc) {
 		printk(KERN_ERR
 		       "Trying to install type control for IRQ%d\n", irq);
@@ -618,7 +619,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc) {
 		printk(KERN_ERR "Trying to mark IRQ%d non-probeable\n", irq);
 
@@ -635,7 +636,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc) {
 		printk(KERN_ERR "Trying to mark IRQ%d probeable\n", irq);
 
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index e1d787e..d44e351 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -151,7 +151,7 @@
 struct irq_desc *sparse_irqs;
 DEFINE_DYN_ARRAY(sparse_irqs, sizeof(struct irq_desc), nr_irq_desc, PAGE_SIZE, init_work);
 
-struct irq_desc *__irq_to_desc(unsigned int irq)
+struct irq_desc *irq_to_desc(unsigned int irq)
 {
 	struct irq_desc *desc;
 
@@ -169,7 +169,7 @@
 	}
 	return NULL;
 }
-struct irq_desc *irq_to_desc(unsigned int irq)
+struct irq_desc *irq_to_desc_alloc(unsigned int irq)
 {
 	struct irq_desc *desc, *desc_pri;
 	int i;
@@ -186,6 +186,7 @@
 
 		if (desc->irq == -1U) {
 			desc->irq = irq;
+			printk(KERN_DEBUG "found new irq_desc for irq %d\n", desc->irq);
 			return desc;
 		}
 		desc_pri = desc;
@@ -236,21 +237,7 @@
 
 	desc->irq = irq;
 	desc_pri->next = desc;
-	{
-		/* double check if some one mess up the list */
-		struct irq_desc *desc;
-		int count = 0;
-
-		desc = &sparse_irqs[0];
-		while (desc) {
-			printk(KERN_DEBUG "1 found irq_desc for irq %d\n", desc->irq);
-			if (desc->next)
-				printk(KERN_DEBUG "1 found irq_desc for irq %d and next will be irq %d\n", desc->irq, desc->next->irq);
-			desc = desc->next;
-			count++;
-		}
-		printk(KERN_DEBUG "1 all preallocted %d\n", count);
-	}
+	printk(KERN_DEBUG "1 found new irq_desc for irq %d and pri will be irq %d\n", desc->irq, desc_pri->irq);
 
 	return desc;
 }
@@ -285,7 +272,7 @@
 
 	return NULL;
 }
-struct irq_desc *__irq_to_desc(unsigned int irq)
+struct irq_desc *irq_to_desc_alloc(unsigned int irq)
 {
 	return irq_to_desc(irq);
 }
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index c0b4d4d..6df4921 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -31,7 +31,7 @@
  */
 void synchronize_irq(unsigned int irq)
 {
-	struct irq_desc *desc = __irq_to_desc(irq);
+	struct irq_desc *desc = irq_to_desc(irq);
 	unsigned int status;
 
 	if (!desc)
@@ -145,7 +145,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc)
 		return;
 
@@ -174,7 +174,7 @@
 {
 	struct irq_desc *desc;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc)
 		return;
 
@@ -218,7 +218,7 @@
 	struct irq_desc *desc;
 	unsigned long flags;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc)
 		return;
 
@@ -296,7 +296,7 @@
 	struct irq_desc *desc;
 	struct irqaction *action;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc)
 		return 0;
 
@@ -366,7 +366,7 @@
 	int shared = 0;
 	int ret;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc)
 		return -EINVAL;
 
@@ -527,7 +527,7 @@
 
 	WARN_ON(in_interrupt());
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc)
 		return;
 
@@ -644,7 +644,7 @@
 	if ((irqflags & IRQF_SHARED) && !dev_id)
 		return -EINVAL;
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (!desc)
 		return -EINVAL;