[PATCH 4.9 30/96] MIPS: irq: Allocate accurate order pages for irq stack

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Liu Xiang <liu.xiang6@xxxxxxxxxx>

commit 72faa7a773ca59336f3c889e878de81445c5a85c upstream.

The irq_pages is the number of pages for irq stack, but not the
order which is needed by __get_free_pages().
We can use get_order() to calculate the accurate order.

Signed-off-by: Liu Xiang <liu.xiang6@xxxxxxxxxx>
Signed-off-by: Paul Burton <paul.burton@xxxxxxxx>
Fixes: fe8bd18ffea5 ("MIPS: Introduce irq_stack")
Cc: linux-mips@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # v4.11+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/mips/kernel/irq.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/mips/kernel/irq.c
+++ b/arch/mips/kernel/irq.c
@@ -52,6 +52,7 @@ asmlinkage void spurious_interrupt(void)
 void __init init_IRQ(void)
 {
 	int i;
+	unsigned int order = get_order(IRQ_STACK_SIZE);
 
 	for (i = 0; i < NR_IRQS; i++)
 		irq_set_noprobe(i);
@@ -62,8 +63,7 @@ void __init init_IRQ(void)
 	arch_init_irq();
 
 	for_each_possible_cpu(i) {
-		int irq_pages = IRQ_STACK_SIZE / PAGE_SIZE;
-		void *s = (void *)__get_free_pages(GFP_KERNEL, irq_pages);
+		void *s = (void *)__get_free_pages(GFP_KERNEL, order);
 
 		irq_stack[i] = s;
 		pr_debug("CPU%d IRQ stack at 0x%p - 0x%p\n", i,