diff -urN linux-2.5.12/mm/page-writeback.c linux/mm/page-writeback.c
--- linux-2.5.12/mm/page-writeback.c	Wed May  1 08:40:14 2002
+++ linux/mm/page-writeback.c	Wed May  1 10:56:24 2002
@@ -20,6 +20,7 @@
 #include <linux/writeback.h>
 #include <linux/init.h>
 #include <linux/sysrq.h>
+#include <linux/percpu.h>
 
 /*
  * Memory thresholds, in percentages
@@ -102,15 +103,11 @@
  */
 void balance_dirty_pages_ratelimited(struct address_space *mapping)
 {
-	static struct rate_limit_struct {
-		int count;
-	} ____cacheline_aligned ratelimits[NR_CPUS];
-	int cpu;
+	static int __per_cpu_data ratelimits;
 
 	preempt_disable();
-	cpu = smp_processor_id();
-	if (ratelimits[cpu].count++ >= 32) {
-		ratelimits[cpu].count = 0;
+	if (this_cpu(ratelimits)++ >= 32) {
+		this_cpu(ratelimits) = 0;
 		preempt_enable();
 		balance_dirty_pages(mapping);
 		return;