diff -ruN linux-2.4.21-pre5/fs/proc/array.c linux-2.4.21-pre5.up-opt/fs/proc/array.c
--- linux-2.4.21-pre5/fs/proc/array.c	2002-08-07 00:52:23.000000000 +0200
+++ linux-2.4.21-pre5.up-opt/fs/proc/array.c	2003-02-27 13:02:18.000000000 +0100
@@ -390,7 +390,7 @@
 		task->nswap,
 		task->cnswap,
 		task->exit_signal,
-		task->processor);
+		task_cpu(task));
 	if(mm)
 		mmput(mm);
 	return res;
diff -ruN linux-2.4.21-pre5/include/linux/sched.h linux-2.4.21-pre5.up-opt/include/linux/sched.h
--- linux-2.4.21-pre5/include/linux/sched.h	2003-02-27 12:58:59.000000000 +0100
+++ linux-2.4.21-pre5.up-opt/include/linux/sched.h	2003-02-27 13:02:18.000000000 +0100
@@ -566,11 +566,39 @@
 	return p;
 }
 
+/*
+ * Wrappers for p->processor access. No-op on UP.
+ */
+#ifdef CONFIG_SMP
+
+static inline int task_cpu(const struct task_struct *p)
+{
+	return p->processor;
+}
+
+static inline void set_task_cpu(struct task_struct *p, int cpu)
+{
+	p->processor = cpu;
+}
+
+#else
+
+static inline int task_cpu(const struct task_struct *p)
+{
+	return 0;
+}
+
+static inline void set_task_cpu(struct task_struct *p, int cpu)
+{
+}
+
+#endif /* CONFIG_SMP */
+
 #define task_has_cpu(tsk) ((tsk)->cpus_runnable != ~0UL)
 
 static inline void task_set_cpu(struct task_struct *tsk, unsigned int cpu)
 {
-	tsk->processor = cpu;
+	set_task_cpu(tsk, cpu);
 	tsk->cpus_runnable = 1UL << cpu;
 }
 
diff -ruN linux-2.4.21-pre5/init/main.c linux-2.4.21-pre5.up-opt/init/main.c
--- linux-2.4.21-pre5/init/main.c	2002-08-07 00:52:26.000000000 +0200
+++ linux-2.4.21-pre5.up-opt/init/main.c	2003-02-27 13:02:18.000000000 +0100
@@ -310,7 +310,7 @@
 	/* Get other processors into their bootup holding patterns. */
 	smp_boot_cpus();
 	wait_init_idle = cpu_online_map;
-	clear_bit(current->processor, &wait_init_idle); /* Don't wait on me! */
+	clear_bit(task_cpu(current), &wait_init_idle); /* Don't wait on me! */
 
 	smp_threads_ready=1;
 	smp_commence();
diff -ruN linux-2.4.21-pre5/kernel/fork.c linux-2.4.21-pre5.up-opt/kernel/fork.c
--- linux-2.4.21-pre5/kernel/fork.c	2002-11-30 17:12:32.000000000 +0100
+++ linux-2.4.21-pre5.up-opt/kernel/fork.c	2003-02-27 13:02:18.000000000 +0100
@@ -666,7 +666,7 @@
 	{
 		int i;
 		p->cpus_runnable = ~0UL;
-		p->processor = current->processor;
+		set_task_cpu(p, task_cpu(current));
 		/* ?? should we just memset this ?? */
 		for(i = 0; i < smp_num_cpus; i++)
 			p->per_cpu_utime[i] = p->per_cpu_stime[i] = 0;
diff -ruN linux-2.4.21-pre5/kernel/sched.c linux-2.4.21-pre5.up-opt/kernel/sched.c
--- linux-2.4.21-pre5/kernel/sched.c	2003-02-27 12:58:59.000000000 +0100
+++ linux-2.4.21-pre5.up-opt/kernel/sched.c	2003-02-27 13:02:18.000000000 +0100
@@ -172,7 +172,7 @@
 #ifdef CONFIG_SMP
 		/* Give a largish advantage to the same processor...   */
 		/* (this is equivalent to penalizing other processors) */
-		if (p->processor == this_cpu)
+		if (task_cpu(p) == this_cpu)
 			weight += PROC_CHANGE_PENALTY;
 #endif
 
@@ -221,7 +221,7 @@
 	 * shortcut if the woken up task's last CPU is
 	 * idle now.
 	 */
-	best_cpu = p->processor;
+	best_cpu = task_cpu(p);
 	if (can_schedule(p, best_cpu)) {
 		tsk = idle_task(best_cpu);
 		if (cpu_curr(best_cpu) == tsk) {
@@ -295,12 +295,12 @@
 	tsk = target_tsk;
 	if (tsk) {
 		if (oldest_idle != -1ULL) {
-			best_cpu = tsk->processor;
+			best_cpu = task_cpu(tsk);
 			goto send_now_idle;
 		}
 		tsk->need_resched = 1;
-		if (tsk->processor != this_cpu)
-			smp_send_reschedule(tsk->processor);
+		if (task_cpu(tsk) != this_cpu)
+			smp_send_reschedule(task_cpu(tsk));
 	}
 	return;
 		
@@ -557,7 +557,7 @@
 	BUG_ON(!current->active_mm);
 need_resched_back:
 	prev = current;
-	this_cpu = prev->processor;
+	this_cpu = task_cpu(prev);
 
 	if (unlikely(in_interrupt())) {
 		printk("Scheduling in interrupt\n");
@@ -1364,7 +1364,7 @@
 	}
 	sched_data->curr = current;
 	sched_data->last_schedule = get_cycles();
-	clear_bit(current->processor, &wait_init_idle);
+	clear_bit(task_cpu(current), &wait_init_idle);
 }
 
 extern void init_timervecs (void);
@@ -1378,7 +1378,7 @@
 	int cpu = smp_processor_id();
 	int nr;
 
-	init_task.processor = cpu;
+	set_task_cpu(&init_task, cpu);
 
 	for(nr = 0; nr < PIDHASH_SZ; nr++)
 		pidhash[nr] = NULL;
diff -ruN linux-2.4.21-pre5/kernel/signal.c linux-2.4.21-pre5.up-opt/kernel/signal.c
--- linux-2.4.21-pre5/kernel/signal.c	2003-02-27 12:58:59.000000000 +0100
+++ linux-2.4.21-pre5.up-opt/kernel/signal.c	2003-02-27 13:02:18.000000000 +0100
@@ -508,8 +508,8 @@
 	 * other than doing an extra (lightweight) IPI interrupt.
 	 */
 	spin_lock(&runqueue_lock);
-	if (task_has_cpu(t) && t->processor != smp_processor_id())
-		smp_send_reschedule(t->processor);
+	if (task_has_cpu(t) && task_cpu(t) != smp_processor_id())
+		smp_send_reschedule(task_cpu(t));
 	spin_unlock(&runqueue_lock);
 #endif /* CONFIG_SMP */