diff -urN 2.3.40pre1/kernel/timer.c 2.3.40pre1-timer/kernel/timer.c
--- 2.3.40pre1/kernel/timer.c	Tue Dec 14 15:48:51 1999
+++ 2.3.40pre1-timer/kernel/timer.c	Thu Jan 13 19:19:11 2000
@@ -138,6 +138,15 @@
 		/* can happen if you add a timer with expires == jiffies,
 		 * or you set a timer to go off in the past
 		 */
+		if ((signed long) idx < -50)
+			/* Nobody should set a timer so insanely in the past or
+			   waiting so many timer interrupts between reading
+			   jiffies and calling the timer code. The timer code
+			   is completly robust against this condition but
+			   a printk may let us know about bugs in the
+			   caller we might not notice otherwise. */
+			printk(KERN_WARNING
+			       "timer inserted in the past, idx = %ld\n", idx);
 		insert_timer(timer, tv1.vec, tv1.index);
 	} else if (idx <= 0xffffffffUL) {
 		int i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
@@ -222,10 +231,31 @@
         tv->index = (tv->index + 1) & TVN_MASK;
 }
 
+/* defer current timers to the next pass */
+static inline void cascade_current_timers(void)
+{
+	struct timer_list * timer;
+	int index = tv1.index;
+
+	timer = tv1.vec[index];
+	tv1.index = (tv1.index + 1) & TVR_MASK;
+
+	while (timer)
+	{
+		struct timer_list *tmp = timer;
+		timer = timer->next;
+		insert_timer(tmp, tv1.vec, tv1.index);
+	}
+	tv1.vec[index] = NULL;
+}
+
 static inline void run_timer_list(void)
 {
+	long passes;
+
 	spin_lock_irq(&timerlist_lock);
-	while ((long)(jiffies - timer_jiffies) >= 0) {
+	passes = jiffies - timer_jiffies;
+	while (passes-- >= 0) {
 		struct timer_list *timer;
 		if (!tv1.index) {
 			int n = 1;
@@ -233,17 +263,20 @@
 				cascade_timers(tvecs[n]);
 			} while (tvecs[n]->index == 1 && ++n < NOOF_TVECS);
 		}
-		while ((timer = tv1.vec[tv1.index])) {
+		timer = tv1.vec[tv1.index];
+		tv1.vec[tv1.index] = 0;
+		while (timer) {
 			void (*fn)(unsigned long) = timer->function;
 			unsigned long data = timer->data;
-			detach_timer(timer);
-			timer->next = timer->prev = NULL;
+			struct timer_list * tmp = timer;
+			timer = timer->next;
+			tmp->next = tmp->prev = NULL;
 			spin_unlock_irq(&timerlist_lock);
 			fn(data);
 			spin_lock_irq(&timerlist_lock);
 		}
 		++timer_jiffies; 
-		tv1.index = (tv1.index + 1) & TVR_MASK;
+		cascade_current_timers();
 	}
 	spin_unlock_irq(&timerlist_lock);
 }