Index: kern/kern_switch.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_switch.c,v
retrieving revision 1.97
diff -u -r1.97 kern_switch.c
--- kern/kern_switch.c	5 Oct 2004 22:03:10 -0000	1.97
+++ kern/kern_switch.c	12 Oct 2004 14:14:59 -0000
@@ -449,6 +449,10 @@
 	KASSERT(td->td_critnest != 0,
 	    ("critical_exit: td_critnest == 0"));
 	if (td->td_critnest == 1) {
+		if (PCPU_GET(wakeproc0)) {
+			PCPU_SET(wakeproc0, 0);
+			wakeup(&proc0);
+		}
 #ifdef PREEMPTION
 		mtx_assert(&sched_lock, MA_NOTOWNED);
 		if (td->td_pflags & TDP_OWEPREEMPT) {
Index: kern/kern_synch.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_synch.c,v
retrieving revision 1.262
diff -u -r1.262 kern_synch.c
--- kern/kern_synch.c	5 Oct 2004 18:51:11 -0000	1.262
+++ kern/kern_synch.c	12 Oct 2004 14:14:59 -0000
@@ -390,13 +390,12 @@
 	if ((p->p_sflag & PS_INMEM) == 0) {
 		if ((p->p_sflag & PS_SWAPPINGIN) == 0) {
 			p->p_sflag |= PS_SWAPINREQ;
-#ifndef SMP
 			/*
-			 * XXX: Disabled on SMP due to a LOR between
-			 * sched_lock and the sleepqueue chain locks.
+			 * Schedule a wakeup of the swapper when the
+			 * CPU leaves its current critical section so
+			 * that 'td' can be swapped on as soon as possible.
 			 */
-			wakeup(&proc0);
-#endif
+			PCPU_SET(wakeproc0, 1);
 		}
 	} else
 		sched_wakeup(td);
Index: sys/pcpu.h
===================================================================
RCS file: /home/ncvs/src/sys/sys/pcpu.h,v
retrieving revision 1.13
diff -u -r1.13 pcpu.h
--- sys/pcpu.h	27 Mar 2004 18:21:24 -0000	1.13
+++ sys/pcpu.h	12 Oct 2004 14:15:04 -0000
@@ -65,6 +65,7 @@
 	u_int		pc_cpuid;		/* This cpu number */
 	cpumask_t	pc_cpumask;		/* This cpu mask */
 	cpumask_t	pc_other_cpus;		/* Mask of all other cpus */
+	int		pc_wakeproc0;
 	SLIST_ENTRY(pcpu) pc_allcpu;
 	struct lock_list_entry *pc_spinlocks;
 #ifdef KTR_PERCPU