diff --git a/sys/kern/kern_lock.c b/sys/kern/kern_lock.c
index 690cbec3fbf6..68944bf9fa07 100644
--- a/sys/kern/kern_lock.c
+++ b/sys/kern/kern_lock.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: kern_lock.c,v 1.33 2000/07/14 07:16:44 thorpej Exp $	*/
+/*	$NetBSD: kern_lock.c,v 1.34 2000/08/07 21:55:23 thorpej Exp $	*/
 
 /*-
  * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
@@ -934,4 +934,27 @@ simple_lock_freecheck(void *start, void *end)
 	SLOCK_LIST_UNLOCK();
 	splx(s);
 }
+
+void
+simple_lock_switchcheck(void)
+{
+	struct simplelock *alp;
+	cpuid_t cpu_id = cpu_number();
+	int s;
+
+	s = splhigh();
+	SLOCK_LIST_LOCK();
+	for (alp = TAILQ_FIRST(&simplelock_list); alp != NULL;
+	     alp = TAILQ_NEXT(alp, list)) {
+		if (alp->lock_holder == cpu_id) {
+			lock_printf("switching with held simple_lock %p "
+			    "CPU %lu %s:%s\n",
+			    alp, alp->lock_holder, alp->lock_file,
+			    alp->lock_line);
+			SLOCK_DEBUGGER();
+		}
+	}
+	SLOCK_LIST_UNLOCK();
+	splx(s);
+}
 #endif /* LOCKDEBUG */ /* } */
diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index dc914873087e..4a07612812ab 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: kern_synch.c,v 1.80 2000/08/02 20:21:36 nathanw Exp $	*/
+/*	$NetBSD: kern_synch.c,v 1.81 2000/08/07 21:55:23 thorpej Exp $	*/
 
 /*-
  * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
@@ -764,15 +764,10 @@ mi_switch(struct proc *p)
 
 	spc = &p->p_cpu->ci_schedstate;
 
-#ifdef DEBUG
-	if (p->p_simple_locks) {
-		printf("p->p_simple_locks %d\n", p->p_simple_locks);
 #ifdef LOCKDEBUG
-		simple_lock_dump();
-#endif
-		panic("sleep: holding simple lock");
-	}
+	simple_lock_switchcheck();
 #endif
+
 	/*
 	 * Compute the amount of time during which the current
 	 * process was running, and add that to its total so far.
diff --git a/sys/sys/lock.h b/sys/sys/lock.h
index 1547037f1316..2ab7b3945a00 100644
--- a/sys/sys/lock.h
+++ b/sys/sys/lock.h
@@ -1,7 +1,7 @@
-/*	$NetBSD: lock.h,v 1.32 2000/07/14 07:16:45 thorpej Exp $	*/
+/*	$NetBSD: lock.h,v 1.33 2000/08/07 21:55:22 thorpej Exp $	*/
 
 /*-
- * Copyright (c) 1999 The NetBSD Foundation, Inc.
+ * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
@@ -297,6 +297,7 @@ void	_simple_unlock(__volatile struct simplelock *, const char *, int);
 void	simple_lock_init(struct simplelock *);
 void	simple_lock_dump(void);
 void	simple_lock_freecheck(void *, void *);
+void	simple_lock_switchcheck(void);
 #elif defined(MULTIPROCESSOR)
 #define	simple_lock_init(alp)	__cpu_simple_lock_init(&(alp)->lock_data)
 #define	simple_lock(alp)	__cpu_simple_lock(&(alp)->lock_data)
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index db016097e7a6..5c4c9c1e650c 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: proc.h,v 1.98 2000/06/08 05:50:40 thorpej Exp $	*/
+/*	$NetBSD: proc.h,v 1.99 2000/08/07 21:55:22 thorpej Exp $	*/
 
 /*-
  * Copyright (c) 1986, 1989, 1991, 1993
@@ -179,8 +179,7 @@ struct	proc {
 
 	struct	vnode *p_textvp;	/* Vnode of executable. */
 
-	short   p_locks;		/* DEBUG: lockmgr count of held locks */
-	short   p_simple_locks;		/* DEBUG: count of held simple locks */
+	int	p_locks;		/* DEBUG: lockmgr count of held locks */
 
 	int	p_holdcnt;		/* If non-zero, don't swap. */
 	struct	emul *p_emul;		/* Emulation information */