--- uma_dbg.c.orig	Mon Nov  7 23:05:09 2005
+++ uma_dbg.c	Tue Nov  8 17:37:24 2005
@@ -41,6 +41,8 @@
 #include <sys/lock.h>
 #include <sys/mutex.h>
 #include <sys/malloc.h>
+#include <sys/callout.h>
+#include <sys/kdb.h>
 
 #include <vm/vm.h>
 #include <vm/vm_object.h>
@@ -86,8 +88,33 @@
 {
 	int cnt;
 	u_int32_t *p;
+	struct callout *c;
+	struct callout_tailq *bucket;
+	int i;
 
 	cnt = size / sizeof(uma_junk);
+
+	mtx_lock_spin(&callout_lock);
+ 
+	for (i = 0; i < callwheelsize; ++i) {
+		bucket = &callwheel[i];
+		for (c = TAILQ_FIRST(bucket); c != NULL;
+		     c = TAILQ_NEXT(c, c_links.tqe)) {
+			int c2 = (int)c;
+			int mem2 = (int)mem;
+			if ((u_int32_t)c == uma_junk) {
+				kdb_enter("trash_dtor: uma_junk found in a "\
+					  "callwheel element");
+				break;
+			}
+			if (c2 >= mem2 && c2 < mem2 + size) {
+				kdb_enter("trash_dtor: found invalid "\
+					  "callwhel element");
+			}
+		}
+	}
+
+	mtx_unlock_spin(&callout_lock);
 
 	for (p = mem; cnt > 0; cnt--, p++)
 		*p = uma_junk;