Index: sys/kern/kern_ktr.c
===================================================================
--- sys/kern/kern_ktr.c	(revision 229932)
+++ sys/kern/kern_ktr.c	(working copy)
@@ -256,6 +256,8 @@
 	cpu = KTR_CPU;
 	if (!CPU_ISSET(cpu, &ktr_cpumask))
 		return;
+	if (strcmp(curthread->td_name, "fsck_ufs"))
+		return;
 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
 	td = curthread;
 	if (td->td_pflags & TDP_INKTR)
Index: sys/vm/vm_radix.c
===================================================================
--- sys/vm/vm_radix.c	(revision 229932)
+++ sys/vm/vm_radix.c	(working copy)
@@ -218,6 +218,8 @@
 
 	c = (uintptr_t)child;
 
+	CTR3(KTR_FLO, "match: child %p, color %d, ret %jx",
+	    child, color, (uintmax_t)(c & ~VM_RADIX_FLAGS));
 	if ((c & color) == 0)
 		return (NULL);
 	return ((void *)(c & ~VM_RADIX_FLAGS));
@@ -430,10 +432,16 @@
 	int level;
 
 	start = *startp;
+	CTR3(KTR_FLO, "leaf: tree %p, start %ju, end %ju",
+	    rtree, (uintmax_t)*startp, (uintmax_t)end);
 restart:
 	level = vm_radix_height(rtree, &rnode);
+	CTR4(KTR_FLO, "leaf: tree %p, start %ju, end %ju, level %d",
+	    rtree, (uintmax_t)*startp, (uintmax_t)end, level);
 	if (start > VM_RADIX_MAX(level) || (end && start >= end)) {
 		rnode = NULL;
+		CTR3(KTR_FLO, "leaf: exit start %ju, end %ju, level %d",
+		    (uintmax_t)start, (uintmax_t)end, level);
 		goto out;
 	}
 	/*
@@ -442,12 +450,15 @@
 	 */
 	for (level--; level; level--) {
 		slot = vm_radix_slot(start, level);
-		CTR6(KTR_VM,
+		CTR6(KTR_FLO,
 	"leaf: tree %p, index %ju, level %d, slot %d, rnode %p, child %p",
 		    rtree, (uintmax_t)start, level, slot, rnode,
 		    (rnode != NULL) ? rnode->rn_child[slot] : NULL);
 		if (rnode->rn_child[slot] != NULL) {
 			rnode = rnode->rn_child[slot];
+			CTR4(KTR_FLO,
+		    "leaf: continuing start %ju, end %ju, slot %d, rnode %p",
+			    (uintmax_t)start, (uintmax_t)end, slot, rnode);
 			continue;
 		}
 		/*
@@ -460,22 +471,33 @@
 		start &= ~VM_RADIX_MAX(level);
 		start += inc;
 		slot++;
-		CTR5(KTR_VM,
+		CTR5(KTR_FLO,
 		    "leaf: start %ju end %ju inc %d mask 0x%lX slot %d",
 		    (uintmax_t)start, (uintmax_t)end, inc,
 		    ~VM_RADIX_MAX(level), slot);
 		for (; slot < VM_RADIX_COUNT; slot++, start += inc) {
 			if (end != 0 && start >= end) {
 				rnode = NULL;
+				CTR3(KTR_FLO,
+				    "leaf: exit start %ju, end %ju, slot %d",
+		    		    (uintmax_t)start, (uintmax_t)end, slot);
 				goto out;
 			}
 			if (rnode->rn_child[slot]) {
 				rnode = rnode->rn_child[slot];
+				CTR4(KTR_FLO,
+			    "leaf: exit start %ju, end %ju, slot %d, rnode %p",
+		    		    (uintmax_t)start, (uintmax_t)end, slot,
+				    rnode);
 				break;
 			}
 		}
-		if (slot == VM_RADIX_COUNT)
+		if (slot == VM_RADIX_COUNT) {
+			CTR4(KTR_FLO,
+			    "leaf: exit start %ju, end %ju, slot %d, level %d",
+			    (uintmax_t)start, (uintmax_t)end, slot, level);
 			goto restart;
+		}
 	}
 
 out:
@@ -499,28 +521,49 @@
 	int slot;
 	int outidx;
 
-	CTR3(KTR_VM, "lookupn: tree %p, start %ju, end %ju",
+	CTR3(KTR_FLO, "lookupn: tree %p, start %ju, end %ju",
 	    rtree, (uintmax_t)start, (uintmax_t)end);
-	if (rtree->rt_root == 0)
+	if (rtree->rt_root == 0) {
+		CTR0(KTR_FLO, "lookupn: return with rt_root 0");
 		return (0);
+	}
 	outidx = 0;
 	while ((rnode = vm_radix_leaf(rtree, &start, end)) != NULL) {
 		slot = vm_radix_slot(start, 0);
+		CTR2(KTR_FLO, "lookupn: rnode %p with slot %d found on leaf",
+		    rnode, slot);
 		for (; slot < VM_RADIX_COUNT; slot++, start++) {
-			if (end != 0 && start >= end)
+			if (end != 0 && start >= end) {
+				CTR3(KTR_FLO,
+			     "lookupn: exit start %ju, end %ju, slot %d",
+				    (uintmax_t)start, (uintmax_t)end, slot);
 				goto out;
+			}
 			val = vm_radix_match(rnode->rn_child[slot], color);
-			if (val == NULL)
+			if (val == NULL) {
+				CTR3(KTR_FLO,
+			     "lookupn: continuing start %ju, end %ju, slot %d",
+				    (uintmax_t)start, (uintmax_t)end, slot);
 				continue;
-			CTR4(KTR_VM,
+			}
+			CTR4(KTR_FLO,
 			    "lookupn: tree %p index %ju slot %d found child %p",
 			    rtree, (uintmax_t)start, slot, val);
 			out[outidx] = val;
-			if (++outidx == cnt)
+			if (++outidx == cnt) {
+				CTR4(KTR_FLO,
+		     "lookupn: exit start %ju, end %ju, slot %d, outidx %d",
+				    (uintmax_t)start, (uintmax_t)end, slot,
+				    outidx);
 				goto out;
+			}
 		}
-		if (end != 0 && start >= end)
+		if (end != 0 && start >= end) {
+			CTR4(KTR_FLO,
+		    "lookupn: exit start %ju, end %ju, slot %d, outidx %d",
+			    (uintmax_t)start, (uintmax_t)end, slot, outidx);
 			break;
+		}
 	}
 out:
 	*next = start;
@@ -535,19 +578,33 @@
 	void *val;
 	int slot;
 
-	if (rtree->rt_root == 0)
+	CTR3(KTR_FLO, "foreach: tree %p, start %ju, end %ju",
+	    rtree, (uintmax_t)start, (uintmax_t)end);
+	if (rtree->rt_root == 0) {
+		CTR0(KTR_FLO, "foreach: return with rt_root 0");
 		return;
+	}
 	while ((rnode = vm_radix_leaf(rtree, &start, end)) != NULL) {
 		slot = vm_radix_slot(start, 0);
+		CTR2(KTR_FLO, "foreach: rnode %p with slot %d found on leaf",
+		    rnode, slot);
 		for (; slot < VM_RADIX_COUNT; slot++, start++) {
-			if (end != 0 && start >= end)
+			if (end != 0 && start >= end) {
+				CTR3(KTR_FLO,
+			     "foreach: exit start %ju, end %ju, slot %d",
+				    (uintmax_t)start, (uintmax_t)end, slot);
 				return;
+			}
 			val = vm_radix_match(rnode->rn_child[slot], color);
 			if (val)
 				iter(val);
 		}
-		if (end != 0 && start >= end)
+		if (end != 0 && start >= end) {
+			CTR3(KTR_FLO,
+		    "foreach: exit start %ju, end %ju, slot %d",
+			    (uintmax_t)start, (uintmax_t)end, slot);
 			return;
+		}
 	}
 }
 
Index: sys/sys/ktr.h
===================================================================
--- sys/sys/ktr.h	(revision 229932)
+++ sys/sys/ktr.h	(working copy)
@@ -75,6 +75,7 @@
 #define	KTR_INET6	0x10000000		/* IPv6 stack */
 #define	KTR_SCHED	0x20000000		/* Machine parsed sched info. */
 #define	KTR_BUF		0x40000000		/* Buffer cache */
+#define	KTR_FLO		0x80000000		/* Test */
 #define	KTR_ALL		0x7fffffff
 
 /* Trace classes to compile in */