diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index 1fee839b9895..778c0545b7ca 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -2281,6 +2281,7 @@ vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
 		 * above.)
 		 */
 		entry->eflags |= MAP_ENTRY_IN_TRANSITION;
+		entry->wiring_thread = curthread;
 		/*
 		 * Check the map for holes in the specified region.
 		 * If VM_MAP_WIRE_HOLESOK was specified, skip this check.
@@ -2313,8 +2314,24 @@ done:
 		else
 			KASSERT(result, ("vm_map_unwire: lookup failed"));
 	}
-	entry = first_entry;
-	while (entry != &map->header && entry->start < end) {
+	for (entry = first_entry; entry != &map->header && entry->start < end;
+	    entry = entry->next) {
+		/*
+		 * If VM_MAP_WIRE_HOLESOK was specified, an empty
+		 * space in the unwired region could have been mapped
+		 * while the map lock was dropped for draining
+		 * MAP_ENTRY_IN_TRANSITION.  Moreover, another thread
+		 * could be simultaneously wiring this new mapping
+		 * entry.  Detect these cases and skip any entries
+		 * marked as in transition by us.
+		 */
+		if ((entry->eflags & MAP_ENTRY_IN_TRANSITION) == 0 ||
+		    entry->wiring_thread != curthread) {
+			KASSERT((flags & VM_MAP_WIRE_HOLESOK) != 0,
+			    ("vm_map_unwire: !HOLESOK and new/changed entry"));
+			continue;
+		}
+
 		if (rv == KERN_SUCCESS && (!user_unwire ||
 		    (entry->eflags & MAP_ENTRY_USER_WIRED))) {
 			if (user_unwire)
@@ -2330,15 +2347,15 @@ done:
 				    OBJ_FICTITIOUS) != 0);
 			}
 		}
-		KASSERT(entry->eflags & MAP_ENTRY_IN_TRANSITION,
-			("vm_map_unwire: in-transition flag missing"));
+		KASSERT((entry->eflags & MAP_ENTRY_IN_TRANSITION) != 0,
+		    ("vm_map_unwire: in-transition flag missing"));
 		entry->eflags &= ~MAP_ENTRY_IN_TRANSITION;
+		entry->wiring_thread = NULL;
 		if (entry->eflags & MAP_ENTRY_NEEDS_WAKEUP) {
 			entry->eflags &= ~MAP_ENTRY_NEEDS_WAKEUP;
 			need_wakeup = TRUE;
 		}
 		vm_map_simplify_entry(map, entry);
-		entry = entry->next;
 	}
 	vm_map_unlock(map);
 	if (need_wakeup)
@@ -2432,6 +2449,7 @@ vm_map_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
 		 * above.)
 		 */
 		entry->eflags |= MAP_ENTRY_IN_TRANSITION;
+		entry->wiring_thread = curthread;
 		if ((entry->protection & (VM_PROT_READ | VM_PROT_EXECUTE)) == 0
 		    || (entry->protection & prot) != prot) {
 			entry->eflags |= MAP_ENTRY_WIRE_SKIPPED;
@@ -2523,10 +2541,27 @@ done:
 		else
 			KASSERT(result, ("vm_map_wire: lookup failed"));
 	}
-	entry = first_entry;
-	while (entry != &map->header && entry->start < end) {
+	for (entry = first_entry; entry != &map->header && entry->start < end;
+	    entry = entry->next) {
 		if ((entry->eflags & MAP_ENTRY_WIRE_SKIPPED) != 0)
 			goto next_entry_done;
+
+		/*
+		 * If VM_MAP_WIRE_HOLESOK was specified, an empty
+		 * space in the unwired region could have been mapped
+		 * while the map lock was dropped for faulting in the
+		 * pages or draining MAP_ENTRY_IN_TRANSITION.
+		 * Moreover, another thread could be simultaneously
+		 * wiring this new mapping entry.  Detect these cases
+		 * and skip any entries marked as in transition by us.
+		 */
+		if ((entry->eflags & MAP_ENTRY_IN_TRANSITION) == 0 ||
+		    entry->wiring_thread != curthread) {
+			KASSERT((flags & VM_MAP_WIRE_HOLESOK) != 0,
+			    ("vm_map_wire: !HOLESOK and new/changed entry"));
+			continue;
+		}
+
 		if (rv == KERN_SUCCESS) {
 			if (user_wire)
 				entry->eflags |= MAP_ENTRY_USER_WIRED;
@@ -2551,15 +2586,18 @@ done:
 			}
 		}
 	next_entry_done:
-		KASSERT(entry->eflags & MAP_ENTRY_IN_TRANSITION,
-			("vm_map_wire: in-transition flag missing"));
-		entry->eflags &= ~(MAP_ENTRY_IN_TRANSITION|MAP_ENTRY_WIRE_SKIPPED);
+		KASSERT((entry->eflags & MAP_ENTRY_IN_TRANSITION) != 0,
+		    ("vm_map_wire: in-transition flag missing %p", entry));
+		KASSERT(entry->wiring_thread == curthread,
+		    ("vm_map_wire: alien wire %p", entry));
+		entry->eflags &= ~(MAP_ENTRY_IN_TRANSITION |
+		    MAP_ENTRY_WIRE_SKIPPED);
+		entry->wiring_thread = NULL;
 		if (entry->eflags & MAP_ENTRY_NEEDS_WAKEUP) {
 			entry->eflags &= ~MAP_ENTRY_NEEDS_WAKEUP;
 			need_wakeup = TRUE;
 		}
 		vm_map_simplify_entry(map, entry);
-		entry = entry->next;
 	}
 	vm_map_unlock(map);
 	if (need_wakeup)
@@ -3193,6 +3231,7 @@ vmspace_fork(struct vmspace *vm1, vm_ooffset_t *fork_charge)
 			*new_entry = *old_entry;
 			new_entry->eflags &= ~(MAP_ENTRY_USER_WIRED |
 			    MAP_ENTRY_IN_TRANSITION);
+			new_entry->wiring_thread = NULL;
 			new_entry->wired_count = 0;
 			if (new_entry->eflags & MAP_ENTRY_VN_WRITECNT) {
 				vnode_pager_update_writecount(object,
@@ -3227,6 +3266,7 @@ vmspace_fork(struct vmspace *vm1, vm_ooffset_t *fork_charge)
 			 */
 			new_entry->eflags &= ~(MAP_ENTRY_USER_WIRED |
 			    MAP_ENTRY_IN_TRANSITION | MAP_ENTRY_VN_WRITECNT);
+			new_entry->wiring_thread = NULL;
 			new_entry->wired_count = 0;
 			new_entry->object.vm_object = NULL;
 			new_entry->cred = NULL;
diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h
index 135b555d5aa2..a73691d8890d 100644
--- a/sys/vm/vm_map.h
+++ b/sys/vm/vm_map.h
@@ -116,6 +116,7 @@ struct vm_map_entry {
 	int wired_count;		/* can be paged if = 0 */
 	vm_pindex_t next_read;		/* index of the next sequential read */
 	struct ucred *cred;		/* tmp storage for creator ref */
+	struct thread *wiring_thread;
 };
 
 #define MAP_ENTRY_NOSYNC		0x0001