diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index f7c0d2d..9cbe61f 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -1396,13 +1396,15 @@ pmap_qenter(vm_offset_t sva, vm_page_t *ma, int count)
 		    PAGE_SIZE);
 }
 
+void vm_check_stack_unmap(vm_offset_t sva, int count);
+void pmap_qremove_stack(vm_offset_t sva, int count);
 /*
  * This routine tears out page mappings from the
  * kernel -- it is meant only for temporary mappings.
  * Note: SMP coherent.  Uses a ranged shootdown IPI.
  */
 void
-pmap_qremove(vm_offset_t sva, int count)
+pmap_qremove_stack(vm_offset_t sva, int count)
 {
 	vm_offset_t va;
 
@@ -1414,6 +1416,14 @@ pmap_qremove(vm_offset_t sva, int count)
 	pmap_invalidate_range(kernel_pmap, sva, va);
 }
 
+void
+pmap_qremove(vm_offset_t sva, int count)
+{
+
+	vm_check_stack_unmap(sva, count);
+	pmap_qremove_stack(sva, count);
+}
+
 /***************************************************
  * Page table page management routines.....
  ***************************************************/
diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c
index c552cb7..0b455e8 100644
--- a/sys/vm/vm_glue.c
+++ b/sys/vm/vm_glue.c
@@ -349,6 +349,30 @@ SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0,
 #define KSTACK_MAX_PAGES 32
 #endif
 
+static struct stack_va {
+	vm_offset_t va;
+	int count;
+} stack_vas[2048];
+
+void vm_check_stack_unmap(vm_offset_t sva, int count);
+void pmap_qremove_stack(vm_offset_t sva, int count);
+
+void
+vm_check_stack_unmap(vm_offset_t sva, int count)
+{
+	struct stack_va *v;
+	int i;
+
+	for (i = 0; i < sizeof(stack_vas) / sizeof(struct stack_va); i++) {
+		v = &stack_vas[i];
+		if (v->va == 0)
+			continue;
+		if ((sva >= v->va && sva < v->va + v->count * PAGE_SIZE) ||
+		    (sva <= v->va && sva + count * PAGE_SIZE < v->va))
+			panic("pmap_qremove stack");
+	}
+}
+
 /*
  * Create the kernel stack (including pcb for i386) for a new thread.
  * This routine directly affects the fork perf for a process and
@@ -411,7 +435,7 @@ vm_thread_new(struct thread *td, int pages)
 
 	atomic_add_int(&kstacks, 1);
 	if (KSTACK_GUARD_PAGES != 0) {
-		pmap_qremove(ks, KSTACK_GUARD_PAGES);
+		pmap_qremove_stack(ks, KSTACK_GUARD_PAGES);
 		ks += KSTACK_GUARD_PAGES * PAGE_SIZE;
 	}
 	td->td_kstack_obj = ksobj;
@@ -436,6 +460,21 @@ vm_thread_new(struct thread *td, int pages)
 		m->valid = VM_PAGE_BITS_ALL;
 	}
 	VM_OBJECT_UNLOCK(ksobj);
+	mtx_lock(&kstack_cache_mtx);
+	for (i = 0; i < sizeof(stack_vas) / sizeof(struct stack_va); i++) {
+		struct stack_va *v;
+
+		v = &stack_vas[i];
+		if (v->va == 0) {
+			v->va = ks;
+			v->count = pages;
+			break;
+		}
+	}
+	mtx_unlock(&kstack_cache_mtx);
+	if (i == sizeof(stack_vas) / sizeof(struct stack_va))
+		panic("stack_vas too small");
+	
 	pmap_qenter(ks, ma, pages);
 	return (1);
 }
@@ -447,7 +486,21 @@ vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages)
 	int i;
 
 	atomic_add_int(&kstacks, -1);
-	pmap_qremove(ks, pages);
+	pmap_qremove_stack(ks, pages);
+	mtx_lock(&kstack_cache_mtx);
+	for (i = 0; i < sizeof(stack_vas) / sizeof(struct stack_va); i++) {
+		struct stack_va *v;
+
+		v = &stack_vas[i];
+		if (v->va == ks) {
+			v->va = 0;
+			break;
+		}
+	}
+	mtx_unlock(&kstack_cache_mtx);
+	if (i == sizeof(stack_vas) / sizeof(struct stack_va))
+		panic("stack prot not found");
+
 	VM_OBJECT_LOCK(ksobj);
 	for (i = 0; i < pages; i++) {
 		m = vm_page_lookup(ksobj, i);
@@ -536,7 +589,7 @@ vm_thread_swapout(struct thread *td)
 	cpu_thread_swapout(td);
 	pages = td->td_kstack_pages;
 	ksobj = td->td_kstack_obj;
-	pmap_qremove(td->td_kstack, pages);
+	pmap_qremove_stack(td->td_kstack, pages);
 	VM_OBJECT_LOCK(ksobj);
 	for (i = 0; i < pages; i++) {
 		m = vm_page_lookup(ksobj, i);