Index: head/sys/vm/vm_page.c
===================================================================
--- head/sys/vm/vm_page.c
+++ head/sys/vm/vm_page.c
@@ -3546,12 +3546,15 @@
 			    m, i, (uintmax_t)*p));
 	}
 #endif
-	if ((m->oflags & VPO_UNMANAGED) == 0)
+	if ((m->oflags & VPO_UNMANAGED) == 0) {
 		KASSERT(!pmap_page_is_mapped(m),
 		    ("vm_page_free_prep: freeing mapped page %p", m));
-	else
+		KASSERT((m->aflags & (PGA_EXECUTABLE | PGA_WRITEABLE)) == 0,
+		    ("vm_page_free_prep: mapping flags set in page %p", m));
+	} else {
 		KASSERT(m->queue == PQ_NONE,
 		    ("vm_page_free_prep: unmanaged page %p is queued", m));
+	}
 	VM_CNT_INC(v_tfree);
 
 	if (vm_page_sbusied(m))