Index: uvm_pmemrange.c
===================================================================
RCS file: /cvs/src/sys/uvm/uvm_pmemrange.c,v
retrieving revision 1.46
diff -u -p -r1.46 uvm_pmemrange.c
--- uvm_pmemrange.c	27 Jun 2015 21:25:55 -0000	1.46
+++ uvm_pmemrange.c	2 Jul 2015 05:03:38 -0000
@@ -2001,8 +2001,10 @@ uvm_pagezero_thread(void *arg)
 		uvm_unlock_fpageq();
 
 		TAILQ_FOREACH(pg, &pgl, pageq) {
+			KASSERT(ISSET(pg->pg_flags, PQ_FREE));
 			uvm_pagezero(pg);
 			atomic_setbits_int(&pg->pg_flags, PG_ZERO);
+			KASSERT(ISSET(pg->pg_flags, PQ_FREE));
 		}
 
 		uvm_lock_fpageq();