Index: sys/kern/subr_smr.c
===================================================================
--- sys/kern/subr_smr.c
+++ sys/kern/subr_smr.c
@@ -275,7 +275,7 @@
 		c = zpcpu_get_cpu(smr, i);
 		c_seq = SMR_SEQ_INVALID;
 		for (;;) {
-			c_seq = atomic_load_int(&c->c_seq);
+			c_seq = atomic_load_acq_int(&c->c_seq);
 			if (c_seq == SMR_SEQ_INVALID)
 				break;
 
@@ -323,15 +323,21 @@
 		if (c_seq != SMR_SEQ_INVALID && SMR_SEQ_GT(rd_seq, c_seq))
 			rd_seq = c_seq;
 	}
+	/* Same semantic for reads of c->c_seq above as in smr_enter(). */
+	atomic_thread_fence_acq();
 
 	/*
 	 * Advance the rd_seq as long as we observed the most recent one.
 	 */
 	s_rd_seq = atomic_load_int(&s->s_rd_seq);
-	do {
+	for (;;) {
 		if (SMR_SEQ_LEQ(rd_seq, s_rd_seq))
 			break;
-	} while (atomic_fcmpset_int(&s->s_rd_seq, &s_rd_seq, rd_seq) == 0);
+		if (atomic_fcmpset_int(&s->s_rd_seq, &s_rd_seq, rd_seq) != 0) {
+			atomic_thread_fence_rel();
+			break;
+		}
+	}
 
 out:
 	critical_exit();
Index: tools/uma/smrstress/smrstress.c
===================================================================
--- tools/uma/smrstress/smrstress.c
+++ tools/uma/smrstress/smrstress.c
@@ -84,7 +84,7 @@
 	/* Wait for the writer to exit. */
 	while (smrs_completed == 0) {
 		smr_enter(smrs_smr);
-		cur = (void *)atomic_load_ptr(&smrs_current);
+		cur = (void *)atomic_load_acq_ptr(&smrs_current);
 		if (cur->generation == -1)
 			smrs_error(cur, "read early: Use after free!\n");
 		atomic_add_int(&cur->count, 1);
@@ -107,6 +107,7 @@
 
 	for (i = 0; i < smrs_iterations; i++) {
 		cur = uma_zalloc_smr(smrs_zone, M_WAITOK);
+		atomic_thread_fence_rel();
 		cur = (void *)atomic_swap_ptr(&smrs_current, (uintptr_t)cur);
 		uma_zfree_smr(smrs_zone, cur);
 	}