diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index f503ee6571..7735434206 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -2196,6 +2196,7 @@ dump_block_stats(spa_t *spa)
 	 * it's not part of any space map) is a double allocation,
 	 * reference to a freed block, or an unclaimed log block.
 	 */
+	bzero(&zcb, sizeof(zdb_cb_t));
 	zdb_leak_init(spa, &zcb);
 
 	/*
diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index 1290ef2646..6d4e6742d2 100644
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -5275,6 +5275,11 @@ ztest_run(ztest_shared_t *zs)
 	}
 
 	kernel_fini();
+
+	list_destroy(&zcl.zcl_callbacks);
+	mutex_destroy(&zcl.zcl_callbacks_lock);
+	rw_destroy(&zs->zs_name_lock);
+	mutex_destroy(&zs->zs_vdev_lock);
 }
 
 static void
@@ -5345,12 +5350,8 @@ ztest_freeze(ztest_shared_t *zs)
 	spa_close(spa, FTAG);
 	kernel_fini();
 
-	list_destroy(&zcl.zcl_callbacks);
-
-	(void) mutex_destroy(&zcl.zcl_callbacks_lock);
-
-	(void) rw_destroy(&zs->zs_name_lock);
-	(void) mutex_destroy(&zs->zs_vdev_lock);
+	rw_destroy(&zs->zs_name_lock);
+	mutex_destroy(&zs->zs_vdev_lock);
 }
 
 void
@@ -5453,6 +5454,7 @@ main(int argc, char **argv)
 
 	ztest_random_fd = open("/dev/urandom", O_RDONLY);
 
+	dprintf_setup(&argc, argv);
 	process_options(argc, argv);
 
 	/* Override location of zpool.cache */
diff --git a/lib/libzpool/include/sys/zfs_context.h b/lib/libzpool/include/sys/zfs_context.h
index 5649d4762e..837ddce6ec 100644
--- a/lib/libzpool/include/sys/zfs_context.h
+++ b/lib/libzpool/include/sys/zfs_context.h
@@ -504,6 +504,7 @@ typedef struct callb_cpr {
 #define	zone_dataset_visible(x, y)	(1)
 #define	INGLOBALZONE(z)			(1)
 
+extern char *kmem_vasprintf(const char *fmt, va_list adx);
 extern char *kmem_asprintf(const char *fmt, ...);
 #define	strfree(str) kmem_free((str), strlen(str)+1)
 
diff --git a/lib/libzpool/kernel.c b/lib/libzpool/kernel.c
index c7bac38b8f..9d5b1c9547 100644
--- a/lib/libzpool/kernel.c
+++ b/lib/libzpool/kernel.c
@@ -1120,25 +1120,27 @@ ksiddomain_rele(ksiddomain_t *ksid)
 	umem_free(ksid, sizeof (ksiddomain_t));
 }
 
-/*
- * Do not change the length of the returned string; it must be freed
- * with strfree().
- */
+char *
+kmem_vasprintf(const char *fmt, va_list adx)
+{
+	char *buf = NULL;
+	va_list adx_copy;
+
+	va_copy(adx_copy, adx);
+	VERIFY(vasprintf(&buf, fmt, adx_copy) != -1);
+	va_end(adx_copy);
+
+	return (buf);
+}
+
 char *
 kmem_asprintf(const char *fmt, ...)
 {
-	int size;
+	char *buf = NULL;
 	va_list adx;
-	char *buf;
 
 	va_start(adx, fmt);
-	size = vsnprintf(NULL, 0, fmt, adx) + 1;
-	va_end(adx);
-
-	buf = kmem_alloc(size, KM_SLEEP);
-
-	va_start(adx, fmt);
-	size = vsnprintf(buf, size, fmt, adx);
+	VERIFY(vasprintf(&buf, fmt, adx) != -1);
 	va_end(adx);
 
 	return (buf);
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index 51f912c142..8e0e910e08 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -727,7 +727,7 @@ dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 		else
 			dmu_buf_will_dirty(db, tx);
 
-		bcopy(buf, (char *)db->db_data + bufoff, tocpy);
+		(void) memcpy((char *)db->db_data + bufoff, buf, tocpy);
 
 		if (tocpy == db->db_size)
 			dmu_buf_fill_done(db, tx);
diff --git a/module/zfs/spa_history.c b/module/zfs/spa_history.c
index e5ceed9ff6..243f2b4ab3 100644
--- a/module/zfs/spa_history.c
+++ b/module/zfs/spa_history.c
@@ -432,6 +432,7 @@ log_internal(history_internal_events_t event, spa_t *spa,
     dmu_tx_t *tx, const char *fmt, va_list adx)
 {
 	history_arg_t *ha;
+	va_list adx_copy;
 
 	/*
 	 * If this is part of creating a pool, not everything is
@@ -441,7 +442,9 @@ log_internal(history_internal_events_t event, spa_t *spa,
 		return;
 
 	ha = kmem_alloc(sizeof (history_arg_t), KM_SLEEP);
-	ha->ha_history_str = kmem_asprintf(fmt, adx);
+	va_copy(adx_copy, adx);
+	ha->ha_history_str = kmem_vasprintf(fmt, adx_copy);
+	va_end(adx_copy);
 	ha->ha_log_type = LOG_INTERNAL;
 	ha->ha_event = event;
 	ha->ha_zone = NULL;
diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index 228fc14fff..90d98fb4d7 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -234,13 +234,8 @@ kmem_cache_t *spa_buffer_pool;
 int spa_mode_global;
 
 #ifdef ZFS_DEBUG
-#if defined(_KERNEL) && defined(HAVE_SPL)
-/* All filtering done by the SPL */
-int zfs_flags = ~0;
-#else
 /* Everything except dprintf is on by default in debug builds */
 int zfs_flags = ~ZFS_DEBUG_DPRINTF;
-#endif
 #else
 int zfs_flags = 0;
 #endif
diff --git a/module/zpios/zpios.c b/module/zpios/zpios.c
index ff2db3b39b..9aa3b5c1bb 100644
--- a/module/zpios/zpios.c
+++ b/module/zpios/zpios.c
@@ -443,7 +443,7 @@ zpios_dmu_write(run_args_t *run_args, objset_t *os, uint64_t object,
 {
 	struct dmu_tx *tx;
 	int rc, how = TXG_WAIT;
-	int flags = 0;
+//	int flags = 0;
 
 	if (run_args->flags & DMU_WRITE_NOWAIT)
 		how = TXG_NOWAIT;
@@ -467,10 +467,10 @@ zpios_dmu_write(run_args_t *run_args, objset_t *os, uint64_t object,
 		break;
 	}
 
-	if (run_args->flags & DMU_WRITE_ZC)
-		flags |= DMU_WRITE_ZEROCOPY;
+//	if (run_args->flags & DMU_WRITE_ZC)
+//		flags |= DMU_WRITE_ZEROCOPY;
 
-	dmu_write_impl(os, object, offset, size, buf, tx, flags);
+	dmu_write(os, object, offset, size, buf, tx);
 	dmu_tx_commit(tx);
 
 	return 0;
@@ -482,8 +482,8 @@ zpios_dmu_read(run_args_t *run_args, objset_t *os, uint64_t object,
 {
 	int flags = 0;
 
-	if (run_args->flags & DMU_READ_ZC)
-		flags |= DMU_READ_ZEROCOPY;
+//	if (run_args->flags & DMU_READ_ZC)
+//		flags |= DMU_READ_ZEROCOPY;
 
 	if (run_args->flags & DMU_READ_NOPF)
 		flags |= DMU_READ_NO_PREFETCH;