diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index b5cee5b3bd8d..930342d2e421 100644
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -57,6 +57,9 @@
  *     the transaction group number is less than the current, open txg.
  *     If you add a new test, please do this if applicable.
  *
+ * (7) Threads are created with a reduced stack size, for sanity checking.
+ *     Therefore, it's important not to allocate huge buffers on the stack.
+ *
  * When run with no arguments, ztest runs for about five minutes and
  * produces no output if successful.  To get a little bit of information,
  * specify -V.  To get more information, specify -VV, and so on.
@@ -168,8 +171,8 @@ typedef enum {
 typedef struct rll {
 	void		*rll_writer;
 	int		rll_readers;
-	mutex_t		rll_lock;
-	cond_t		rll_cv;
+	kmutex_t	rll_lock;
+	kcondvar_t	rll_cv;
 } rll_t;
 
 typedef struct rl {
@@ -206,7 +209,7 @@ typedef struct ztest_ds {
 	uint64_t	zd_seq;
 	ztest_od_t	*zd_od;		/* debugging aid */
 	char		zd_name[MAXNAMELEN];
-	mutex_t		zd_dirobj_lock;
+	kmutex_t	zd_dirobj_lock;
 	rll_t		zd_object_lock[ZTEST_OBJECT_LOCKS];
 	rll_t		zd_range_lock[ZTEST_RANGE_LOCKS];
 } ztest_ds_t;
@@ -299,8 +302,8 @@ ztest_info_t ztest_info[] = {
  * The callbacks are ordered by txg number.
  */
 typedef struct ztest_cb_list {
-	mutex_t	zcl_callbacks_lock;
-	list_t	zcl_callbacks;
+	kmutex_t	zcl_callbacks_lock;
+	list_t		zcl_callbacks;
 } ztest_cb_list_t;
 
 /*
@@ -319,8 +322,8 @@ typedef struct ztest_shared {
 	uint64_t	zs_vdev_aux;
 	uint64_t	zs_alloc;
 	uint64_t	zs_space;
-	mutex_t		zs_vdev_lock;
-	rwlock_t	zs_name_lock;
+	kmutex_t	zs_vdev_lock;
+	krwlock_t	zs_name_lock;
 	ztest_info_t	zs_info[ZTEST_FUNCS];
 	uint64_t	zs_splits;
 	uint64_t	zs_mirrors;
@@ -892,8 +895,8 @@ ztest_rll_init(rll_t *rll)
 {
 	rll->rll_writer = NULL;
 	rll->rll_readers = 0;
-	VERIFY(_mutex_init(&rll->rll_lock, USYNC_THREAD, NULL) == 0);
-	VERIFY(cond_init(&rll->rll_cv, USYNC_THREAD, NULL) == 0);
+	mutex_init(&rll->rll_lock, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&rll->rll_cv, NULL, CV_DEFAULT, NULL);
 }
 
 static void
@@ -901,32 +904,32 @@ ztest_rll_destroy(rll_t *rll)
 {
 	ASSERT(rll->rll_writer == NULL);
 	ASSERT(rll->rll_readers == 0);
-	VERIFY(_mutex_destroy(&rll->rll_lock) == 0);
-	VERIFY(cond_destroy(&rll->rll_cv) == 0);
+	mutex_destroy(&rll->rll_lock);
+	cv_destroy(&rll->rll_cv);
 }
 
 static void
 ztest_rll_lock(rll_t *rll, rl_type_t type)
 {
-	VERIFY(mutex_lock(&rll->rll_lock) == 0);
+	mutex_enter(&rll->rll_lock);
 
 	if (type == RL_READER) {
 		while (rll->rll_writer != NULL)
-			(void) cond_wait(&rll->rll_cv, &rll->rll_lock);
+			(void) cv_wait(&rll->rll_cv, &rll->rll_lock);
 		rll->rll_readers++;
 	} else {
 		while (rll->rll_writer != NULL || rll->rll_readers)
-			(void) cond_wait(&rll->rll_cv, &rll->rll_lock);
+			(void) cv_wait(&rll->rll_cv, &rll->rll_lock);
 		rll->rll_writer = curthread;
 	}
 
-	VERIFY(mutex_unlock(&rll->rll_lock) == 0);
+	mutex_exit(&rll->rll_lock);
 }
 
 static void
 ztest_rll_unlock(rll_t *rll)
 {
-	VERIFY(mutex_lock(&rll->rll_lock) == 0);
+	mutex_enter(&rll->rll_lock);
 
 	if (rll->rll_writer) {
 		ASSERT(rll->rll_readers == 0);
@@ -938,9 +941,9 @@ ztest_rll_unlock(rll_t *rll)
 	}
 
 	if (rll->rll_writer == NULL && rll->rll_readers == 0)
-		VERIFY(cond_broadcast(&rll->rll_cv) == 0);
+		cv_broadcast(&rll->rll_cv);
 
-	VERIFY(mutex_unlock(&rll->rll_lock) == 0);
+	mutex_exit(&rll->rll_lock);
 }
 
 static void
@@ -997,7 +1000,7 @@ ztest_zd_init(ztest_ds_t *zd, objset_t *os)
 	dmu_objset_name(os, zd->zd_name);
 	int l;
 
-	VERIFY(_mutex_init(&zd->zd_dirobj_lock, USYNC_THREAD, NULL) == 0);
+	mutex_init(&zd->zd_dirobj_lock, NULL, MUTEX_DEFAULT, NULL);
 
 	for (l = 0; l < ZTEST_OBJECT_LOCKS; l++)
 		ztest_rll_init(&zd->zd_object_lock[l]);
@@ -1011,7 +1014,7 @@ ztest_zd_fini(ztest_ds_t *zd)
 {
 	int l;
 
-	VERIFY(_mutex_destroy(&zd->zd_dirobj_lock) == 0);
+	mutex_destroy(&zd->zd_dirobj_lock);
 
 	for (l = 0; l < ZTEST_OBJECT_LOCKS; l++)
 		ztest_rll_destroy(&zd->zd_object_lock[l]);
@@ -1754,7 +1757,7 @@ ztest_lookup(ztest_ds_t *zd, ztest_od_t *od, int count)
 	int error;
 	int i;
 
-	ASSERT(_mutex_held(&zd->zd_dirobj_lock));
+	ASSERT(mutex_held(&zd->zd_dirobj_lock));
 
 	for (i = 0; i < count; i++, od++) {
 		od->od_object = 0;
@@ -1795,7 +1798,7 @@ ztest_create(ztest_ds_t *zd, ztest_od_t *od, int count)
 	int missing = 0;
 	int i;
 
-	ASSERT(_mutex_held(&zd->zd_dirobj_lock));
+	ASSERT(mutex_held(&zd->zd_dirobj_lock));
 
 	for (i = 0; i < count; i++, od++) {
 		if (missing) {
@@ -1841,7 +1844,7 @@ ztest_remove(ztest_ds_t *zd, ztest_od_t *od, int count)
 	int error;
 	int i;
 
-	ASSERT(_mutex_held(&zd->zd_dirobj_lock));
+	ASSERT(mutex_held(&zd->zd_dirobj_lock));
 
 	od += count - 1;
 
@@ -2057,13 +2060,13 @@ ztest_object_init(ztest_ds_t *zd, ztest_od_t *od, size_t size, boolean_t remove)
 	int count = size / sizeof (*od);
 	int rv = 0;
 
-	VERIFY(mutex_lock(&zd->zd_dirobj_lock) == 0);
+	mutex_enter(&zd->zd_dirobj_lock);
 	if ((ztest_lookup(zd, od, count) != 0 || remove) &&
 	    (ztest_remove(zd, od, count) != 0 ||
 	    ztest_create(zd, od, count) != 0))
 		rv = -1;
 	zd->zd_od = od;
-	VERIFY(mutex_unlock(&zd->zd_dirobj_lock) == 0);
+	mutex_exit(&zd->zd_dirobj_lock);
 
 	return (rv);
 }
@@ -2119,7 +2122,7 @@ ztest_spa_create_destroy(ztest_ds_t *zd, uint64_t id)
 	 * Attempt to create an existing pool.  It shouldn't matter
 	 * what's in the nvroot; we should fail with EEXIST.
 	 */
-	(void) rw_rdlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_READER);
 	nvroot = make_vdev_root("/dev/bogus", NULL, 0, 0, 0, 0, 0, 1);
 	VERIFY3U(EEXIST, ==, spa_create(zs->zs_pool, nvroot, NULL, NULL, NULL));
 	nvlist_free(nvroot);
@@ -2127,7 +2130,7 @@ ztest_spa_create_destroy(ztest_ds_t *zd, uint64_t id)
 	VERIFY3U(EBUSY, ==, spa_destroy(zs->zs_pool));
 	spa_close(spa, FTAG);
 
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 }
 
 static vdev_t *
@@ -2181,7 +2184,7 @@ ztest_vdev_add_remove(ztest_ds_t *zd, uint64_t id)
 	nvlist_t *nvroot;
 	int error;
 
-	VERIFY(mutex_lock(&zs->zs_vdev_lock) == 0);
+	mutex_enter(&zs->zs_vdev_lock);
 	leaves = MAX(zs->zs_mirrors + zs->zs_splits, 1) * zopt_raidz;
 
 	spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
@@ -2207,9 +2210,9 @@ ztest_vdev_add_remove(ztest_ds_t *zd, uint64_t id)
 		 * dmu_objset_destroy() to fail with EBUSY thus
 		 * leaving the dataset in an inconsistent state.
 		 */
-		VERIFY(rw_wrlock(&ztest_shared->zs_name_lock) == 0);
+		rw_enter(&ztest_shared->zs_name_lock, RW_WRITER);
 		error = spa_vdev_remove(spa, guid, B_FALSE);
-		VERIFY(rw_unlock(&ztest_shared->zs_name_lock) == 0);
+		rw_exit(&ztest_shared->zs_name_lock);
 
 		if (error && error != EEXIST)
 			fatal(0, "spa_vdev_remove() = %d", error);
@@ -2231,7 +2234,7 @@ ztest_vdev_add_remove(ztest_ds_t *zd, uint64_t id)
 			fatal(0, "spa_vdev_add() = %d", error);
 	}
 
-	VERIFY(mutex_unlock(&ztest_shared->zs_vdev_lock) == 0);
+	mutex_exit(&ztest_shared->zs_vdev_lock);
 }
 
 /*
@@ -2257,7 +2260,7 @@ ztest_vdev_aux_add_remove(ztest_ds_t *zd, uint64_t id)
 		aux = ZPOOL_CONFIG_L2CACHE;
 	}
 
-	VERIFY(mutex_lock(&zs->zs_vdev_lock) == 0);
+	mutex_enter(&zs->zs_vdev_lock);
 
 	spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
 
@@ -2313,7 +2316,7 @@ ztest_vdev_aux_add_remove(ztest_ds_t *zd, uint64_t id)
 			fatal(0, "spa_vdev_remove(%llu) = %d", guid, error);
 	}
 
-	VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+	mutex_exit(&zs->zs_vdev_lock);
 }
 
 /*
@@ -2330,11 +2333,11 @@ ztest_split_pool(ztest_ds_t *zd, uint64_t id)
 	uint_t c, children, schildren = 0, lastlogid = 0;
 	int error = 0;
 
-	VERIFY(mutex_lock(&zs->zs_vdev_lock) == 0);
+	mutex_enter(&zs->zs_vdev_lock);
 
 	/* ensure we have a useable config; mirrors of raidz aren't supported */
 	if (zs->zs_mirrors < 3 || zopt_raidz > 1) {
-		VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+		mutex_exit(&zs->zs_vdev_lock);
 		return;
 	}
 
@@ -2393,9 +2396,9 @@ ztest_split_pool(ztest_ds_t *zd, uint64_t id)
 
 	spa_config_exit(spa, SCL_VDEV, FTAG);
 
-	(void) rw_wrlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_WRITER);
 	error = spa_vdev_split_mirror(spa, "splitp", config, NULL, B_FALSE);
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 
 	nvlist_free(config);
 
@@ -2408,7 +2411,7 @@ ztest_split_pool(ztest_ds_t *zd, uint64_t id)
 		++zs->zs_splits;
 		--zs->zs_mirrors;
 	}
-	VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+	mutex_exit(&zs->zs_vdev_lock);
 
 }
 
@@ -2437,7 +2440,7 @@ ztest_vdev_attach_detach(ztest_ds_t *zd, uint64_t id)
 	int oldvd_is_log;
 	int error, expected_error;
 
-	VERIFY(mutex_lock(&zs->zs_vdev_lock) == 0);
+	mutex_enter(&zs->zs_vdev_lock);
 	leaves = MAX(zs->zs_mirrors, 1) * zopt_raidz;
 
 	spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
@@ -2498,7 +2501,7 @@ ztest_vdev_attach_detach(ztest_ds_t *zd, uint64_t id)
 		if (error != 0 && error != ENODEV && error != EBUSY &&
 		    error != ENOTSUP)
 			fatal(0, "detach (%s) returned %d", oldpath, error);
-		VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+		mutex_exit(&zs->zs_vdev_lock);
 		return;
 	}
 
@@ -2591,7 +2594,7 @@ ztest_vdev_attach_detach(ztest_ds_t *zd, uint64_t id)
 		    (longlong_t)newsize, replacing, error, expected_error);
 	}
 
-	VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+	mutex_exit(&zs->zs_vdev_lock);
 }
 
 /*
@@ -2722,7 +2725,7 @@ ztest_vdev_LUN_growth(ztest_ds_t *zd, uint64_t id)
 	uint64_t top;
 	uint64_t old_class_space, new_class_space, old_ms_count, new_ms_count;
 
-	VERIFY(mutex_lock(&zs->zs_vdev_lock) == 0);
+	mutex_enter(&zs->zs_vdev_lock);
 	spa_config_enter(spa, SCL_STATE, spa, RW_READER);
 
 	top = ztest_random_vdev_top(spa, B_TRUE);
@@ -2750,7 +2753,7 @@ ztest_vdev_LUN_growth(ztest_ds_t *zd, uint64_t id)
 	if (tvd->vdev_state != VDEV_STATE_HEALTHY ||
 	    psize == 0 || psize >= 4 * zopt_vdev_size) {
 		spa_config_exit(spa, SCL_STATE, spa);
-		VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+		mutex_exit(&zs->zs_vdev_lock);
 		return;
 	}
 	ASSERT(psize > 0);
@@ -2775,7 +2778,7 @@ ztest_vdev_LUN_growth(ztest_ds_t *zd, uint64_t id)
 			    "the vdev configuration changed.\n");
 		}
 		spa_config_exit(spa, SCL_STATE, spa);
-		VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+		mutex_exit(&zs->zs_vdev_lock);
 		return;
 	}
 
@@ -2809,7 +2812,7 @@ ztest_vdev_LUN_growth(ztest_ds_t *zd, uint64_t id)
 			    "intervening vdev offline or remove.\n");
 		}
 		spa_config_exit(spa, SCL_STATE, spa);
-		VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+		mutex_exit(&zs->zs_vdev_lock);
 		return;
 	}
 
@@ -2837,7 +2840,7 @@ ztest_vdev_LUN_growth(ztest_ds_t *zd, uint64_t id)
 	}
 
 	spa_config_exit(spa, SCL_STATE, spa);
-	VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+	mutex_exit(&zs->zs_vdev_lock);
 }
 
 /*
@@ -2945,7 +2948,7 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 	zilog_t *zilog;
 	int i;
 
-	(void) rw_rdlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_READER);
 
 	(void) snprintf(name, MAXNAMELEN, "%s/temp_%llu",
 	    zs->zs_pool, (u_longlong_t)id);
@@ -2983,7 +2986,7 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 	if (error) {
 		if (error == ENOSPC) {
 			ztest_record_enospc(FTAG);
-			(void) rw_unlock(&zs->zs_name_lock);
+			(void) rw_exit(&zs->zs_name_lock);
 			return;
 		}
 		fatal(0, "dmu_objset_create(%s) = %d", name, error);
@@ -3032,7 +3035,7 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 	dmu_objset_disown(os, FTAG);
 	ztest_zd_fini(&zdtmp);
 
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 }
 
 /*
@@ -3043,10 +3046,10 @@ ztest_dmu_snapshot_create_destroy(ztest_ds_t *zd, uint64_t id)
 {
 	ztest_shared_t *zs = ztest_shared;
 
-	(void) rw_rdlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_READER);
 	(void) ztest_snapshot_destroy(zd->zd_name, id);
 	(void) ztest_snapshot_create(zd->zd_name, id);
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 }
 
 /*
@@ -3107,7 +3110,7 @@ ztest_dsl_dataset_promote_busy(ztest_ds_t *zd, uint64_t id)
 	char *osname = zd->zd_name;
 	int error;
 
-	(void) rw_rdlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_READER);
 
 	ztest_dsl_dataset_cleanup(osname, id);
 
@@ -3192,7 +3195,7 @@ ztest_dsl_dataset_promote_busy(ztest_ds_t *zd, uint64_t id)
 out:
 	ztest_dsl_dataset_cleanup(osname, id);
 
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 }
 
 /*
@@ -4111,7 +4114,7 @@ ztest_commit_callback(void *arg, int error)
 	ASSERT(data->zcd_added);
 	ASSERT3U(data->zcd_txg, !=, 0);
 
-	(void) mutex_lock(&zcl.zcl_callbacks_lock);
+	(void) mutex_enter(&zcl.zcl_callbacks_lock);
 
 	/* See if this cb was called more quickly */
 	if ((synced_txg - data->zcd_txg) < zc_min_txg_delay)
@@ -4120,7 +4123,7 @@ ztest_commit_callback(void *arg, int error)
 	/* Remove our callback from the list */
 	list_remove(&zcl.zcl_callbacks, data);
 
-	(void) mutex_unlock(&zcl.zcl_callbacks_lock);
+	(void) mutex_exit(&zcl.zcl_callbacks_lock);
 
 	umem_free(data, sizeof (ztest_cb_data_t));
 }
@@ -4135,6 +4138,7 @@ ztest_create_cb_data(objset_t *os, uint64_t txg)
 
 	cb_data->zcd_txg = txg;
 	cb_data->zcd_spa = dmu_objset_spa(os);
+	list_link_init(&cb_data->zcd_node);
 
 	return (cb_data);
 }
@@ -4214,7 +4218,7 @@ ztest_dmu_commit_callbacks(ztest_ds_t *zd, uint64_t id)
 
 	dmu_write(os, od[0].od_object, 0, sizeof (uint64_t), &txg, tx);
 
-	(void) mutex_lock(&zcl.zcl_callbacks_lock);
+	(void) mutex_enter(&zcl.zcl_callbacks_lock);
 
 	/*
 	 * Since commit callbacks don't have any ordering requirement and since
@@ -4263,7 +4267,7 @@ ztest_dmu_commit_callbacks(ztest_ds_t *zd, uint64_t id)
 
 	zc_cb_counter += 3;
 
-	(void) mutex_unlock(&zcl.zcl_callbacks_lock);
+	(void) mutex_exit(&zcl.zcl_callbacks_lock);
 
 	dmu_tx_commit(tx);
 }
@@ -4281,13 +4285,13 @@ ztest_dsl_prop_get_set(ztest_ds_t *zd, uint64_t id)
 	ztest_shared_t *zs = ztest_shared;
 	int p;
 
-	(void) rw_rdlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_READER);
 
 	for (p = 0; p < sizeof (proplist) / sizeof (proplist[0]); p++)
 		(void) ztest_dsl_prop_set_uint64(zd->zd_name, proplist[p],
 		    ztest_random_dsl_prop(proplist[p]), (int)ztest_random(2));
 
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 }
 
 /* ARGSUSED */
@@ -4297,7 +4301,7 @@ ztest_spa_prop_get_set(ztest_ds_t *zd, uint64_t id)
 	ztest_shared_t *zs = ztest_shared;
 	nvlist_t *props = NULL;
 
-	(void) rw_rdlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_READER);
 
 	(void) ztest_spa_prop_set_uint64(zs, ZPOOL_PROP_DEDUPDITTO,
 	    ZIO_DEDUPDITTO_MIN + ztest_random(ZIO_DEDUPDITTO_MIN));
@@ -4309,7 +4313,7 @@ ztest_spa_prop_get_set(ztest_ds_t *zd, uint64_t id)
 
 	nvlist_free(props);
 
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 }
 
 /*
@@ -4327,14 +4331,14 @@ ztest_dmu_snapshot_hold(ztest_ds_t *zd, uint64_t id)
 	char tag[100];
 	char osname[MAXNAMELEN];
 
-	(void) rw_rdlock(&ztest_shared->zs_name_lock);
+	(void) rw_enter(&ztest_shared->zs_name_lock, RW_READER);
 
 	dmu_objset_name(os, osname);
 
-	(void) snprintf(snapname, 100, "sh1_%llu", id);
+	(void) snprintf(snapname, 100, "sh1_%llu", (u_longlong_t)id);
 	(void) snprintf(fullname, 100, "%s@%s", osname, snapname);
-	(void) snprintf(clonename, 100, "%s/ch1_%llu", osname, id);
-	(void) snprintf(tag, 100, "%tag_%llu", id);
+	(void) snprintf(clonename, 100, "%s/ch1_%llu",osname,(u_longlong_t)id);
+	(void) snprintf(tag, 100, "tag_%llu", (u_longlong_t)id);
 
 	/*
 	 * Clean up from any previous run.
@@ -4424,7 +4428,7 @@ ztest_dmu_snapshot_hold(ztest_ds_t *zd, uint64_t id)
 	VERIFY(dmu_objset_hold(fullname, FTAG, &origin) == ENOENT);
 
 out:
-	(void) rw_unlock(&ztest_shared->zs_name_lock);
+	(void) rw_exit(&ztest_shared->zs_name_lock);
 }
 
 /*
@@ -4452,11 +4456,11 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 	uint64_t guid0 = 0;
 	boolean_t islog = B_FALSE;
 
-	VERIFY(mutex_lock(&zs->zs_vdev_lock) == 0);
+	mutex_enter(&zs->zs_vdev_lock);
 	maxfaults = MAXFAULTS();
 	leaves = MAX(zs->zs_mirrors, 1) * zopt_raidz;
 	mirror_save = zs->zs_mirrors;
-	VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+	mutex_exit(&zs->zs_vdev_lock);
 
 	ASSERT(leaves >= 1);
 
@@ -4550,12 +4554,13 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 			 * leaving the dataset in an inconsistent state.
 			 */
 			if (islog)
-				(void) rw_wrlock(&ztest_shared->zs_name_lock);
+				(void) rw_enter(&ztest_shared->zs_name_lock,
+				    RW_WRITER);
 
 			VERIFY(vdev_offline(spa, guid0, flags) != EBUSY);
 
 			if (islog)
-				(void) rw_unlock(&ztest_shared->zs_name_lock);
+				(void) rw_exit(&ztest_shared->zs_name_lock);
 		} else {
 			(void) vdev_online(spa, guid0, 0, NULL);
 		}
@@ -4582,9 +4587,9 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 		if (offset >= fsize)
 			continue;
 
-		VERIFY(mutex_lock(&zs->zs_vdev_lock) == 0);
+		mutex_enter(&zs->zs_vdev_lock);
 		if (mirror_save != zs->zs_mirrors) {
-			VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+			mutex_exit(&zs->zs_vdev_lock);
 			(void) close(fd);
 			return;
 		}
@@ -4593,7 +4598,7 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 			fatal(1, "can't inject bad word at 0x%llx in %s",
 			    offset, pathrand);
 
-		VERIFY(mutex_unlock(&zs->zs_vdev_lock) == 0);
+		mutex_exit(&zs->zs_vdev_lock);
 
 		if (zopt_verbose >= 7)
 			(void) printf("injected bad word into %s,"
@@ -4634,13 +4639,13 @@ ztest_ddt_repair(ztest_ds_t *zd, uint64_t id)
 	 * Take the name lock as writer to prevent anyone else from changing
 	 * the pool and dataset properies we need to maintain during this test.
 	 */
-	(void) rw_wrlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_WRITER);
 
 	if (ztest_dsl_prop_set_uint64(zd->zd_name, ZFS_PROP_DEDUP, checksum,
 	    B_FALSE) != 0 ||
 	    ztest_dsl_prop_set_uint64(zd->zd_name, ZFS_PROP_COPIES, 1,
 	    B_FALSE) != 0) {
-		(void) rw_unlock(&zs->zs_name_lock);
+		(void) rw_exit(&zs->zs_name_lock);
 		return;
 	}
 
@@ -4654,7 +4659,7 @@ ztest_ddt_repair(ztest_ds_t *zd, uint64_t id)
 	dmu_tx_hold_write(tx, object, 0, copies * blocksize);
 	txg = ztest_tx_assign(tx, TXG_WAIT, FTAG);
 	if (txg == 0) {
-		(void) rw_unlock(&zs->zs_name_lock);
+		(void) rw_exit(&zs->zs_name_lock);
 		return;
 	}
 
@@ -4698,7 +4703,7 @@ ztest_ddt_repair(ztest_ds_t *zd, uint64_t id)
 
 	zio_buf_free(buf, psize);
 
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 }
 
 /*
@@ -4727,7 +4732,7 @@ ztest_spa_rename(ztest_ds_t *zd, uint64_t id)
 	char *oldname, *newname;
 	spa_t *spa;
 
-	(void) rw_wrlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_WRITER);
 
 	oldname = zs->zs_pool;
 	newname = umem_alloc(strlen(oldname) + 5, UMEM_NOFAIL);
@@ -4767,7 +4772,7 @@ ztest_spa_rename(ztest_ds_t *zd, uint64_t id)
 
 	umem_free(newname, strlen(newname) + 1);
 
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 }
 
 /*
@@ -4940,23 +4945,18 @@ ztest_resume_thread(void *arg)
 			ztest_resume(spa);
 		(void) poll(NULL, 0, 100);
 	}
-	return (NULL);
-}
 
-static void *
-ztest_deadman_thread(void *arg)
-{
-	ztest_shared_t *zs = arg;
-	int grace = 300;
-	hrtime_t delta;
+	thread_exit();
 
-	delta = (zs->zs_thread_stop - zs->zs_thread_start) / NANOSEC + grace;
-
-	(void) poll(NULL, 0, (int)(1000 * delta));
+	return (NULL);
+}
 
-	fatal(0, "failed to complete within %d seconds of deadline", grace);
+#define GRACE	300
 
-	return (NULL);
+static void
+ztest_deadman_alarm(int sig)
+{
+	fatal(0, "failed to complete within %d seconds of deadline", GRACE);
 }
 
 static void
@@ -5017,6 +5017,8 @@ ztest_thread(void *arg)
 			ztest_execute(zi, id);
 	}
 
+	thread_exit();
+
 	return (NULL);
 }
 
@@ -5082,18 +5084,18 @@ ztest_dataset_open(ztest_shared_t *zs, int d)
 
 	ztest_dataset_name(name, zs->zs_pool, d);
 
-	(void) rw_rdlock(&zs->zs_name_lock);
+	(void) rw_enter(&zs->zs_name_lock, RW_READER);
 
 	error = ztest_dataset_create(name);
 	if (error == ENOSPC) {
-		(void) rw_unlock(&zs->zs_name_lock);
+		(void) rw_exit(&zs->zs_name_lock);
 		ztest_record_enospc(FTAG);
 		return (error);
 	}
 	ASSERT(error == 0 || error == EEXIST);
 
 	VERIFY3U(dmu_objset_hold(name, zd, &os), ==, 0);
-	(void) rw_unlock(&zs->zs_name_lock);
+	(void) rw_exit(&zs->zs_name_lock);
 
 	ztest_zd_init(zd, os);
 
@@ -5144,9 +5146,10 @@ ztest_dataset_close(ztest_shared_t *zs, int d)
 static void
 ztest_run(ztest_shared_t *zs)
 {
-	thread_t *tid;
+	kt_did_t *tid;
 	spa_t *spa;
-	thread_t resume_tid;
+	kthread_t *resume_thread;
+	uint64_t object;
 	int error;
 	int t, d;
 
@@ -5155,8 +5158,8 @@ ztest_run(ztest_shared_t *zs)
 	/*
 	 * Initialize parent/child shared state.
 	 */
-	VERIFY(_mutex_init(&zs->zs_vdev_lock, USYNC_THREAD, NULL) == 0);
-	VERIFY(rwlock_init(&zs->zs_name_lock, USYNC_THREAD, NULL) == 0);
+	mutex_init(&zs->zs_vdev_lock, NULL, MUTEX_DEFAULT, NULL);
+	rw_init(&zs->zs_name_lock, NULL, RW_DEFAULT, NULL);
 
 	zs->zs_thread_start = gethrtime();
 	zs->zs_thread_stop = zs->zs_thread_start + zopt_passtime * NANOSEC;
@@ -5165,7 +5168,7 @@ ztest_run(ztest_shared_t *zs)
 	if (ztest_random(100) < zopt_killrate)
 		zs->zs_thread_kill -= ztest_random(zopt_passtime * NANOSEC);
 
-	(void) _mutex_init(&zcl.zcl_callbacks_lock, USYNC_THREAD, NULL);
+	mutex_init(&zcl.zcl_callbacks_lock, NULL, MUTEX_DEFAULT, NULL);
 
 	list_create(&zcl.zcl_callbacks, sizeof (ztest_cb_data_t),
 	    offsetof(ztest_cb_data_t, zcd_node));
@@ -5192,14 +5195,14 @@ ztest_run(ztest_shared_t *zs)
 	/*
 	 * Create a thread to periodically resume suspended I/O.
 	 */
-	VERIFY(thr_create(0, 0, ztest_resume_thread, spa, THR_BOUND,
-	    &resume_tid) == 0);
+	VERIFY3P((resume_thread = thread_create(NULL, 0, ztest_resume_thread,
+	    spa, TS_RUN, NULL, 0, 0)), !=, NULL);
 
 	/*
-	 * Create a deadman thread to abort() if we hang.
+	 * Set a deadman alarm to abort() if we hang.
 	 */
-	VERIFY(thr_create(0, 0, ztest_deadman_thread, zs, THR_BOUND,
-	    NULL) == 0);
+	signal(SIGALRM, ztest_deadman_alarm);
+	alarm((zs->zs_thread_stop - zs->zs_thread_start) / NANOSEC + GRACE);
 
 	/*
 	 * Verify that we can safely inquire about about any object,
@@ -5225,7 +5228,7 @@ ztest_run(ztest_shared_t *zs)
 	}
 	zs->zs_enospc_count = 0;
 
-	tid = umem_zalloc(zopt_threads * sizeof (thread_t), UMEM_NOFAIL);
+	tid = umem_zalloc(zopt_threads * sizeof (kt_did_t), UMEM_NOFAIL);
 
 	if (zopt_verbose >= 4)
 		(void) printf("starting main threads...\n");
@@ -5234,10 +5237,14 @@ ztest_run(ztest_shared_t *zs)
 	 * Kick off all the tests that run in parallel.
 	 */
 	for (t = 0; t < zopt_threads; t++) {
+		kthread_t *thread;
+
 		if (t < zopt_datasets && ztest_dataset_open(zs, t) != 0)
 			return;
-		VERIFY(thr_create(0, 0, ztest_thread, (void *)(uintptr_t)t,
-		    THR_BOUND, &tid[t]) == 0);
+
+		VERIFY3P(thread = thread_create(NULL, 0, ztest_thread,
+		    (void *)(uintptr_t)t, TS_RUN, NULL, 0, 0), !=, NULL);
+		tid[t] = thread->t_tid;
 	}
 
 	/*
@@ -5245,7 +5252,7 @@ ztest_run(ztest_shared_t *zs)
 	 * so we don't close datasets while threads are still using them.
 	 */
 	for (t = zopt_threads - 1; t >= 0; t--) {
-		VERIFY(thr_join(tid[t], NULL, NULL) == 0);
+		thread_join(tid[t]);
 		if (t < zopt_datasets)
 			ztest_dataset_close(zs, t);
 	}
@@ -5255,18 +5262,18 @@ ztest_run(ztest_shared_t *zs)
 	zs->zs_alloc = metaslab_class_get_alloc(spa_normal_class(spa));
 	zs->zs_space = metaslab_class_get_space(spa_normal_class(spa));
 
-	umem_free(tid, zopt_threads * sizeof (thread_t));
+	umem_free(tid, zopt_threads * sizeof (kt_did_t));
 
 	/* Kill the resume thread */
 	ztest_exiting = B_TRUE;
-	VERIFY(thr_join(resume_tid, NULL, NULL) == 0);
+	thread_join(resume_thread->t_tid);
 	ztest_resume(spa);
 
 	/*
 	 * Right before closing the pool, kick off a bunch of async I/O;
 	 * spa_close() should wait for it to complete.
 	 */
-	for (uint64_t object = 1; object < 50; object++)
+	for (object = 1; object < 50; object++)
 		dmu_prefetch(spa->spa_meta_objset, object, 0, 1ULL << 20);
 
 	/* Verify that at least one commit cb was called in a timely fashion */
@@ -5426,8 +5433,8 @@ ztest_init(ztest_shared_t *zs)
 	spa_t *spa;
 	nvlist_t *nvroot, *props;
 
-	VERIFY(_mutex_init(&zs->zs_vdev_lock, USYNC_THREAD, NULL) == 0);
-	VERIFY(rwlock_init(&zs->zs_name_lock, USYNC_THREAD, NULL) == 0);
+	mutex_init(&zs->zs_vdev_lock, NULL, MUTEX_DEFAULT, NULL);
+	rw_init(&zs->zs_name_lock, NULL, RW_DEFAULT, NULL);
 
 	kernel_init(FREAD | FWRITE);
 
@@ -5456,8 +5463,8 @@ ztest_init(ztest_shared_t *zs)
 
 	ztest_run_zdb(zs->zs_pool);
 
-	(void) rwlock_destroy(&zs->zs_name_lock);
-	(void) _mutex_destroy(&zs->zs_vdev_lock);
+	(void) rw_destroy(&zs->zs_name_lock);
+	(void) mutex_destroy(&zs->zs_vdev_lock);
 }
 
 int
diff --git a/lib/libuutil/uu_misc.c b/lib/libuutil/uu_misc.c
index 578bf3294052..1b843effe65d 100644
--- a/lib/libuutil/uu_misc.c
+++ b/lib/libuutil/uu_misc.c
@@ -34,7 +34,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/debug.h>
-#include <thread.h>
 #include <unistd.h>
 #include <ctype.h>
 
@@ -68,11 +67,12 @@ static va_list		uu_panic_args;
 static pthread_t	uu_panic_thread;
 
 static uint32_t		_uu_main_error;
+static __thread int	_uu_main_thread = 0;
 
 void
 uu_set_error(uint_t code)
 {
-	if (thr_main() != 0) {
+	if (_uu_main_thread) {
 		_uu_main_error = code;
 		return;
 	}
@@ -101,7 +101,7 @@ uu_set_error(uint_t code)
 uint32_t
 uu_error(void)
 {
-	if (thr_main() != 0)
+	if (_uu_main_thread)
 		return (_uu_main_error);
 
 	if (uu_error_key_setup < 0)	/* can't happen? */
@@ -259,6 +259,7 @@ uu_init(void) __attribute__((constructor));
 static void
 uu_init(void)
 {
+	_uu_main_thread = 1;
 	(void) pthread_atfork(uu_lockup, uu_release, uu_release_child);
 }
 
diff --git a/lib/libzpool/include/sys/zfs_context.h b/lib/libzpool/include/sys/zfs_context.h
index fc543559bd39..55b117c218a1 100644
--- a/lib/libzpool/include/sys/zfs_context.h
+++ b/lib/libzpool/include/sys/zfs_context.h
@@ -49,8 +49,7 @@ extern "C" {
 #include <errno.h>
 #include <string.h>
 #include <strings.h>
-#include <synch.h>
-#include <thread.h>
+#include <pthread.h>
 #include <assert.h>
 #include <alloca.h>
 #include <umem.h>
@@ -90,6 +89,8 @@ extern "C" {
 #define	CE_PANIC	3	/* panic		*/
 #define	CE_IGNORE	4	/* print nothing	*/
 
+extern int aok;
+
 /*
  * ZFS debugging
  */
@@ -195,27 +196,55 @@ _NOTE(CONSTCOND) } while (0)
 /*
  * Threads
  */
-#define	curthread	((void *)(uintptr_t)thr_self())
-
-typedef struct kthread kthread_t;
-
-#define	thread_create(stk, stksize, func, arg, len, pp, state, pri)	\
-	zk_thread_create(func, arg)
-#define	thread_exit() thr_exit(NULL)
-#define	thread_join(t)	panic("libzpool cannot join threads")
+#define	TS_MAGIC		0x72f158ab4261e538ull
+#define	TS_RUN			0x00000002
+#ifdef __linux__
+#define	STACK_SIZE		8192	/* Linux x86 and amd64 */
+#else
+#define	STACK_SIZE		24576	/* Solaris */
+#endif
 
-#define	newproc(f, a, cid, pri, ctp, pid)	(ENOSYS)
+#ifdef NPTL_GUARD_WITHIN_STACK
+#define	EXTRA_GUARD_BYTES	PAGESIZE
+#else
+#define	EXTRA_GUARD_BYTES	0
+#endif
 
 /* in libzpool, p0 exists only to have its address taken */
-struct proc {
+typedef struct proc {
 	uintptr_t	this_is_never_used_dont_dereference_it;
-};
+} proc_t;
 
 extern struct proc p0;
 
-#define	PS_NONE		-1
+typedef void (*thread_func_t)(void *);
+typedef void (*thread_func_arg_t)(void *);
+typedef pthread_t kt_did_t;
 
-extern kthread_t *zk_thread_create(void (*func)(), void *arg);
+typedef struct kthread {
+	kt_did_t	t_tid;
+	thread_func_t	t_func;
+	void *		t_arg;
+} kthread_t;
+
+#define	tsd_get(key)			pthread_getspecific(key)
+#define	tsd_set(key, val)		pthread_setspecific(key, val)
+#define	curthread			zk_thread_current()
+#define	thread_exit			zk_thread_exit
+#define	thread_create(stk, stksize, func, arg, len, pp, state, pri)	\
+	zk_thread_create(stk, stksize, (thread_func_t)func, arg,	\
+			 len, NULL, state, pri)
+#define	thread_join(t)			zk_thread_join(t)
+#define	newproc(f,a,cid,pri,ctp,pid)	(ENOSYS)
+
+extern kthread_t *zk_thread_current(void);
+extern void zk_thread_exit(void);
+extern kthread_t *zk_thread_create(caddr_t stk, size_t  stksize,
+	thread_func_t func, void *arg, size_t len,
+	proc_t *pp, int state, pri_t pri);
+extern void zk_thread_join(kt_did_t tid);
+
+#define	PS_NONE		-1
 
 #define	issig(why)	(FALSE)
 #define	ISSIG(thr, why)	(FALSE)
@@ -223,55 +252,52 @@ extern kthread_t *zk_thread_create(void (*func)(), void *arg);
 /*
  * Mutexes
  */
+#define	MTX_MAGIC	0x9522f51362a6e326ull
+#define	MTX_INIT	((void *)NULL)
+#define	MTX_DEST	((void *)-1UL)
+
 typedef struct kmutex {
 	void		*m_owner;
-	boolean_t	initialized;
-	mutex_t		m_lock;
+	uint64_t	m_magic;
+	pthread_mutex_t	m_lock;
 } kmutex_t;
 
-#define	MUTEX_DEFAULT	USYNC_THREAD
-#undef	MUTEX_HELD
-#undef	MUTEX_NOT_HELD
-#define	MUTEX_HELD(m) _mutex_held(&(m)->m_lock)
+#define	MUTEX_DEFAULT	0
+#define MUTEX_HELD(m)	((m)->m_owner == curthread)
 #define	MUTEX_NOT_HELD(m) (!MUTEX_HELD(m))
 
-/*
- * Argh -- we have to get cheesy here because the kernel and userland
- * have different signatures for the same routine.
- */
-extern int _mutex_init(mutex_t *mp, int type, void *arg);
-extern int _mutex_destroy(mutex_t *mp);
-
-#define	mutex_init(mp, b, c, d)		zmutex_init((kmutex_t *)(mp))
-#define	mutex_destroy(mp)		zmutex_destroy((kmutex_t *)(mp))
-
-extern void zmutex_init(kmutex_t *mp);
-extern void zmutex_destroy(kmutex_t *mp);
+extern void mutex_init(kmutex_t *mp, char *name, int type, void *cookie);
+extern void mutex_destroy(kmutex_t *mp);
 extern void mutex_enter(kmutex_t *mp);
 extern void mutex_exit(kmutex_t *mp);
 extern int mutex_tryenter(kmutex_t *mp);
 extern void *mutex_owner(kmutex_t *mp);
+extern int mutex_held(kmutex_t *mp);
 
 /*
  * RW locks
  */
+#define	RW_MAGIC	0x4d31fb123648e78aull
+#define	RW_INIT		((void *)NULL)
+#define	RW_DEST		((void *)-1UL)
+
 typedef struct krwlock {
-	void		*rw_owner;
-	boolean_t	initialized;
-	rwlock_t	rw_lock;
+	void			*rw_owner;
+	void			*rw_wr_owner;
+	uint64_t		rw_magic;
+	pthread_rwlock_t	rw_lock;
+	uint_t			rw_readers;
 } krwlock_t;
 
 typedef int krw_t;
 
 #define	RW_READER	0
 #define	RW_WRITER	1
-#define	RW_DEFAULT	USYNC_THREAD
+#define RW_DEFAULT	RW_READER
 
-#undef RW_READ_HELD
-#define	RW_READ_HELD(x)		_rw_read_held(&(x)->rw_lock)
-
-#undef RW_WRITE_HELD
-#define	RW_WRITE_HELD(x)	_rw_write_held(&(x)->rw_lock)
+#define	RW_READ_HELD(x)		((x)->rw_readers > 0)
+#define	RW_WRITE_HELD(x)	((x)->rw_wr_owner == curthread)
+#define	RW_LOCK_HELD(x)		(RW_READ_HELD(x) || RW_WRITE_HELD(x))
 
 extern void rw_init(krwlock_t *rwlp, char *name, int type, void *arg);
 extern void rw_destroy(krwlock_t *rwlp);
@@ -289,9 +315,14 @@ extern gid_t *crgetgroups(cred_t *cr);
 /*
  * Condition variables
  */
-typedef cond_t kcondvar_t;
+#define CV_MAGIC	0xd31ea9a83b1b30c4ull
+
+typedef struct kcondvar {
+	uint64_t		cv_magic;
+	pthread_cond_t		cv;
+} kcondvar_t;
 
-#define	CV_DEFAULT	USYNC_THREAD
+#define	CV_DEFAULT	0
 
 extern void cv_init(kcondvar_t *cv, char *name, int type, void *arg);
 extern void cv_destroy(kcondvar_t *cv);
@@ -367,7 +398,7 @@ extern taskq_t	*taskq_create(const char *, int, pri_t, int, int, uint_t);
 extern taskqid_t taskq_dispatch(taskq_t *, task_func_t, void *, uint_t);
 extern void	taskq_destroy(taskq_t *);
 extern void	taskq_wait(taskq_t *);
-extern int	taskq_member(taskq_t *, void *);
+extern int	taskq_member(taskq_t *, kthread_t *);
 extern void	system_taskq_init(void);
 extern void	system_taskq_fini(void);
 
@@ -496,7 +527,7 @@ extern void delay(clock_t ticks);
 #define	minclsyspri	60
 #define	maxclsyspri	99
 
-#define	CPU_SEQID	(thr_self() & (max_ncpus - 1))
+#define	CPU_SEQID	(pthread_self() & (max_ncpus - 1))
 
 #define	kcred		NULL
 #define	CRED()		NULL
diff --git a/lib/libzpool/kernel.c b/lib/libzpool/kernel.c
index b64f03da4fe7..4bd08cdd450e 100644
--- a/lib/libzpool/kernel.c
+++ b/lib/libzpool/kernel.c
@@ -29,6 +29,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <zlib.h>
+#include <sys/signal.h>
 #include <sys/spa.h>
 #include <sys/stat.h>
 #include <sys/processor.h>
@@ -57,16 +58,156 @@ struct proc p0;
  * threads
  * =========================================================================
  */
-/*ARGSUSED*/
+
+pthread_cond_t kthread_cond = PTHREAD_COND_INITIALIZER;
+pthread_mutex_t kthread_lock = PTHREAD_MUTEX_INITIALIZER;
+pthread_key_t kthread_key;
+int kthread_nr = 0;
+
+static void
+thread_init(void)
+{
+	kthread_t *kt;
+
+	VERIFY3S(pthread_key_create(&kthread_key, NULL), ==, 0);
+
+	/* Create entry for primary kthread */
+	kt = umem_zalloc(sizeof(kthread_t), UMEM_NOFAIL);
+	kt->t_tid = pthread_self();
+	kt->t_func = NULL;
+
+	VERIFY3S(pthread_setspecific(kthread_key, kt), ==, 0);
+
+	/* Only the main thread should be running at the moment */
+	ASSERT3S(kthread_nr, ==, 0);
+	kthread_nr = 1;
+}
+
+static void
+thread_fini(void)
+{
+	kthread_t *kt = curthread;
+
+	ASSERT(pthread_equal(kt->t_tid, pthread_self()));
+	ASSERT3P(kt->t_func, ==, NULL);
+
+	umem_free(kt, sizeof(kthread_t));
+
+	/* Wait for all threads to exit via thread_exit() */
+	VERIFY3S(pthread_mutex_lock(&kthread_lock), ==, 0);
+
+	kthread_nr--; /* Main thread is exiting */
+
+	while (kthread_nr > 0)
+		VERIFY3S(pthread_cond_wait(&kthread_cond, &kthread_lock), ==,
+		    0);
+
+	ASSERT3S(kthread_nr, ==, 0);
+	VERIFY3S(pthread_mutex_unlock(&kthread_lock), ==, 0);
+
+	VERIFY3S(pthread_key_delete(kthread_key), ==, 0);
+}
+
 kthread_t *
-zk_thread_create(void (*func)(), void *arg)
+zk_thread_current(void)
+{
+	kthread_t *kt = pthread_getspecific(kthread_key);
+
+	ASSERT3P(kt, !=, NULL);
+
+	return kt;
+}
+
+void *
+zk_thread_helper(void *arg)
 {
-	thread_t tid;
+	kthread_t *kt = (kthread_t *) arg;
+
+	VERIFY3S(pthread_setspecific(kthread_key, kt), ==, 0);
 
-	VERIFY(thr_create(0, 0, (void *(*)(void *))func, arg, THR_DETACHED,
-	    &tid) == 0);
+	VERIFY3S(pthread_mutex_lock(&kthread_lock), ==, 0);
+	kthread_nr++;
+	VERIFY3S(pthread_mutex_unlock(&kthread_lock), ==, 0);
 
-	return ((void *)(uintptr_t)tid);
+	kt->t_tid = pthread_self();
+	((thread_func_arg_t) kt->t_func)(kt->t_arg);
+
+	/* Unreachable, thread must exit with thread_exit() */
+	abort();
+
+	return NULL;
+}
+
+kthread_t *
+zk_thread_create(caddr_t stk, size_t stksize, thread_func_t func, void *arg,
+	      size_t len, proc_t *pp, int state, pri_t pri)
+{
+	kthread_t *kt;
+	pthread_attr_t attr;
+	size_t stack;
+
+	ASSERT3S(state & ~TS_RUN, ==, 0);
+
+	kt = umem_zalloc(sizeof(kthread_t), UMEM_NOFAIL);
+	kt->t_func = func;
+	kt->t_arg = arg;
+
+	/*
+	 * The Solaris kernel stack size is 24k for x86/x86_64.
+	 * The Linux kernel stack size is 8k for x86/x86_64.
+	 *
+	 * We reduce the default stack size in userspace, to ensure
+	 * we observe stack overruns in user space as well as in
+	 * kernel space.  PTHREAD_STACK_MIN is the minimum stack
+	 * required for a NULL procedure in user space and is added
+	 * in to the stack requirements.
+	 *
+	 * Some buggy NPTL threading implementations include the
+	 * guard area within the stack size allocations.  In
+	 * this case we allocate an extra page to account for the
+	 * guard area since we only have two pages of usable stack
+	 * on Linux.
+	 */
+
+	stack = PTHREAD_STACK_MIN + MAX(stksize, STACK_SIZE) +
+			EXTRA_GUARD_BYTES;
+
+	VERIFY3S(pthread_attr_init(&attr), ==, 0);
+	VERIFY3S(pthread_attr_setstacksize(&attr, stack), ==, 0);
+	VERIFY3S(pthread_attr_setguardsize(&attr, PAGESIZE), ==, 0);
+
+	VERIFY3S(pthread_create(&kt->t_tid, &attr, &zk_thread_helper, kt),
+	    ==, 0);
+
+	VERIFY3S(pthread_attr_destroy(&attr), ==, 0);
+
+	return kt;
+}
+
+void
+zk_thread_exit(void)
+{
+	kthread_t *kt = curthread;
+
+	ASSERT(pthread_equal(kt->t_tid, pthread_self()));
+
+	umem_free(kt, sizeof(kthread_t));
+
+	pthread_mutex_lock(&kthread_lock);
+	kthread_nr--;
+	pthread_mutex_unlock(&kthread_lock);
+
+	pthread_cond_broadcast(&kthread_cond);
+	pthread_exit((void *)TS_MAGIC);
+}
+
+void
+zk_thread_join(kt_did_t tid)
+{
+	void *ret;
+
+	pthread_join((pthread_t)tid, &ret);
+	VERIFY3P(ret, ==, (void *)TS_MAGIC);
 }
 
 /*
@@ -97,42 +238,45 @@ kstat_delete(kstat_t *ksp)
  * mutexes
  * =========================================================================
  */
+
 void
-zmutex_init(kmutex_t *mp)
+mutex_init(kmutex_t *mp, char *name, int type, void *cookie)
 {
-	mp->m_owner = NULL;
-	mp->initialized = B_TRUE;
-	(void) _mutex_init(&mp->m_lock, USYNC_THREAD, NULL);
+	ASSERT3S(type, ==, MUTEX_DEFAULT);
+	ASSERT3P(cookie, ==, NULL);
+	mp->m_owner = MTX_INIT;
+	mp->m_magic = MTX_MAGIC;
+	VERIFY3S(pthread_mutex_init(&mp->m_lock, NULL), ==, 0);
 }
 
 void
-zmutex_destroy(kmutex_t *mp)
+mutex_destroy(kmutex_t *mp)
 {
-	ASSERT(mp->initialized == B_TRUE);
-	ASSERT(mp->m_owner == NULL);
-	(void) _mutex_destroy(&(mp)->m_lock);
-	mp->m_owner = (void *)-1UL;
-	mp->initialized = B_FALSE;
+	ASSERT3U(mp->m_magic, ==, MTX_MAGIC);
+	ASSERT3P(mp->m_owner, ==, MTX_INIT);
+	VERIFY3S(pthread_mutex_destroy(&(mp)->m_lock), ==, 0);
+	mp->m_owner = MTX_DEST;
+	mp->m_magic = 0;
 }
 
 void
 mutex_enter(kmutex_t *mp)
 {
-	ASSERT(mp->initialized == B_TRUE);
-	ASSERT(mp->m_owner != (void *)-1UL);
-	ASSERT(mp->m_owner != curthread);
-	VERIFY(mutex_lock(&mp->m_lock) == 0);
-	ASSERT(mp->m_owner == NULL);
+	ASSERT3U(mp->m_magic, ==, MTX_MAGIC);
+	ASSERT3P(mp->m_owner, !=, MTX_DEST);
+	ASSERT3P(mp->m_owner, !=, curthread);
+	VERIFY3S(pthread_mutex_lock(&mp->m_lock), ==, 0);
+	ASSERT3P(mp->m_owner, ==, MTX_INIT);
 	mp->m_owner = curthread;
 }
 
 int
 mutex_tryenter(kmutex_t *mp)
 {
-	ASSERT(mp->initialized == B_TRUE);
-	ASSERT(mp->m_owner != (void *)-1UL);
-	if (0 == mutex_trylock(&mp->m_lock)) {
-		ASSERT(mp->m_owner == NULL);
+	ASSERT3U(mp->m_magic, ==, MTX_MAGIC);
+	ASSERT3P(mp->m_owner, !=, MTX_DEST);
+	if (0 == pthread_mutex_trylock(&mp->m_lock)) {
+		ASSERT3P(mp->m_owner, ==, MTX_INIT);
 		mp->m_owner = curthread;
 		return (1);
 	} else {
@@ -143,53 +287,71 @@ mutex_tryenter(kmutex_t *mp)
 void
 mutex_exit(kmutex_t *mp)
 {
-	ASSERT(mp->initialized == B_TRUE);
-	ASSERT(mutex_owner(mp) == curthread);
-	mp->m_owner = NULL;
-	VERIFY(mutex_unlock(&mp->m_lock) == 0);
+	ASSERT3U(mp->m_magic, ==, MTX_MAGIC);
+	ASSERT3P(mutex_owner(mp), ==, curthread);
+	mp->m_owner = MTX_INIT;
+	VERIFY3S(pthread_mutex_unlock(&mp->m_lock), ==, 0);
 }
 
 void *
 mutex_owner(kmutex_t *mp)
 {
-	ASSERT(mp->initialized == B_TRUE);
+	ASSERT3U(mp->m_magic, ==, MTX_MAGIC);
 	return (mp->m_owner);
 }
 
+int
+mutex_held(kmutex_t *mp)
+{
+	return (mp->m_owner == curthread);
+}
+
 /*
  * =========================================================================
  * rwlocks
  * =========================================================================
  */
-/*ARGSUSED*/
+
 void
 rw_init(krwlock_t *rwlp, char *name, int type, void *arg)
 {
-	rwlock_init(&rwlp->rw_lock, USYNC_THREAD, NULL);
-	rwlp->rw_owner = NULL;
-	rwlp->initialized = B_TRUE;
+	ASSERT3S(type, ==, RW_DEFAULT);
+	ASSERT3P(arg, ==, NULL);
+	VERIFY3S(pthread_rwlock_init(&rwlp->rw_lock, NULL), ==, 0);
+	rwlp->rw_owner = RW_INIT;
+	rwlp->rw_wr_owner = RW_INIT;
+	rwlp->rw_readers = 0;
+	rwlp->rw_magic = RW_MAGIC;
 }
 
 void
 rw_destroy(krwlock_t *rwlp)
 {
-	rwlock_destroy(&rwlp->rw_lock);
-	rwlp->rw_owner = (void *)-1UL;
-	rwlp->initialized = B_FALSE;
+	ASSERT3U(rwlp->rw_magic, ==, RW_MAGIC);
+
+	VERIFY3S(pthread_rwlock_destroy(&rwlp->rw_lock), ==, 0);
+	rwlp->rw_magic = 0;
 }
 
 void
 rw_enter(krwlock_t *rwlp, krw_t rw)
 {
-	ASSERT(!RW_LOCK_HELD(rwlp));
-	ASSERT(rwlp->initialized == B_TRUE);
-	ASSERT(rwlp->rw_owner != (void *)-1UL);
-	ASSERT(rwlp->rw_owner != curthread);
+	ASSERT3U(rwlp->rw_magic, ==, RW_MAGIC);
+	ASSERT3P(rwlp->rw_owner, !=, curthread);
+	ASSERT3P(rwlp->rw_wr_owner, !=, curthread);
 
-	if (rw == RW_READER)
-		VERIFY(rw_rdlock(&rwlp->rw_lock) == 0);
-	else
-		VERIFY(rw_wrlock(&rwlp->rw_lock) == 0);
+	if (rw == RW_READER) {
+		VERIFY3S(pthread_rwlock_rdlock(&rwlp->rw_lock), ==, 0);
+		ASSERT3P(rwlp->rw_wr_owner, ==, RW_INIT);
+
+		atomic_inc_uint(&rwlp->rw_readers);
+	} else {
+		VERIFY3S(pthread_rwlock_wrlock(&rwlp->rw_lock), ==, 0);
+		ASSERT3P(rwlp->rw_wr_owner, ==, RW_INIT);
+		ASSERT3U(rwlp->rw_readers, ==, 0);
+
+		rwlp->rw_wr_owner = curthread;
+	}
 
 	rwlp->rw_owner = curthread;
 }
@@ -197,11 +359,16 @@ rw_enter(krwlock_t *rwlp, krw_t rw)
 void
 rw_exit(krwlock_t *rwlp)
 {
-	ASSERT(rwlp->initialized == B_TRUE);
-	ASSERT(rwlp->rw_owner != (void *)-1UL);
+	ASSERT3U(rwlp->rw_magic, ==, RW_MAGIC);
+	ASSERT(RW_LOCK_HELD(rwlp));
+
+	if (RW_READ_HELD(rwlp))
+		atomic_dec_uint(&rwlp->rw_readers);
+	else
+		rwlp->rw_wr_owner = RW_INIT;
 
-	rwlp->rw_owner = NULL;
-	VERIFY(rw_unlock(&rwlp->rw_lock) == 0);
+	rwlp->rw_owner = RW_INIT;
+	VERIFY3S(pthread_rwlock_unlock(&rwlp->rw_lock), ==, 0);
 }
 
 int
@@ -209,28 +376,36 @@ rw_tryenter(krwlock_t *rwlp, krw_t rw)
 {
 	int rv;
 
-	ASSERT(rwlp->initialized == B_TRUE);
-	ASSERT(rwlp->rw_owner != (void *)-1UL);
+	ASSERT3U(rwlp->rw_magic, ==, RW_MAGIC);
 
 	if (rw == RW_READER)
-		rv = rw_tryrdlock(&rwlp->rw_lock);
+		rv = pthread_rwlock_tryrdlock(&rwlp->rw_lock);
 	else
-		rv = rw_trywrlock(&rwlp->rw_lock);
+		rv = pthread_rwlock_trywrlock(&rwlp->rw_lock);
 
 	if (rv == 0) {
+		ASSERT3P(rwlp->rw_wr_owner, ==, RW_INIT);
+
+		if (rw == RW_READER)
+			atomic_inc_uint(&rwlp->rw_readers);
+		else {
+			ASSERT3U(rwlp->rw_readers, ==, 0);
+			rwlp->rw_wr_owner = curthread;
+		}
+
 		rwlp->rw_owner = curthread;
 		return (1);
 	}
 
+	VERIFY3S(rv, ==, EBUSY);
+
 	return (0);
 }
 
-/*ARGSUSED*/
 int
 rw_tryupgrade(krwlock_t *rwlp)
 {
-	ASSERT(rwlp->initialized == B_TRUE);
-	ASSERT(rwlp->rw_owner != (void *)-1UL);
+	ASSERT3U(rwlp->rw_magic, ==, RW_MAGIC);
 
 	return (0);
 }
@@ -240,26 +415,32 @@ rw_tryupgrade(krwlock_t *rwlp)
  * condition variables
  * =========================================================================
  */
-/*ARGSUSED*/
+
 void
 cv_init(kcondvar_t *cv, char *name, int type, void *arg)
 {
-	VERIFY(cond_init(cv, type, NULL) == 0);
+	ASSERT3S(type, ==, CV_DEFAULT);
+	cv->cv_magic = CV_MAGIC;
+	VERIFY3S(pthread_cond_init(&cv->cv, NULL), ==, 0);
 }
 
 void
 cv_destroy(kcondvar_t *cv)
 {
-	VERIFY(cond_destroy(cv) == 0);
+	ASSERT3U(cv->cv_magic, ==, CV_MAGIC);
+	VERIFY3S(pthread_cond_destroy(&cv->cv), ==, 0);
+	cv->cv_magic = 0;
 }
 
 void
 cv_wait(kcondvar_t *cv, kmutex_t *mp)
 {
-	ASSERT(mutex_owner(mp) == curthread);
-	mp->m_owner = NULL;
-	int ret = cond_wait(cv, &mp->m_lock);
-	VERIFY(ret == 0 || ret == EINTR);
+	ASSERT3U(cv->cv_magic, ==, CV_MAGIC);
+	ASSERT3P(mutex_owner(mp), ==, curthread);
+	mp->m_owner = MTX_INIT;
+	int ret = pthread_cond_wait(&cv->cv, &mp->m_lock);
+	if (ret != 0)
+		VERIFY3S(ret, ==, EINTR);
 	mp->m_owner = curthread;
 }
 
@@ -267,29 +448,38 @@ clock_t
 cv_timedwait(kcondvar_t *cv, kmutex_t *mp, clock_t abstime)
 {
 	int error;
+	struct timeval tv;
 	timestruc_t ts;
 	clock_t delta;
 
+	ASSERT3U(cv->cv_magic, ==, CV_MAGIC);
+
 top:
 	delta = abstime - ddi_get_lbolt();
 	if (delta <= 0)
 		return (-1);
 
-	ts.tv_sec = delta / hz;
-	ts.tv_nsec = (delta % hz) * (NANOSEC / hz);
+	VERIFY(gettimeofday(&tv, NULL) == 0);
+
+	ts.tv_sec = tv.tv_sec + delta / hz;
+	ts.tv_nsec = tv.tv_usec * 1000 + (delta % hz) * (NANOSEC / hz);
+	if (ts.tv_nsec >= NANOSEC) {
+		ts.tv_sec++;
+		ts.tv_nsec -= NANOSEC;
+	}
 
-	ASSERT(mutex_owner(mp) == curthread);
-	mp->m_owner = NULL;
-	error = cond_reltimedwait(cv, &mp->m_lock, &ts);
+	ASSERT3P(mutex_owner(mp), ==, curthread);
+	mp->m_owner = MTX_INIT;
+	error = pthread_cond_timedwait(&cv->cv, &mp->m_lock, &ts);
 	mp->m_owner = curthread;
 
-	if (error == ETIME)
+	if (error == ETIMEDOUT)
 		return (-1);
 
 	if (error == EINTR)
 		goto top;
 
-	ASSERT(error == 0);
+	VERIFY3S(error, ==, 0);
 
 	return (1);
 }
@@ -297,13 +487,15 @@ cv_timedwait(kcondvar_t *cv, kmutex_t *mp, clock_t abstime)
 void
 cv_signal(kcondvar_t *cv)
 {
-	VERIFY(cond_signal(cv) == 0);
+	ASSERT3U(cv->cv_magic, ==, CV_MAGIC);
+	VERIFY3S(pthread_cond_signal(&cv->cv), ==, 0);
 }
 
 void
 cv_broadcast(kcondvar_t *cv)
 {
-	VERIFY(cond_broadcast(cv) == 0);
+	ASSERT3U(cv->cv_magic, ==, CV_MAGIC);
+	VERIFY3S(pthread_cond_broadcast(&cv->cv), ==, 0);
 }
 
 /*
@@ -571,7 +763,7 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
 		if (dprintf_find_string("pid"))
 			(void) printf("%d ", getpid());
 		if (dprintf_find_string("tid"))
-			(void) printf("%u ", thr_self());
+			(void) printf("%u ", (uint_t) pthread_self());
 		if (dprintf_find_string("cpu"))
 			(void) printf("%u ", getcpuid());
 		if (dprintf_find_string("time"))
@@ -824,6 +1016,7 @@ kernel_init(int mode)
 	VERIFY((random_fd = open("/dev/random", O_RDONLY)) != -1);
 	VERIFY((urandom_fd = open("/dev/urandom", O_RDONLY)) != -1);
 
+	thread_init();
 	system_taskq_init();
 
 	spa_init(mode);
@@ -835,6 +1028,7 @@ kernel_fini(void)
 	spa_fini();
 
 	system_taskq_fini();
+	thread_fini();
 
 	close(random_fd);
 	close(urandom_fd);
diff --git a/lib/libzpool/taskq.c b/lib/libzpool/taskq.c
index 8db5d11c1327..36c0ec7dfc78 100644
--- a/lib/libzpool/taskq.c
+++ b/lib/libzpool/taskq.c
@@ -42,7 +42,7 @@ struct taskq {
 	krwlock_t	tq_threadlock;
 	kcondvar_t	tq_dispatch_cv;
 	kcondvar_t	tq_wait_cv;
-	thread_t	*tq_threadlist;
+	kthread_t	**tq_threadlist;
 	int		tq_flags;
 	int		tq_active;
 	int		tq_nthreads;
@@ -154,7 +154,7 @@ taskq_wait(taskq_t *tq)
 	mutex_exit(&tq->tq_lock);
 }
 
-static void *
+static void
 taskq_thread(void *arg)
 {
 	taskq_t *tq = arg;
@@ -183,7 +183,7 @@ taskq_thread(void *arg)
 	tq->tq_nthreads--;
 	cv_broadcast(&tq->tq_wait_cv);
 	mutex_exit(&tq->tq_lock);
-	return (NULL);
+	thread_exit();
 }
 
 /*ARGSUSED*/
@@ -219,7 +219,7 @@ taskq_create(const char *name, int nthreads, pri_t pri,
 	tq->tq_maxalloc = maxalloc;
 	tq->tq_task.task_next = &tq->tq_task;
 	tq->tq_task.task_prev = &tq->tq_task;
-	tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP);
+	tq->tq_threadlist = kmem_alloc(nthreads*sizeof(kthread_t *), KM_SLEEP);
 
 	if (flags & TASKQ_PREPOPULATE) {
 		mutex_enter(&tq->tq_lock);
@@ -229,8 +229,8 @@ taskq_create(const char *name, int nthreads, pri_t pri,
 	}
 
 	for (t = 0; t < nthreads; t++)
-		(void) thr_create(0, 0, taskq_thread,
-		    tq, THR_BOUND, &tq->tq_threadlist[t]);
+		VERIFY((tq->tq_threadlist[t] = thread_create(NULL, 0,
+		    taskq_thread, tq, TS_RUN, NULL, 0, 0)) != NULL);
 
 	return (tq);
 }
@@ -238,7 +238,6 @@ taskq_create(const char *name, int nthreads, pri_t pri,
 void
 taskq_destroy(taskq_t *tq)
 {
-	int t;
 	int nthreads = tq->tq_nthreads;
 
 	taskq_wait(tq);
@@ -259,10 +258,7 @@ taskq_destroy(taskq_t *tq)
 
 	mutex_exit(&tq->tq_lock);
 
-	for (t = 0; t < nthreads; t++)
-		(void) thr_join(tq->tq_threadlist[t], NULL, NULL);
-
-	kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t));
+	kmem_free(tq->tq_threadlist, nthreads * sizeof (kthread_t *));
 
 	rw_destroy(&tq->tq_threadlock);
 	mutex_destroy(&tq->tq_lock);
@@ -274,7 +270,7 @@ taskq_destroy(taskq_t *tq)
 }
 
 int
-taskq_member(taskq_t *tq, void *t)
+taskq_member(taskq_t *tq, kthread_t *t)
 {
 	int i;
 
@@ -282,7 +278,7 @@ taskq_member(taskq_t *tq, void *t)
 		return (1);
 
 	for (i = 0; i < tq->tq_nthreads; i++)
-		if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t)
+		if (tq->tq_threadlist[i] == t)
 			return (1);
 
 	return (0);