kern/189355: zfs panic on 10-stable

[Radim Kolar]

> Ok so thats what I thought it was could you see what vq is?
(kgdb) up 11
#11 0xc0cb8187 in vdev_queue_io_to_issue (vq=0xc46ab300)
    at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_queue.c:489
489             if (avl_numnodes(&vq->vq_active_tree) >= zfs_vdev_max_active)
Current language:  auto; currently minimal
(kgdb) print vq
$1 = (vdev_queue_t *) 0xc46ab300
(kgdb) print *vq
$2 = {vq_vdev = 0xc46ab000, vq_class = {{vqc_active = 0, vqc_queued_tree = {
        avl_root = 0x0,
        avl_compar = 0xc0cb7de0 <vdev_queue_timestamp_compare>,
        avl_offset = 476, avl_numnodes = 0, avl_size = 732}}, {
      vqc_active = 0, vqc_queued_tree = {avl_root = 0x0,
        avl_compar = 0xc0cb7de0 <vdev_queue_timestamp_compare>,
        avl_offset = 476, avl_numnodes = 0, avl_size = 732}}, {
      vqc_active = 1, vqc_queued_tree = {avl_root = 0x0,
        avl_compar = 0xc0cb7d70 <vdev_queue_offset_compare>,
        avl_offset = 476, avl_numnodes = 0, avl_size = 732}}, {
      vqc_active = 0, vqc_queued_tree = {avl_root = 0x0,
        avl_compar = 0xc0cb7d70 <vdev_queue_offset_compare>,
        avl_offset = 476, avl_numnodes = 0, avl_size = 732}}, {
      vqc_active = 0, vqc_queued_tree = {avl_root = 0xc486c794,
        avl_compar = 0xc0cb7d70 <vdev_queue_offset_compare>,
        avl_offset = 476, avl_numnodes = 1, avl_size = 732}}, {
      vqc_active = 0, vqc_queued_tree = {avl_root = 0x0,
        avl_compar = 0xc0cb7d70 <vdev_queue_offset_compare>,
        avl_offset = 476, avl_numnodes = 0, avl_size = 732}}},
  vq_active_tree = {avl_root = 0xc476fa70,
    avl_compar = 0xc0cb7d70 <vdev_queue_offset_compare>, avl_offset = 476,
    avl_numnodes = 1, avl_size = 732}, vq_last_offset = 5941966336,
  vq_io_complete_ts = 7702783485, vq_lock = {lock_object = {
      lo_name = 0xc0d6b0ff "vq->vq_lock", lo_flags = 40960000, lo_data = 0,
      lo_witness = 0x0}, sx_lock = 3290710800}}
(kgdb)