Note: NVME0 info included for completeness;  the hang happens
only on NVME1!

NVME0 - struct device

(gdb) print *(struct device *)0xffff8fa87879e900
$83 = {dv_handle = {impl = 0xffffffff808112b0 <acpi_devhandle_impl>, {
      pointer = 0xffff8fb7a3358188, const_pointer = 0xffff8fb7a3358188, 
      uintptr = 18446620617612820872, integer = -123456096730744}}, 
  dv_class = DV_DULL, dv_list = {tqe_next = 0xffff8fa878c05cc0, 
    tqe_prev = 0xffff8fa87879e5d8}, 
  dv_cfdata = 0xffffffff80c46800 <cfdata+768>, 
  dv_cfdriver = 0xffffffff80c47be0 <nvme_cd>, 
  dv_cfattach = 0xffffffff80c01600 <nvme_pci_ca>, dv_unit = 0, 
  dv_xname = "nvme0\000\000\000\000\000\000\000\000\000\000", 
  dv_parent = 0xffff8fa87879e5c0, dv_depth = 4, dv_flags = 135, 
  dv_private = 0xffff9080fc13c000, dv_locators = 0xffff8fa8786f48c4, 
  dv_properties = 0xffff8fa8787bddd0, dv_localcount = 0xffff8fa8786f4900, 
  dv_pending = 0, dv_pending_list = {tqe_next = 0x1, tqe_prev = 0x1}, 
  dv_attaching = 0x0, dv_detaching = 0x0, dv_detached = false, 
  dv_activity_count = 0, dv_activity_handlers = 0x0, 
  dv_driver_suspend = 0xffffffff802726b8 <nvme_pci_suspend>, 
  dv_driver_resume = 0xffffffff802726a0 <nvme_pci_resume>, 
  dv_driver_shutdown = 0x0, dv_driver_child_register = 0x0, 
  dv_bus_private = 0xffff8fa878b23508, 
  dv_bus_suspend = 0xffffffff80243e2e <pci_child_suspend>, 
  dv_bus_resume = 0xffffffff802441d5 <pci_child_resume>, 
  dv_bus_shutdown = 0xffffffff80242fae <pci_child_shutdown>, 
  dv_bus_deregister = 0xffffffff80242f9c <pci_child_deregister>, 
  dv_class_private = 0x0, dv_class_suspend = 0x0, dv_class_resume = 0x0, 
  dv_class_deregister = 0x0, dv_add_gen = 1, dv_del_gen = 0, dv_lock = {
    dvl_nwait = 0, dvl_nlock = 0, dvl_holder = 0x0, dvl_mtx = {u = {
        mtxa_owner = 0, s = {mtxs_dummy = 0 '\000', mtxs_ipl = {
            _ipl = 0 '\000'}, mtxs_lock = 0 '\000', mtxs_unused = 0 '\000'}}}, 
    dvl_cv = {cv_opaque = {0x0, 0xffffffff8093825c}}}, dv_bus_suspensors = {
    0x0 <repeats 16 times>}, dv_driver_suspensors = {0x0 <repeats 16 times>}, 
  dv_class_suspensors = {0x0 <repeats 16 times>}, dv_garbage = {dg_devs = 0x0, 
    dg_ndevs = 0}}
-------------------
NVME0 (struct nvme_softc)

$84 = {sc_dev = 0xffff8fa87879e900, sc_ops = 0xffffffff80814700 <nvme_ops>, 
  sc_iot = 0xffffffff80c06700 <x86_mem>, sc_ioh = 18446621620213239808, 
  sc_ios = 12288, sc_dmat = 0xffffffff80c072e0 <pci_bus_dma64_tag>, 
  sc_intr_establish = 0xffffffff802727a3 <nvme_pci_intr_establish>, 
  sc_intr_disestablish = 0xffffffff802726d0 <nvme_pci_intr_disestablish>, 
  sc_ih = 0xffff8fa8787af940, sc_softih = 0xffff8fa8787afa00, 
  sc_rdy_to = 30000, sc_mps = 4096, sc_mdts = 65536, sc_max_sgl = 16, 
  sc_dstrd = 4, sc_identify = {vid = 5197, ssvid = 5197, 
    sn = "S3EWNX0K108171P     ", 
    mn = "Samsung SSD 960 PRO 512GB", ' ' <repeats 15 times>, fr = "2B6QCXP7", 
    rab = 2 '\002', ieee = "8%", cmic = 0 '\000', mdts = 9 '\t', cntlid = 2, 
    ver = 66048, rtd3r = 100000, rtd3e = 5000000, oaes = 0, ctrattr = 0, 
    _reserved1 = '\000' <repeats 11 times>, fguid = '\000' <repeats 15 times>, 
    _reserved2 = '\000' <repeats 127 times>, oacs = 7, acl = 7 '\a', 
    aerl = 3 '\003', frmw = 22 '\026', lpa = 3 '\003', elpe = 63 '?', 
    npss = 4 '\004', avscc = 1 '\001', apsta = 1 '\001', wctemp = 346, 
    cctemp = 349, mtfa = 0, hmpre = 0, hmmin = 0, untncap = {tnvmcap = {
        512110190592, 0}, unvmcap = {0, 0}}, rpmbs = 0, edstt = 0, 
    dsto = 0 '\000', fwug = 0 '\000', kas = 0, hctma = 0, mntmt = 0, 
    mxtmt = 0, sanicap = 0, _reserved3 = '\000' <repeats 179 times>, 
    sqes = 102 'f', cqes = 68 'D', maxcmd = 0, nn = 1, oncs = 31, fuses = 0, 
    fna = 5 '\005', vwc = 1 '\001', awun = 255, awupf = 0, nvscc = 1 '\001', 
    _reserved4 = "", acwu = 0, _reserved5 = "\000", sgls = 0, 
    _reserved6 = '\000' <repeats 227 times>, 
    subnqn = '\000' <repeats 255 times>, 
    _reserved7 = '\000' <repeats 767 times>, 
    _reserved8 = '\000' <repeats 255 times>, psd = {{mp = 690, 
        _reserved1 = 0 '\000', flags = 0 '\000', enlat = 0, exlat = 0, 
        rrt = 0 '\000', rrl = 0 '\000', rwt = 0 '\000', rwl = 0 '\000', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 550, 
        _reserved1 = 0 '\000', flags = 0 '\000', enlat = 0, exlat = 0, 
        rrt = 1 '\001', rrl = 1 '\001', rwt = 1 '\001', rwl = 1 '\001', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 510, 
        _reserved1 = 0 '\000', flags = 0 '\000', enlat = 0, exlat = 0, 
        rrt = 2 '\002', rrl = 2 '\002', rwt = 2 '\002', rwl = 2 '\002', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 500, 
        _reserved1 = 0 '\000', flags = 3 '\003', enlat = 210, exlat = 1200, 
        rrt = 3 '\003', rrl = 3 '\003', rwt = 3 '\003', rwl = 3 '\003', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 80, 
        _reserved1 = 0 '\000', flags = 3 '\003', enlat = 2000, exlat = 6000, 
        rrt = 4 '\004', rrl = 4 '\004', rwt = 4 '\004', rwl = 4 '\004', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 0, 
        _reserved1 = 0 '\000', flags = 0 '\000', enlat = 0, exlat = 0, 
        rrt = 0 '\000', rrl = 0 '\000', rwt = 0 '\000', rwl = 0 '\000', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"} <repeats 27 times>}, 
    vs = '\000' <repeats 207 times>...}, sc_nn = 1, 
  sc_namespaces = 0xffff8fa8786f4920, sc_use_mq = true, sc_nq = 7, 
  sc_admin_q = 0xffff8fa8787e7600, sc_q = 0xffff8fa87876eec0, sc_flags = 1, 
  sc_quirks = 0, 
  sc_modelname = "Samsung SSD 960 PRO 512GB", '\000' <repeats 55 times>}
-----------------------
NVME0 has 7 queues
	...
	sc_nq = 7, 
	...
------------------
NVME0 queue 0 header

$106 = {q_sc = 0xffff9080fc13c000, q_sq_mtx = {u = {mtxa_owner = 1537, s = {
        mtxs_dummy = 1 '\001', mtxs_ipl = {_ipl = 6 '\006'}, 
        mtxs_lock = 0 '\000', mtxs_unused = 0 '\000'}}}, q_cq_mtx = {u = {
      mtxa_owner = 1537, s = {mtxs_dummy = 1 '\001', mtxs_ipl = {
          _ipl = 6 '\006'}, mtxs_lock = 0 '\000', mtxs_unused = 0 '\000'}}}, 
  q_sq_dmamem = 0xffff8fa87876ef40, q_cq_dmamem = 0xffff8fa8787d6080, 
  q_nvmmu_dmamem = 0x0, q_sqtdbl = 4104, q_cqhdbl = 4108, q_id = 1, 
  q_entries = 1024, q_sq_tail = 437, q_cq_head = 437, q_cq_phase = 1, 
  q_ccb_mtx = {u = {mtxa_owner = 1537, s = {mtxs_dummy = 1 '\001', mtxs_ipl = {
          _ipl = 6 '\006'}, mtxs_lock = 0 '\000', mtxs_unused = 0 '\000'}}}, 
  q_ccb_wait = {cv_opaque = {0x0, 0xffffffff808e70b1}}, q_ccb_waiting = false, 
  q_nccbs = 1023, q_ccbs = 0xffff9081042b9000, q_ccb_list = {
    sqh_first = 0xffff9081042baf68, sqh_last = 0xffff9081042d6f10}, 
  q_ccb_prpls = 0xffff8fa8787d6100}
-------------------
NVME0 queues 0 thru 7

$109 = {cdw0 = 0, _reserved = 0, sqhd = 438, sqid = 1, cid = 55, flags = 0}
$110 = {cdw0 = 0, _reserved = 0, sqhd = 402, sqid = 2, cid = 315, flags = 1}
$111 = {cdw0 = 0, _reserved = 0, sqhd = 158, sqid = 3, cid = 66, flags = 1}
$112 = {cdw0 = 0, _reserved = 0, sqhd = 825, sqid = 4, cid = 797, flags = 0}
$113 = {cdw0 = 0, _reserved = 0, sqhd = 955, sqid = 5, cid = 155, flags = 1}
$114 = {cdw0 = 0, _reserved = 0, sqhd = 675, sqid = 6, cid = 6, flags = 1}
$115 = {cdw0 = 0, _reserved = 0, sqhd = 8, sqid = 7, cid = 12, flags = 1}

-------------------
NVME1 (struct device)

(gdb) print *(struct device *)0xffff8fa878d8b740
$85 = {dv_handle = {impl = 0x0, {pointer = 0x0, const_pointer = 0x0, 
      uintptr = 0, integer = 0}}, dv_class = DV_DULL, dv_list = {
    tqe_next = 0xffff8fa8799ea200, tqe_prev = 0xffff8fa878d8b418}, 
  dv_cfdata = 0xffffffff80c46800 <cfdata+768>, 
  dv_cfdriver = 0xffffffff80c47be0 <nvme_cd>, 
  dv_cfattach = 0xffffffff80c01600 <nvme_pci_ca>, dv_unit = 1, 
  dv_xname = "nvme1\000\000\000\000\000\000\000\000\000\000", 
  dv_parent = 0xffff8fa878d8b400, dv_depth = 8, dv_flags = 135, 
  dv_private = 0xffff9080fc13e000, dv_locators = 0xffff8fa8786f4b84, 
  dv_properties = 0xffff8fa8787bd7e8, dv_localcount = 0xffff8fa8786f4bc0, 
  dv_pending = 0, dv_pending_list = {tqe_next = 0x1, tqe_prev = 0x1}, 
  dv_attaching = 0x0, dv_detaching = 0x0, dv_detached = false, 
  dv_activity_count = 0, dv_activity_handlers = 0x0, 
  dv_driver_suspend = 0xffffffff802726b8 <nvme_pci_suspend>, 
  dv_driver_resume = 0xffffffff802726a0 <nvme_pci_resume>, 
  dv_driver_shutdown = 0x0, dv_driver_child_register = 0x0, 
  dv_bus_private = 0xffff8fa8794a7d08, 
  dv_bus_suspend = 0xffffffff80243e2e <pci_child_suspend>, 
  dv_bus_resume = 0xffffffff802441d5 <pci_child_resume>, 
  dv_bus_shutdown = 0xffffffff80242fae <pci_child_shutdown>, 
  dv_bus_deregister = 0xffffffff80242f9c <pci_child_deregister>, 
  dv_class_private = 0x0, dv_class_suspend = 0x0, dv_class_resume = 0x0, 
  dv_class_deregister = 0x0, dv_add_gen = 1, dv_del_gen = 0, dv_lock = {
    dvl_nwait = 0, dvl_nlock = 0, dvl_holder = 0x0, dvl_mtx = {u = {
        mtxa_owner = 0, s = {mtxs_dummy = 0 '\000', mtxs_ipl = {
            _ipl = 0 '\000'}, mtxs_lock = 0 '\000', mtxs_unused = 0 '\000'}}}, 
    dvl_cv = {cv_opaque = {0x0, 0xffffffff8093825c}}}, dv_bus_suspensors = {
    0x0 <repeats 16 times>}, dv_driver_suspensors = {0x0 <repeats 16 times>}, 
  dv_class_suspensors = {0x0 <repeats 16 times>}, dv_garbage = {dg_devs = 0x0, 
    dg_ndevs = 0}}
--------------------
NVME1 (struct nvme_softc)

$86 = {sc_dev = 0xffff8fa878d8b740, sc_ops = 0xffffffff80814700 <nvme_ops>, 
  sc_iot = 0xffffffff80c06700 <x86_mem>, sc_ioh = 18446621620214775808, 
  sc_ios = 12288, sc_dmat = 0xffffffff80c072e0 <pci_bus_dma64_tag>, 
  sc_intr_establish = 0xffffffff802727a3 <nvme_pci_intr_establish>, 
  sc_intr_disestablish = 0xffffffff802726d0 <nvme_pci_intr_disestablish>, 
  sc_ih = 0xffff8fa878d8d900, sc_softih = 0xffff8fa878d8da00, 
  sc_rdy_to = 20000, sc_mps = 4096, sc_mdts = 65536, sc_max_sgl = 16, 
  sc_dstrd = 4, sc_identify = {vid = 5197, ssvid = 5197, 
    sn = "S6S2NS0T528809P     ", 
    mn = "Samsung SSD 970 EVO Plus 2TB", ' ' <repeats 12 times>, 
    fr = "4B2QEXM7", rab = 2 '\002', ieee = "8%", cmic = 0 '\000', 
    mdts = 7 '\a', cntlid = 6, ver = 66304, rtd3r = 200000, rtd3e = 10000000, 
    oaes = 512, ctrattr = 16, _reserved1 = '\000' <repeats 11 times>, 
    fguid = '\000' <repeats 15 times>, 
    _reserved2 = '\000' <repeats 127 times>, oacs = 23, acl = 7 '\a', 
    aerl = 3 '\003', frmw = 22 '\026', lpa = 15 '\017', elpe = 63 '?', 
    npss = 4 '\004', avscc = 1 '\001', apsta = 1 '\001', wctemp = 355, 
    cctemp = 358, mtfa = 0, hmpre = 0, hmmin = 0, untncap = {tnvmcap = {
        2000398934016, 0}, unvmcap = {0, 0}}, rpmbs = 0, edstt = 35, 
    dsto = 0 '\000', fwug = 0 '\000', kas = 0, hctma = 1, mntmt = 313, 
    mxtmt = 356, sanicap = 3, 
    _reserved3 = "\000\000\000\000\000\000\000\000\001", '\000' <repeats 170 times>, sqes = 102 'f', cqes = 68 'D', maxcmd = 256, nn = 1, oncs = 87, 
    fuses = 0, fna = 5 '\005', vwc = 7 '\a', awun = 1023, awupf = 0, 
    nvscc = 1 '\001', _reserved4 = "", acwu = 0, _reserved5 = "\000", 
    sgls = 0, _reserved6 = '\000' <repeats 227 times>, 
    subnqn = "nqn.1994-11.com.samsung:nvme:980PRO:M.2:S6S2NS0T528809P     ", '\000' <repeats 195 times>, _reserved7 = '\000' <repeats 767 times>, 
    _reserved8 = '\000' <repeats 255 times>, psd = {{mp = 759, 
        _reserved1 = 0 '\000', flags = 0 '\000', enlat = 0, exlat = 0, 
        rrt = 0 '\000', rrl = 0 '\000', rwt = 0 '\000', rwl = 0 '\000', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 759, 
        _reserved1 = 0 '\000', flags = 0 '\000', enlat = 0, exlat = 200, 
        rrt = 1 '\001', rrl = 1 '\001', rwt = 1 '\001', rwl = 1 '\001', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 759, 
        _reserved1 = 0 '\000', flags = 0 '\000', enlat = 0, exlat = 1000, 
        rrt = 2 '\002', rrl = 2 '\002', rwt = 2 '\002', rwl = 2 '\002', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 500, 
        _reserved1 = 0 '\000', flags = 3 '\003', enlat = 2000, exlat = 1200, 
        rrt = 3 '\003', rrl = 3 '\003', rwt = 3 '\003', rwl = 3 '\003', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 50, 
        _reserved1 = 0 '\000', flags = 3 '\003', enlat = 500, exlat = 9500, 
        rrt = 4 '\004', rrl = 4 '\004', rwt = 4 '\004', rwl = 4 '\004', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"}, {mp = 0, 
        _reserved1 = 0 '\000', flags = 0 '\000', enlat = 0, exlat = 0, 
        rrt = 0 '\000', rrl = 0 '\000', rwt = 0 '\000', rwl = 0 '\000', 
        idlp = 0, ips = 0 '\000', _reserved2 = 0 '\000', actp = 0, ap = 0, 
        _reserved = "\000\000\000\000\000\000\000"} <repeats 27 times>}, 
    vs = '\000' <repeats 20 times>, "\001", '\000' <repeats 186 times>...}, 
  sc_nn = 1, sc_namespaces = 0xffff8fa8786f4be0, sc_use_mq = true, sc_nq = 16, 
  sc_admin_q = 0xffff8fa878d8db00, sc_q = 0xffff8fa878d8dc00, sc_flags = 1, 
  sc_quirks = 0, 
  sc_modelname = "Samsung SSD 970 EVO Plus 2TB", '\000' <repeats 52 times>}
----------------
NVME1 has 16 queues:
	...
	sc_use_mq = true, sc_nq = 16,
	...
---------------
NVME1 queue 0 header

$87 = {q_sc = 0xffff9080fc13e000, q_sq_mtx = {u = {mtxa_owner = 1537, s = {
        mtxs_dummy = 1 '\001', mtxs_ipl = {_ipl = 6 '\006'}, 
        mtxs_lock = 0 '\000', mtxs_unused = 0 '\000'}}}, q_cq_mtx = {u = {
      mtxa_owner = 1537, s = {mtxs_dummy = 1 '\001', mtxs_ipl = {
          _ipl = 6 '\006'}, mtxs_lock = 0 '\000', mtxs_unused = 0 '\000'}}}, 
  q_sq_dmamem = 0xffff8fa878da4140, q_cq_dmamem = 0xffff8fa878da41c0, 
  q_nvmmu_dmamem = 0x0, q_sqtdbl = 4104, q_cqhdbl = 4108, q_id = 1, 
  q_entries = 1024, q_sq_tail = 636, q_cq_head = 635, q_cq_phase = 0, 
  q_ccb_mtx = {u = {mtxa_owner = 1537, s = {mtxs_dummy = 1 '\001', mtxs_ipl = {
          _ipl = 6 '\006'}, mtxs_lock = 0 '\000', mtxs_unused = 0 '\000'}}}, 
  q_ccb_wait = {cv_opaque = {0x0, 0xffffffff808e70b1}}, q_ccb_waiting = false, 
  q_nccbs = 1023, q_ccbs = 0xffff9081043c7000, q_ccb_list = {
    sqh_first = 0xffff9081043dc180, sqh_last = 0xffff9081043e0c80}, 
  q_ccb_prpls = 0xffff8fa878da4240}
----------------
NVME1 queues 0 thru 15

$90 = {cdw0 = 0, _reserved = 0, sqhd = 636, sqid = 1, cid = 570, flags = 1}
$91 = {cdw0 = 0, _reserved = 0, sqhd = 660, sqid = 2, cid = 96, flags = 1}
$92 = {cdw0 = 0, _reserved = 0, sqhd = 720, sqid = 3, cid = 502, flags = 0}
$93 = {cdw0 = 0, _reserved = 0, sqhd = 548, sqid = 4, cid = 991, flags = 1}
$94 = {cdw0 = 0, _reserved = 0, sqhd = 97, sqid = 5, cid = 571, flags = 1}
$95 = {cdw0 = 0, _reserved = 0, sqhd = 254, sqid = 6, cid = 946, flags = 0}
$96 = {cdw0 = 0, _reserved = 0, sqhd = 393, sqid = 7, cid = 987, flags = 0}
$97 = {cdw0 = 0, _reserved = 0, sqhd = 994, sqid = 8, cid = 993, flags = 0}
$98 = {cdw0 = 0, _reserved = 0, sqhd = 817, sqid = 9, cid = 158, flags = 1}
$99 = {cdw0 = 0, _reserved = 0, sqhd = 642, sqid = 10, cid = 289, flags = 1}
$100 = {cdw0 = 0, _reserved = 0, sqhd = 636, sqid = 11, cid = 995, flags = 1}
$101 = {cdw0 = 0, _reserved = 0, sqhd = 327, sqid = 12, cid = 4, flags = 1}
$102 = {cdw0 = 0, _reserved = 0, sqhd = 806, sqid = 13, cid = 605, flags = 0}
$103 = {cdw0 = 0, _reserved = 0, sqhd = 646, sqid = 14, cid = 1000, flags = 1}
$104 = {cdw0 = 0, _reserved = 0, sqhd = 552, sqid = 15, cid = 51, flags = 0}
$105 = {cdw0 = 0, _reserved = 0, sqhd = 363, sqid = 16, cid = 108, flags = 1}