task arc_adapt:1702 blocked for more than 120 seconds

[chrisrd]

openzfs/spl@8920c69, behlendorf/zfs@525c13f, linux-3.3.0

The only thing active was an iscsi-exported zvol.

The short version:

# grep blocked /var/log/kern.log
[108079.445271] INFO: task arc_adapt:1702 blocked for more than 120 seconds.
[111793.842781] INFO: task arc_adapt:1702 blocked for more than 120 seconds.
[111913.661711] INFO: task arc_adapt:1702 blocked for more than 120 seconds.
[111913.663385] INFO: task zvol/8:1712 blocked for more than 120 seconds.
[111913.664761] INFO: task zvol/20:1724 blocked for more than 120 seconds.
[111913.666070] INFO: task txg_sync:5605 blocked for more than 120 seconds.
[111913.668842] INFO: task LIO_iblock:8358 blocked for more than 120 seconds.
[111913.670388] INFO: task iscsi_trx:8378 blocked for more than 120 seconds.
[111913.672152] INFO: task iscsi_np:8382 blocked for more than 120 seconds.
[112033.490684] INFO: task arc_adapt:1702 blocked for more than 120 seconds.

The long version:

[108079.445271] INFO: task arc_adapt:1702 blocked for more than 120 seconds.
[108079.445330] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[108079.445415] arc_adapt       D 00000000ffffffff     0  1702      2 0x00000000
[108079.445474]  ffff881800d7bcf0 0000000000000046 ffff880c039e21e0 00000000001d38c0
[108079.445563]  ffff881800d7bfd8 ffff881800d7a010 00000000001d38c0 00000000001d38c0
[108079.445650]  ffff881800d7bfd8 00000000001d38c0 ffff880bebd643c0 ffff880c039e21e0
[108079.445738] Call Trace:
[108079.445782]  [<ffffffff813e813f>] schedule+0x3f/0x60
[108079.445828]  [<ffffffff813e618f>] mutex_lock_nested+0x14f/0x2e0
[108079.445887]  [<ffffffffa02d91ae>] ? __cv_timedwait_common+0xde/0x290 [spl]
[108079.445945]  [<ffffffffa02d91ae>] ? __cv_timedwait_common+0xde/0x290 [spl]
[108079.446003]  [<ffffffffa02d91ae>] __cv_timedwait_common+0xde/0x290 [spl]
[108079.446059]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[108079.446113]  [<ffffffff8106cef0>] ? wake_up_bit+0x40/0x40
[108079.446164]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[108079.446239]  [<ffffffffa036b590>] ? arc_adjust_meta+0x230/0x230 [zfs]
[108079.446294]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[108079.446349]  [<ffffffffa02d9373>] __cv_timedwait_interruptible+0x13/0x20 [spl]
[108079.446439]  [<ffffffffa036b644>] arc_adapt_thread+0xb4/0xf0 [zfs]
[108079.446493]  [<ffffffffa02d1508>] thread_generic_wrapper+0x78/0x90 [spl]
[108079.446548]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[108079.446599]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[108079.446649]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[108079.446698]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[108079.446748]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[108079.446793] 1 lock held by arc_adapt/1702:
[108079.446834]  #0:  (&arc_reclaim_thr_lock){......}, at: [<ffffffffa02d91ae>] __cv_timedwait_common+0xde/0x290 [spl]
[111793.842781] INFO: task arc_adapt:1702 blocked for more than 120 seconds.
[111793.842840] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[111793.842925] arc_adapt       D 00000000ffffffff     0  1702      2 0x00000000
[111793.842983]  ffff881800d7bcf0 0000000000000046 ffff880c039e21e0 00000000001d38c0
[111793.843072]  ffff881800d7bfd8 ffff881800d7a010 00000000001d38c0 00000000001d38c0
[111793.843160]  ffff881800d7bfd8 00000000001d38c0 ffff880c0863a1e0 ffff880c039e21e0
[111793.843248] Call Trace:
[111793.843293]  [<ffffffff813e813f>] schedule+0x3f/0x60
[111793.843339]  [<ffffffff813e618f>] mutex_lock_nested+0x14f/0x2e0
[111793.843398]  [<ffffffffa02d91ae>] ? __cv_timedwait_common+0xde/0x290 [spl]
[111793.843455]  [<ffffffffa02d91ae>] ? __cv_timedwait_common+0xde/0x290 [spl]
[111793.843513]  [<ffffffffa02d91ae>] __cv_timedwait_common+0xde/0x290 [spl]
[111793.843569]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111793.843622]  [<ffffffff8106cef0>] ? wake_up_bit+0x40/0x40
[111793.843673]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111793.843750]  [<ffffffffa036b590>] ? arc_adjust_meta+0x230/0x230 [zfs]
[111793.843805]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111793.843860]  [<ffffffffa02d9373>] __cv_timedwait_interruptible+0x13/0x20 [spl]
[111793.843950]  [<ffffffffa036b644>] arc_adapt_thread+0xb4/0xf0 [zfs]
[111793.844004]  [<ffffffffa02d1508>] thread_generic_wrapper+0x78/0x90 [spl]
[111793.844060]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111793.844111]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[111793.844161]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[111793.844210]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[111793.844260]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[111793.844305] 1 lock held by arc_adapt/1702:
[111793.844346]  #0:  (&arc_reclaim_thr_lock){......}, at: [<ffffffffa02d91ae>] __cv_timedwait_common+0xde/0x290 [spl]
[111913.661711] INFO: task arc_adapt:1702 blocked for more than 120 seconds.
[111913.661770] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[111913.661855] arc_adapt       D 00000000ffffffff     0  1702      2 0x00000000
[111913.661914]  ffff881800d7bcf0 0000000000000046 ffff880c039e21e0 00000000001d38c0
[111913.662003]  ffff881800d7bfd8 ffff881800d7a010 00000000001d38c0 00000000001d38c0
[111913.662090]  ffff881800d7bfd8 00000000001d38c0 ffff880c0863a1e0 ffff880c039e21e0
[111913.662178] Call Trace:
[111913.662222]  [<ffffffff813e813f>] schedule+0x3f/0x60
[111913.662268]  [<ffffffff813e618f>] mutex_lock_nested+0x14f/0x2e0
[111913.662328]  [<ffffffffa02d91ae>] ? __cv_timedwait_common+0xde/0x290 [spl]
[111913.662386]  [<ffffffffa02d91ae>] ? __cv_timedwait_common+0xde/0x290 [spl]
[111913.662443]  [<ffffffffa02d91ae>] __cv_timedwait_common+0xde/0x290 [spl]
[111913.662499]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111913.662552]  [<ffffffff8106cef0>] ? wake_up_bit+0x40/0x40
[111913.662603]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111913.662681]  [<ffffffffa036b590>] ? arc_adjust_meta+0x230/0x230 [zfs]
[111913.662736]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111913.662791]  [<ffffffffa02d9373>] __cv_timedwait_interruptible+0x13/0x20 [spl]
[111913.662881]  [<ffffffffa036b644>] arc_adapt_thread+0xb4/0xf0 [zfs]
[111913.662935]  [<ffffffffa02d1508>] thread_generic_wrapper+0x78/0x90 [spl]
[111913.662990]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111913.663041]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[111913.663091]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[111913.663140]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[111913.663191]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[111913.663236] 1 lock held by arc_adapt/1702:
[111913.663277]  #0:  (&arc_reclaim_thr_lock){......}, at: [<ffffffffa02d91ae>] __cv_timedwait_common+0xde/0x290 [spl]
[111913.663385] INFO: task zvol/8:1712 blocked for more than 120 seconds.
[111913.663434] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[111913.663511] zvol/8          D ffff880be3eac330     0  1712      2 0x00000000
[111913.663569]  ffff881800fd9c00 0000000000000046 ffff881800e38000 00000000001d38c0
[111913.663656]  ffff881800fd9fd8 ffff881800fd8010 00000000001d38c0 00000000001d38c0
[111913.663743]  ffff881800fd9fd8 00000000001d38c0 ffff880be260a1e0 ffff881800e38000
[111913.663831] Call Trace:
[111913.663867]  [<ffffffff813e813f>] schedule+0x3f/0x60
[111913.663918]  [<ffffffffa02d944d>] cv_wait_common+0xad/0x1d0 [spl]
[111913.663997]  [<ffffffffa04029ac>] ? zil_async_to_sync+0x1fc/0x240 [zfs]
[111913.664049]  [<ffffffff8106cef0>] ? wake_up_bit+0x40/0x40
[111913.664100]  [<ffffffffa02d95a3>] __cv_wait+0x13/0x20 [spl]
[111913.664172]  [<ffffffffa0403b74>] zil_commit+0x84/0x740 [zfs]
[111913.664245]  [<ffffffffa03ef906>] ? zfs_range_unlock+0x186/0x2d0 [zfs]
[111913.664320]  [<ffffffffa0411e61>] zvol_write+0x191/0x410 [zfs]
[111913.664373]  [<ffffffffa02d24c7>] taskq_thread+0x237/0x5e0 [spl]
[111913.664427]  [<ffffffff8107d140>] ? try_to_wake_up+0x300/0x300
[111913.664479]  [<ffffffffa02d2290>] ? task_alloc+0x360/0x360 [spl]
[111913.664528]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[111913.664574]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[111913.664624]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[111913.664674]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[111913.664719] no locks held by zvol/8/1712.
[111913.664761] INFO: task zvol/20:1724 blocked for more than 120 seconds.
[111913.664810] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[111913.664888] zvol/20         D ffff8814bd9f2e10     0  1724      2 0x00000000
[111913.664945]  ffff881801587bd0 0000000000000046 ffff881800e58000 00000000001d38c0
[111913.665033]  ffff881801587fd8 ffff881801586010 00000000001d38c0 00000000001d38c0
[111913.665120]  ffff881801587fd8 00000000001d38c0 ffff880be25f8000 ffff881800e58000
[111913.665207] Call Trace:
[111913.665244]  [<ffffffff813e813f>] schedule+0x3f/0x60
[111913.665294]  [<ffffffffa02d944d>] cv_wait_common+0xad/0x1d0 [spl]
[111913.665344]  [<ffffffff8106cef0>] ? wake_up_bit+0x40/0x40
[111913.665395]  [<ffffffffa02d95a3>] __cv_wait+0x13/0x20 [spl]
[111913.665466]  [<ffffffffa0409d3b>] zio_wait+0x10b/0x190 [zfs]
[111913.665538]  [<ffffffffa0403f1a>] zil_commit+0x42a/0x740 [zfs]
[111913.665610]  [<ffffffffa0411e61>] zvol_write+0x191/0x410 [zfs]
[111913.665663]  [<ffffffffa02d24c7>] taskq_thread+0x237/0x5e0 [spl]
[111913.665713]  [<ffffffff8107d140>] ? try_to_wake_up+0x300/0x300
[111913.665766]  [<ffffffffa02d2290>] ? task_alloc+0x360/0x360 [spl]
[111913.665815]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[111913.665861]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[111913.665910]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[111913.665960]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[111913.666005] no locks held by zvol/20/1724.
[111913.666070] INFO: task txg_sync:5605 blocked for more than 120 seconds.
[111913.666120] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[111913.666197] txg_sync        D ffff8800224167d0     0  5605      2 0x00000000
[111913.666255]  ffff880bdf429b60 0000000000000046 ffff881800afc3c0 00000000001d38c0
[111913.666342]  ffff880bdf429fd8 ffff880bdf428010 00000000001d38c0 00000000001d38c0
[111913.666430]  ffff880bdf429fd8 00000000001d38c0 ffff880be25a0000 ffff881800afc3c0
[111913.666517] Call Trace:
[111913.666554]  [<ffffffff813e813f>] schedule+0x3f/0x60
[111913.666604]  [<ffffffffa02d944d>] cv_wait_common+0xad/0x1d0 [spl]
[111913.666653]  [<ffffffff8106cef0>] ? wake_up_bit+0x40/0x40
[111913.667981]  [<ffffffffa02d95a3>] __cv_wait+0x13/0x20 [spl]
[111913.668052]  [<ffffffffa0409d3b>] zio_wait+0x10b/0x190 [zfs]
[111913.668121]  [<ffffffffa039d99a>] dsl_pool_sync+0xca/0x4a0 [zfs]
[111913.668193]  [<ffffffffa03b0e77>] spa_sync+0x397/0x9d0 [zfs]
[111913.668243]  [<ffffffff81097e65>] ? lock_release_holdtime+0x35/0x170
[111913.668318]  [<ffffffffa03c3371>] txg_sync_thread+0x2f1/0x4d0 [zfs]
[111913.668393]  [<ffffffffa03c3080>] ? txg_do_callbacks+0x60/0x60 [zfs]
[111913.668447]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111913.668502]  [<ffffffffa02d1508>] thread_generic_wrapper+0x78/0x90 [spl]
[111913.668557]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[111913.668608]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[111913.668654]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[111913.668703]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[111913.668753]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[111913.668798] no locks held by txg_sync/5605.
[111913.668842] INFO: task LIO_iblock:8358 blocked for more than 120 seconds.
[111913.668893] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[111913.668970] LIO_iblock      D ffff880be6638000     0  8358      2 0x00000000
[111913.669028]  ffff880c06885b90 0000000000000046 ffff880be6638000 00000000001d38c0
[111913.669115]  ffff880c06885fd8 ffff880c06884010 00000000001d38c0 00000000001d38c0
[111913.669203]  ffff880c06885fd8 00000000001d38c0 ffff880c08618000 ffff880be6638000
[111913.669290] Call Trace:
[111913.669327]  [<ffffffff813e813f>] schedule+0x3f/0x60
[111913.669372]  [<ffffffff813e59d5>] schedule_timeout+0x205/0x2e0
[111913.669421]  [<ffffffff8107eeed>] ? sched_clock_cpu+0xcd/0x110
[111913.669469]  [<ffffffff81097e65>] ? lock_release_holdtime+0x35/0x170
[111913.669519]  [<ffffffff813e76d2>] ? wait_for_common+0xc2/0x170
[111913.669570]  [<ffffffff8120ccde>] ? do_raw_spin_unlock+0x5e/0xb0
[111913.669619]  [<ffffffff813e76da>] wait_for_common+0xca/0x170
[111913.669668]  [<ffffffff8107d140>] ? try_to_wake_up+0x300/0x300
[111913.669716]  [<ffffffff813e785d>] wait_for_completion+0x1d/0x20
[111913.669775]  [<ffffffffa05d3d88>] target_stop_task+0x58/0x90 [target_core_mod]
[111913.669857]  [<ffffffffa05d166e>] core_tmr_lun_reset+0x46e/0x730 [target_core_mod]
[111913.669940]  [<ffffffffa05d803b>] transport_processing_thread+0x3ab/0x460 [target_core_mod]
[111913.670021]  [<ffffffff8106cef0>] ? wake_up_bit+0x40/0x40
[111913.670073]  [<ffffffffa05d7c90>] ? transport_handle_cdb_direct+0xb0/0xb0 [target_core_mod]
[111913.670154]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[111913.670200]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[111913.670248]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[111913.670298]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[111913.670345] no locks held by LIO_iblock/8358.
[111913.670388] INFO: task iscsi_trx:8378 blocked for more than 120 seconds.
[111913.670437] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[111913.670515] iscsi_trx       D ffff880c013ca1e0     0  8378      2 0x00000004
[111913.670572]  ffff880c03bd9b20 0000000000000046 ffff880c013ca1e0 00000000001d38c0
[111913.670660]  ffff880c03bd9fd8 ffff880c03bd8010 00000000001d38c0 00000000001d38c0
[111913.670747]  ffff880c03bd9fd8 00000000001d38c0 ffff8808dff10000 ffff880c013ca1e0
[111913.670834] Call Trace:
[111913.670871]  [<ffffffff813e813f>] schedule+0x3f/0x60
[111913.670916]  [<ffffffff813e59d5>] schedule_timeout+0x205/0x2e0
[111913.670964]  [<ffffffff8107eeed>] ? sched_clock_cpu+0xcd/0x110
[111913.671013]  [<ffffffff81097e65>] ? lock_release_holdtime+0x35/0x170
[111913.671063]  [<ffffffff813e76d2>] ? wait_for_common+0xc2/0x170
[111913.671112]  [<ffffffff8120ccde>] ? do_raw_spin_unlock+0x5e/0xb0
[111913.671161]  [<ffffffff813e76da>] wait_for_common+0xca/0x170
[111913.671209]  [<ffffffff8107d140>] ? try_to_wake_up+0x300/0x300
[111913.671258]  [<ffffffff813e785d>] wait_for_completion+0x1d/0x20
[111913.671311]  [<ffffffffa05d3f1d>] transport_wait_for_tasks+0x15d/0x1b0 [target_core_mod]
[111913.671396]  [<ffffffffa05d8b05>] transport_generic_free_cmd+0x85/0x90 [target_core_mod]
[111913.671482]  [<ffffffffa049b0c6>] iscsit_free_cmd+0x26/0x60 [iscsi_target_mod]
[111913.671562]  [<ffffffffa049c8db>] iscsit_close_connection+0x3eb/0x660 [iscsi_target_mod]
[111913.671657]  [<ffffffffa04904c3>] iscsit_take_action_for_connection_exit+0x73/0xd0 [iscsi_target_mod]
[111913.671747]  [<ffffffffa04a0f9f>] iscsi_target_rx_thread+0x20f/0x1760 [iscsi_target_mod]
[111913.671832]  [<ffffffffa04a0d90>] ? iscsit_handle_text_cmd+0x3d0/0x3d0 [iscsi_target_mod]
[111913.671914]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[111913.671961]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[111913.672012]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[111913.672063]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[111913.672109] no locks held by iscsi_trx/8378.
[111913.672152] INFO: task iscsi_np:8382 blocked for more than 120 seconds.
[111913.672202] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[111913.672281] iscsi_np        D ffff880bec6e21e0     0  8382      2 0x00000004
[111913.672341]  ffff880c02769a60 0000000000000046 ffff880bec6e21e0 00000000001d38c0
[111913.672433]  ffff880c02769fd8 ffff880c02768010 00000000001d38c0 00000000001d38c0
[111913.672526]  ffff880c02769fd8 00000000001d38c0 ffff880c085d43c0 ffff880bec6e21e0
[111913.672618] Call Trace:
[111913.672656]  [<ffffffff813e813f>] schedule+0x3f/0x60
[111913.672703]  [<ffffffff813e59d5>] schedule_timeout+0x205/0x2e0
[111913.672753]  [<ffffffff8107eeed>] ? sched_clock_cpu+0xcd/0x110
[111913.672802]  [<ffffffff81097e65>] ? lock_release_holdtime+0x35/0x170
[111913.672853]  [<ffffffff813e76d2>] ? wait_for_common+0xc2/0x170
[111913.672901]  [<ffffffff8120ccde>] ? do_raw_spin_unlock+0x5e/0xb0
[111913.672952]  [<ffffffff813e76da>] wait_for_common+0xca/0x170
[111913.673001]  [<ffffffff8107d140>] ? try_to_wake_up+0x300/0x300
[111913.673051]  [<ffffffff813e785d>] wait_for_completion+0x1d/0x20
[111913.673104]  [<ffffffffa04905a5>] iscsit_cause_connection_reinstatement+0x85/0xb0 [iscsi_target_mod]
[111913.673194]  [<ffffffffa049bed5>] iscsit_stop_session+0x115/0x1d0 [iscsi_target_mod]
[111913.673277]  [<ffffffffa0493fa4>] iscsi_check_for_session_reinstatement+0x1e4/0x220 [iscsi_target_mod]
[111913.673366]  [<ffffffffa0495d45>] iscsi_target_check_for_existing_instances+0x35/0x40 [iscsi_target_mod]
[111913.673457]  [<ffffffffa049663f>] iscsi_target_start_negotiation+0x53f/0x7e0 [iscsi_target_mod]
[111913.673546]  [<ffffffffa0494e6d>] __iscsi_target_login_thread+0x6ed/0x12e0 [iscsi_target_mod]
[111913.673633]  [<ffffffffa0495a60>] ? __iscsi_target_login_thread+0x12e0/0x12e0 [iscsi_target_mod]
[111913.673721]  [<ffffffffa0495a91>] iscsi_target_login_thread+0x31/0x40 [iscsi_target_mod]
[111913.673803]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[111913.673851]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[111913.673901]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[111913.673953]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[111913.673999] 1 lock held by iscsi_np/8382:
[111913.674040]  #0:  (&tpg->np_login_lock){......}, at: [<ffffffffa049dd2f>] iscsit_access_np+0x9f/0x110 [iscsi_target_mod]
[112033.490684] INFO: task arc_adapt:1702 blocked for more than 120 seconds.
[112033.490740] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[112033.490825] arc_adapt       D 00000000ffffffff     0  1702      2 0x00000000
[112033.490883]  ffff881800d7bcf0 0000000000000046 ffff880c039e21e0 00000000001d38c0
[112033.490972]  ffff881800d7bfd8 ffff881800d7a010 00000000001d38c0 00000000001d38c0
[112033.491059]  ffff881800d7bfd8 00000000001d38c0 ffff880c0863a1e0 ffff880c039e21e0
[112033.491146] Call Trace:
[112033.491186]  [<ffffffff813e813f>] schedule+0x3f/0x60
[112033.491232]  [<ffffffff813e618f>] mutex_lock_nested+0x14f/0x2e0
[112033.491287]  [<ffffffffa02d91ae>] ? __cv_timedwait_common+0xde/0x290 [spl]
[112033.491344]  [<ffffffffa02d91ae>] ? __cv_timedwait_common+0xde/0x290 [spl]
[112033.491401]  [<ffffffffa02d91ae>] __cv_timedwait_common+0xde/0x290 [spl]
[112033.491457]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[112033.491509]  [<ffffffff8106cef0>] ? wake_up_bit+0x40/0x40
[112033.491560]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[112033.491626]  [<ffffffffa036b590>] ? arc_adjust_meta+0x230/0x230 [zfs]
[112033.491681]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[112033.491736]  [<ffffffffa02d9373>] __cv_timedwait_interruptible+0x13/0x20 [spl]
[112033.491825]  [<ffffffffa036b644>] arc_adapt_thread+0xb4/0xf0 [zfs]
[112033.491879]  [<ffffffffa02d1508>] thread_generic_wrapper+0x78/0x90 [spl]
[112033.491935]  [<ffffffffa02d1490>] ? __thread_create+0x360/0x360 [spl]
[112033.491985]  [<ffffffff8106c9be>] kthread+0xae/0xc0
[112033.492032]  [<ffffffff813f2da4>] kernel_thread_helper+0x4/0x10
[112033.492080]  [<ffffffff8106c910>] ? __init_kthread_worker+0x70/0x70
[112033.492131]  [<ffffffff813f2da0>] ? gs_change+0x13/0x13
[112033.492176] 1 lock held by arc_adapt/1702:
[112033.492217]  #0:  (&arc_reclaim_thr_lock){......}, at: [<ffffffffa02d91ae>] __cv_timedwait_common+0xde/0x290 [spl]

[chrisrd]

Oops, sorry, this should probably have been reported in #618

[behlendorf]

Closing because I'm not sure we have enough to go on here to resolve this and because #618 has been merged. Please go ahead and report a new issue if you still see this.