task txg_sync:1328 blocked for more than 120 seconds.

[ioquatix]

Running on a system with 8GB of memory. The same system and similar problem as discussed in #2934

% pacman -Q | egrep "zfs|spl"
spl-git 0.6.5.3_r0_g7e85f6b_4.2.5_1-1
spl-utils-git 0.6.5.3_r0_g7e85f6b_4.2.5_1-1
zfs-git 0.6.5.3_r0_g9aaf60b_4.2.5_1-1
zfs-utils-git 0.6.5.3_r0_g9aaf60b_4.2.5_1-1

[293623.087748] INFO: task txg_sync:1328 blocked for more than 120 seconds.
[293623.087866]       Tainted: P           O    4.2.5-1-ARCH #1
[293623.087918] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[293623.087990] txg_sync        D 0000000000000000     0  1328      2 0x00000000
[293623.087997]  ffff8802200cba18 0000000000000046 ffff880090f18000 ffff8800cd793e80
[293623.088002]  ffff8802200cba48 ffff8802200cc000 ffff88022fc15200 7fffffffffffffff
[293623.088005]  ffff8800ccdfec50 0000000000000001 ffff8802200cba38 ffffffff8157283e
[293623.088009] Call Trace:
[293623.088021]  [<ffffffff8157283e>] schedule+0x3e/0x90
[293623.088026]  [<ffffffff81575205>] schedule_timeout+0x1b5/0x240
[293623.088033]  [<ffffffff810b4592>] ? __wake_up_common+0x52/0x90
[293623.088136]  [<ffffffff8101e769>] ? read_tsc+0x9/0x10
[293623.088140]  [<ffffffff81571d94>] io_schedule_timeout+0xa4/0x110
[293623.088174]  [<ffffffffa032fb60>] ? zio_taskq_member.isra.2+0x90/0x90 [zfs]
[293623.088182]  [<ffffffffa01ded28>] cv_wait_common+0xb8/0x140 [spl]
[293623.088186]  [<ffffffff810b4c80>] ? wake_atomic_t_function+0x60/0x60
[293623.088192]  [<ffffffffa01dee08>] __cv_wait_io+0x18/0x20 [spl]
[293623.088211]  [<ffffffffa0331d2e>] zio_wait+0x10e/0x1f0 [zfs]
[293623.088236]  [<ffffffffa02bb468>] dsl_pool_sync+0xb8/0x430 [zfs]
[293623.088262]  [<ffffffffa02d6fa9>] spa_sync+0x369/0xb30 [zfs]
[293623.088267]  [<ffffffff810b4c96>] ? autoremove_wake_function+0x16/0x40
[293623.088292]  [<ffffffffa02e85ae>] txg_sync_thread+0x3be/0x630 [zfs]
[293623.088374]  [<ffffffff810a9071>] ? put_prev_entity+0x31/0x420
[293623.088399]  [<ffffffffa02e81f0>] ? txg_delay+0x180/0x180 [zfs]
[293623.088405]  [<ffffffffa01d9ed1>] thread_generic_wrapper+0x71/0x80 [spl]
[293623.088411]  [<ffffffffa01d9e60>] ? __thread_exit+0x20/0x20 [spl]
[293623.088416]  [<ffffffff81092578>] kthread+0xd8/0xf0
[293623.088421]  [<ffffffff810924a0>] ? kthread_worker_fn+0x170/0x170
[293623.088424]  [<ffffffff8157665f>] ret_from_fork+0x3f/0x70
[293623.088428]  [<ffffffff810924a0>] ? kthread_worker_fn+0x170/0x170
[642705.138572] INFO: task txg_sync:1328 blocked for more than 120 seconds.
[642705.138684]       Tainted: P           O    4.2.5-1-ARCH #1
[642705.138736] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[642705.138808] txg_sync        D 0000000000000000     0  1328      2 0x00000000
[642705.138815]  ffff8802200cba18 0000000000000046 ffff880220894b00 ffff8800cd793e80
[642705.138820]  0000000000000000 ffff8802200cc000 ffff88022fc15200 7fffffffffffffff
[642705.138824]  ffff8800ccdfaf10 0000000000000001 ffff8802200cba38 ffffffff8157283e
[642705.138827] Call Trace:
[642705.138839]  [<ffffffff8157283e>] schedule+0x3e/0x90
[642705.138844]  [<ffffffff81575205>] schedule_timeout+0x1b5/0x240
[642705.138879]  [<ffffffffa032fb60>] ? zio_taskq_member.isra.2+0x90/0x90 [zfs]
[642705.138884]  [<ffffffff81572ae2>] ? preempt_schedule_common+0x22/0x40
[642705.138888]  [<ffffffff81572b24>] ? preempt_schedule+0x24/0x30
[642705.138893]  [<ffffffff81003012>] ? ___preempt_schedule+0x12/0x14
[642705.138898]  [<ffffffff8101e769>] ? read_tsc+0x9/0x10
[642705.138902]  [<ffffffff81571d94>] io_schedule_timeout+0xa4/0x110
[642705.138922]  [<ffffffffa032fb60>] ? zio_taskq_member.isra.2+0x90/0x90 [zfs]
[642705.138931]  [<ffffffffa01ded28>] cv_wait_common+0xb8/0x140 [spl]
[642705.138935]  [<ffffffff810b4c80>] ? wake_atomic_t_function+0x60/0x60
[642705.138941]  [<ffffffffa01dee08>] __cv_wait_io+0x18/0x20 [spl]
[642705.138960]  [<ffffffffa0331d2e>] zio_wait+0x10e/0x1f0 [zfs]
[642705.138985]  [<ffffffffa02bb676>] dsl_pool_sync+0x2c6/0x430 [zfs]
[642705.139011]  [<ffffffffa02d6fa9>] spa_sync+0x369/0xb30 [zfs]
[642705.139015]  [<ffffffff810b4c96>] ? autoremove_wake_function+0x16/0x40
[642705.139040]  [<ffffffffa02e85ae>] txg_sync_thread+0x3be/0x630 [zfs]
[642705.139046]  [<ffffffff810a9071>] ? put_prev_entity+0x31/0x420
[642705.139071]  [<ffffffffa02e81f0>] ? txg_delay+0x180/0x180 [zfs]
[642705.139077]  [<ffffffffa01d9ed1>] thread_generic_wrapper+0x71/0x80 [spl]
[642705.139083]  [<ffffffffa01d9e60>] ? __thread_exit+0x20/0x20 [spl]
[642705.139087]  [<ffffffff81092578>] kthread+0xd8/0xf0
[642705.139092]  [<ffffffff810924a0>] ? kthread_worker_fn+0x170/0x170
[642705.139096]  [<ffffffff8157665f>] ret_from_fork+0x3f/0x70
[642705.139100]  [<ffffffff810924a0>] ? kthread_worker_fn+0x170/0x170
[847977.118177] INFO: task jbd2/sde2-8:135 blocked for more than 120 seconds.
[847977.118290]       Tainted: P           O    4.2.5-1-ARCH #1
[847977.118342] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[847977.118414] jbd2/sde2-8     D 0000000000000001     0   135      2 0x00000000
[847977.118422]  ffff8800cfaafc78 0000000000000046 ffff8801ae14b200 ffff8802251fcb00
[847977.118426]  0000000000000001 ffff8800cfab0000 ffff8800cfaafd70 ffff8800cfaafd58
[847977.118430]  ffff8802251fcb00 ffff880104d69600 ffff8800cfaafc98 ffffffff8157283e
[847977.118434] Call Trace:
[847977.118446]  [<ffffffff8157283e>] schedule+0x3e/0x90
[847977.118456]  [<ffffffffa012d4e1>] jbd2_journal_commit_transaction+0x231/0x1890 [jbd2]
[847977.118463]  [<ffffffff810a8239>] ? dequeue_entity+0x149/0x690
[847977.118468]  [<ffffffff810a522b>] ? set_next_entity+0xab/0x440
[847977.118473]  [<ffffffff810b4c80>] ? wake_atomic_t_function+0x60/0x60
[847977.118478]  [<ffffffff810dca8e>] ? try_to_del_timer_sync+0x5e/0x90
[847977.118484]  [<ffffffffa0133b4a>] kjournald2+0xca/0x250 [jbd2]
[847977.118488]  [<ffffffff810b4c80>] ? wake_atomic_t_function+0x60/0x60
[847977.118493]  [<ffffffffa0133a80>] ? commit_timeout+0x10/0x10 [jbd2]
[847977.118498]  [<ffffffff81092578>] kthread+0xd8/0xf0
[847977.118503]  [<ffffffff810924a0>] ? kthread_worker_fn+0x170/0x170
[847977.118507]  [<ffffffff8157665f>] ret_from_fork+0x3f/0x70
[847977.118511]  [<ffffffff810924a0>] ? kthread_worker_fn+0x170/0x170
[847977.118515] INFO: task systemd-journal:161 blocked for more than 120 seconds.
[847977.118625]       Tainted: P           O    4.2.5-1-ARCH #1
[847977.118676] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[847977.118746] systemd-journal D ffff88022fc95200     0   161      1 0x00000000
[847977.118750]  ffff88022517b7c8 0000000000000086 ffff8802261f8c80 ffff8800cf85f080
[847977.118754]  ffff88022517b7c8 ffff88022517c000 ffff88022fc95200 7fffffffffffffff
[847977.118758]  0000000000000002 ffffffff81573110 ffff88022517b7e8 ffffffff8157283e
[847977.118761] Call Trace:
[847977.118765]  [<ffffffff81573110>] ? bit_wait+0x50/0x50
[847977.118769]  [<ffffffff8157283e>] schedule+0x3e/0x90
[847977.118772]  [<ffffffff81575205>] schedule_timeout+0x1b5/0x240
[847977.118778]  [<ffffffff81245808>] ? kernfs_path+0x48/0x60
[847977.118783]  [<ffffffff812aaebb>] ? cfq_del_cfqq_rr+0x10b/0x280
[847977.118787]  [<ffffffff8101e769>] ? read_tsc+0x9/0x10
[847977.118791]  [<ffffffff81573110>] ? bit_wait+0x50/0x50
[847977.118795]  [<ffffffff81571d94>] io_schedule_timeout+0xa4/0x110
[847977.118799]  [<ffffffff810b4744>] ? prepare_to_wait_exclusive+0x54/0x80
[847977.118802]  [<ffffffff81573145>] bit_wait_io+0x35/0x50
[847977.118806]  [<ffffffff81572f2b>] __wait_on_bit_lock+0x4b/0xa0
[847977.118810]  [<ffffffff812ba5b2>] ? radix_tree_lookup_slot+0x22/0x50
[847977.118814]  [<ffffffff81573110>] ? bit_wait+0x50/0x50
[847977.118818]  [<ffffffff81573002>] out_of_line_wait_on_bit_lock+0x82/0xb0
[847977.118822]  [<ffffffff810b4cc0>] ? autoremove_wake_function+0x40/0x40
[847977.118827]  [<ffffffff81203f67>] __lock_buffer+0x27/0x30
[847977.118833]  [<ffffffffa012bb6c>] do_get_write_access+0x1ec/0x510 [jbd2]
[847977.118836]  [<ffffffff81205929>] ? __find_get_block+0x109/0x110
[847977.118841]  [<ffffffffa012bec7>] jbd2_journal_get_write_access+0x37/0x70 [jbd2]
[847977.118857]  [<ffffffffa018c391>] __ext4_journal_get_write_access+0x31/0x70 [ext4]
[847977.118867]  [<ffffffffa015cde5>] ext4_reserve_inode_write+0x75/0xa0 [ext4]
[847977.118876]  [<ffffffffa0160388>] ? ext4_dirty_inode+0x48/0x70 [ext4]
[847977.118885]  [<ffffffffa015ce5e>] ext4_mark_inode_dirty+0x4e/0x220 [ext4]
[847977.118894]  [<ffffffffa0160388>] ext4_dirty_inode+0x48/0x70 [ext4]
[847977.118897]  [<ffffffff811fc648>] __mark_inode_dirty+0x48/0x380
[847977.118902]  [<ffffffff811ea579>] generic_update_time+0x79/0xc0
[847977.118906]  [<ffffffff811ea6e4>] file_update_time+0xb4/0x110
[847977.118915]  [<ffffffffa0160584>] ext4_page_mkwrite+0x64/0x450 [ext4]
[847977.118918]  [<ffffffff810b4592>] ? __wake_up_common+0x52/0x90
[847977.118922]  [<ffffffff810b4cc0>] ? autoremove_wake_function+0x40/0x40
[847977.118926]  [<ffffffff81185376>] do_page_mkwrite+0x56/0xb0
[847977.118930]  [<ffffffff811878a9>] do_wp_page+0x279/0x5e0
[847977.118934]  [<ffffffff8118a59c>] handle_mm_fault+0xc8c/0x18b0
[847977.118938]  [<ffffffff811d5ac1>] ? cp_new_stat+0x121/0x150
[847977.118942]  [<ffffffff81063439>] __do_page_fault+0x189/0x450
[847977.118945]  [<ffffffff81063722>] do_page_fault+0x22/0x30
[847977.118949]  [<ffffffff81578198>] page_fault+0x28/0x30
[847977.119077] INFO: task kworker/u8:2:11862 blocked for more than 120 seconds.
[847977.119180]       Tainted: P           O    4.2.5-1-ARCH #1
[847977.119231] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[847977.119301] kworker/u8:2    D ffff88022fc95200     0 11862      2 0x00000000
[847977.119308] Workqueue: writeback wb_workfn (flush-8:64)
[847977.119311]  ffff880204f937d8 0000000000000046 ffff8802261f8c80 ffff8801ae14b200
[847977.119315]  ffff8802251fcb00 ffff880204f94000 0000000000000000 ffff8800cf8be870
[847977.119318]  00000000003052ed ffff880104d69600 ffff880204f937f8 ffffffff8157283e
[847977.119321] Call Trace:
[847977.119326]  [<ffffffff8157283e>] schedule+0x3e/0x90
[847977.119331]  [<ffffffffa012a08d>] wait_transaction_locked+0x8d/0xd0 [jbd2]
[847977.119335]  [<ffffffff810b4c80>] ? wake_atomic_t_function+0x60/0x60
[847977.119340]  [<ffffffffa012a4a5>] start_this_handle+0x355/0x5c0 [jbd2]
[847977.119344]  [<ffffffff81575b7c>] ? _raw_write_unlock+0x1c/0x20
[847977.119348]  [<ffffffff811b3baa>] ? kmem_cache_alloc+0x1da/0x200
[847977.119353]  [<ffffffffa012aaac>] jbd2__journal_start+0xdc/0x1f0 [jbd2]
[847977.119364]  [<ffffffffa015d451>] ? ext4_writepages+0x421/0xcd0 [ext4]
[847977.119374]  [<ffffffffa018c0dd>] __ext4_journal_start_sb+0x6d/0x120 [ext4]
[847977.119383]  [<ffffffffa015d451>] ext4_writepages+0x421/0xcd0 [ext4]
[847977.119388]  [<ffffffff810146ec>] ? __switch_to+0x25c/0x4a0
[847977.119392]  [<ffffffff810146ec>] ? __switch_to+0x25c/0x4a0
[847977.119396]  [<ffffffff812c85b5>] ? find_next_bit+0x15/0x20
[847977.119401]  [<ffffffff8116592e>] do_writepages+0x1e/0x30
[847977.119404]  [<ffffffff811fc9c5>] __writeback_single_inode+0x45/0x320
[847977.119408]  [<ffffffff811fd20d>] writeback_sb_inodes+0x29d/0x4e0
[847977.119412]  [<ffffffff811fd4dc>] __writeback_inodes_wb+0x8c/0xc0
[847977.119415]  [<ffffffff811fd744>] wb_writeback+0x234/0x2e0
[847977.119419]  [<ffffffff811fde52>] wb_workfn+0x132/0x510
[847977.119424]  [<ffffffff81099d02>] ? finish_task_switch+0x62/0x1b0
[847977.119428]  [<ffffffff8108c5db>] process_one_work+0x14b/0x440
[847977.119431]  [<ffffffff8108c918>] worker_thread+0x48/0x4a0
[847977.119435]  [<ffffffff8108c8d0>] ? process_one_work+0x440/0x440
[847977.119439]  [<ffffffff81092578>] kthread+0xd8/0xf0
[847977.119443]  [<ffffffff810924a0>] ? kthread_worker_fn+0x170/0x170
[847977.119447]  [<ffffffff8157665f>] ret_from_fork+0x3f/0x70
[847977.119451]  [<ffffffff810924a0>] ? kthread_worker_fn+0x170/0x170

[ioquatix]

I'm not sure if this issue is still relevant or not so feel free to close it.