Server's load become high with tasks in D state, no choice but to reboot the system.
Could be related to the following ? :

https://bugzilla.kernel.org/show_bug.cgi?id=119841
https://www.redhat.com/archives/dm-devel/2016-June/msg00399.html
https://patchwork.kernel.org/patch/9223697/
https://xen.crc.id.au/bugs/view.php?id=75


ii  xen-hypervisor-4.4-amd64             4.4.2-0ubuntu0.14.04.7            amd64        Xen Hypervisor on AMD64
ii  linux-image-extra-4.4.0-47-generic   4.4.0-47.68~14.04.1               amd64        Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii  linux-image-4.4.0-47-generic         4.4.0-47.68~14.04.1               amd64        Linux kernel image for version 4.4.0 on 64 bit x86 SMP


kernel messages:
----------------


Nov 28 07:03:31 server1 kernel: [890070.994700] INFO: task blkback.3.xvda2:5756 blocked for more than 120 seconds.
Nov 28 07:03:31 server1 kernel: [890070.994758]       Not tainted 4.4.0-47-generic #68~14.04.1-Ubuntu
Nov 28 07:03:31 server1 kernel: [890070.994806] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Nov 28 07:03:31 server1 kernel: [890070.994884] blkback.3.xvda2 D ffff8800b7ff3928     0  5756      2 0x00000000
Nov 28 07:03:31 server1 kernel: [890070.994890]  ffff8800b7ff3928 ffffffff81e13500 ffff8800b6a4be80 ffff8800b7ff4000
Nov 28 07:03:31 server1 kernel: [890070.994895]  ffff88013a83cc18 ffff88013a83cc00 ffffffff00000000 fffffffe00000001
Nov 28 07:03:31 server1 kernel: [890070.994898]  ffff8800b7ff3940 ffffffff817fafc5 ffff8800b6a4be80 ffff8800b7ff39c0
Nov 28 07:03:31 server1 kernel: [890070.994902] Call Trace:
Nov 28 07:03:31 server1 kernel: [890070.994912]  [<ffffffff817fafc5>] schedule+0x35/0x80
Nov 28 07:03:31 server1 kernel: [890070.994917]  [<ffffffff817fd46a>] rwsem_down_write_failed+0x1da/0x320
Nov 28 07:03:31 server1 kernel: [890070.994923]  [<ffffffff81689577>] ? push+0x47/0x50
Nov 28 07:03:31 server1 kernel: [890070.994927]  [<ffffffff81689f07>] ? dm_kcopyd_copy+0x147/0x1f0
Nov 28 07:03:31 server1 kernel: [890070.994931]  [<ffffffff813e6a53>] call_rwsem_down_write_failed+0x13/0x20
Nov 28 07:03:31 server1 kernel: [890070.994933]  [<ffffffff817fcd7d>] ? down_write+0x2d/0x40
Nov 28 07:03:31 server1 kernel: [890070.994939]  [<ffffffffc0314dae>] __origin_write+0x6e/0x210 [dm_snapshot]
Nov 28 07:03:31 server1 kernel: [890070.994944]  [<ffffffff81185625>] ? mempool_alloc_slab+0x15/0x20
Nov 28 07:03:31 server1 kernel: [890070.994946]  [<ffffffff8118574f>] ? mempool_alloc+0x5f/0x150
Nov 28 07:03:31 server1 kernel: [890070.994949]  [<ffffffffc0314fb7>] do_origin.isra.14+0x67/0x90 [dm_snapshot]
Nov 28 07:03:31 server1 kernel: [890070.994952]  [<ffffffffc0315042>] origin_map+0x62/0x80 [dm_snapshot]
Nov 28 07:03:31 server1 kernel: [890070.994955]  [<ffffffff8167f2da>] __map_bio+0x3a/0x110
Nov 28 07:03:31 server1 kernel: [890070.994957]  [<ffffffff816809c0>] __split_and_process_bio+0x240/0x3c0
Nov 28 07:03:31 server1 kernel: [890070.994960]  [<ffffffff81680baa>] dm_make_request+0x6a/0xd0
Nov 28 07:03:31 server1 kernel: [890070.994964]  [<ffffffff813aa221>] generic_make_request+0xe1/0x1a0
Nov 28 07:03:31 server1 kernel: [890070.994968]  [<ffffffff813aa357>] submit_bio+0x77/0x150
Nov 28 07:03:31 server1 kernel: [890070.994971]  [<ffffffff813a1c71>] ? bio_alloc_bioset+0x181/0x2a0
Nov 28 07:03:31 server1 kernel: [890070.994977]  [<ffffffffc02c6a1d>] dispatch_rw_block_io+0x4fd/0x9b0 [xen_blkback]
Nov 28 07:03:31 server1 kernel: [890070.994981]  [<ffffffff8101c244>] ? xen_load_sp0+0x84/0x180
Nov 28 07:03:31 server1 kernel: [890070.994985]  [<ffffffffc02c70c5>] __do_block_io_op+0x1f5/0x650 [xen_blkback]
Nov 28 07:03:31 server1 kernel: [890070.994990]  [<ffffffff810e5e18>] ? del_timer_sync+0x48/0x50
Nov 28 07:03:31 server1 kernel: [890070.994993]  [<ffffffff817fd8ab>] ? schedule_timeout+0x16b/0x2d0
Nov 28 07:03:31 server1 kernel: [890070.994997]  [<ffffffffc02c7880>] xen_blkif_schedule+0xd0/0x820 [xen_blkback]
Nov 28 07:03:31 server1 kernel: [890070.995002]  [<ffffffff810a4e1a>] ? finish_task_switch+0x7a/0x290
Nov 28 07:03:31 server1 kernel: [890070.995004]  [<ffffffff817fa969>] ? __schedule+0x359/0x980
Nov 28 07:03:31 server1 kernel: [890070.995010]  [<ffffffff810bde70>] ? prepare_to_wait_event+0xf0/0xf0
Nov 28 07:03:31 server1 kernel: [890070.995014]  [<ffffffffc02c77b0>] ? xen_blkif_be_int+0x30/0x30 [xen_blkback]
Nov 28 07:03:31 server1 kernel: [890070.995018]  [<ffffffff8109ba29>] kthread+0xc9/0xe0
Nov 28 07:03:31 server1 kernel: [890070.995021]  [<ffffffff8109b960>] ? kthread_park+0x60/0x60
Nov 28 07:03:31 server1 kernel: [890070.995025]  [<ffffffff817febcf>] ret_from_fork+0x3f/0x70
Nov 28 07:03:31 server1 kernel: [890070.995027]  [<ffffffff8109b960>] ? kthread_park+0x60/0x60
Nov 28 07:03:31 server1 kernel: [890070.995033] INFO: task kworker/u4:1:8922 blocked for more than 120 seconds.
Nov 28 07:03:31 server1 kernel: [890070.995106]       Not tainted 4.4.0-47-generic #68~14.04.1-Ubuntu
Nov 28 07:03:31 server1 kernel: [890070.995148] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Nov 28 07:03:31 server1 kernel: [890070.995200] kworker/u4:1    D ffff8800a7fbb628     0  8922      2 0x00000000
Nov 28 07:03:31 server1 kernel: [890070.995208] Workqueue: writeback wb_workfn (flush-252:12)
Nov 28 07:03:31 server1 kernel: [890070.995210]  ffff8800a7fbb628 ffff880139ad3200 ffff8800b7dfcb00 ffff8800a7fbc000
Nov 28 07:03:31 server1 kernel: [890070.995212]  ffff88013a83cc18 ffff88013a83cc00 ffffffff00000000 fffffffe00000001
Nov 28 07:03:31 server1 kernel: [890070.995215]  ffff8800a7fbb640 ffffffff817fafc5 ffff8800b7dfcb00 ffff8800a7fbb6c0
Nov 28 07:03:31 server1 kernel: [890070.995217] Call Trace:
Nov 28 07:03:31 server1 kernel: [890070.995220]  [<ffffffff817fafc5>] schedule+0x35/0x80
Nov 28 07:03:31 server1 kernel: [890070.995223]  [<ffffffff817fd46a>] rwsem_down_write_failed+0x1da/0x320
Nov 28 07:03:31 server1 kernel: [890070.995229]  [<ffffffff811fad2a>] ? __slab_alloc+0x4d/0x5c
Nov 28 07:03:31 server1 kernel: [890070.995232]  [<ffffffff811dc3eb>] ? kmem_cache_alloc+0x1bb/0x200
Nov 28 07:03:31 server1 kernel: [890070.995236]  [<ffffffff813e6a53>] call_rwsem_down_write_failed+0x13/0x20
Nov 28 07:03:31 server1 kernel: [890070.995239]  [<ffffffff817fcd7d>] ? down_write+0x2d/0x40
Nov 28 07:03:31 server1 kernel: [890070.995244]  [<ffffffffc0315d12>] snapshot_map+0x62/0x390 [dm_snapshot]
Nov 28 07:03:31 server1 kernel: [890070.995272]  [<ffffffff8167f2da>] __map_bio+0x3a/0x110
Nov 28 07:03:31 server1 kernel: [890070.995275]  [<ffffffff816809c0>] __split_and_process_bio+0x240/0x3c0
Nov 28 07:03:31 server1 kernel: [890070.995278]  [<ffffffff81680baa>] dm_make_request+0x6a/0xd0
Nov 28 07:03:31 server1 kernel: [890070.995282]  [<ffffffff813aa221>] generic_make_request+0xe1/0x1a0
Nov 28 07:03:31 server1 kernel: [890070.995284]  [<ffffffff813aa357>] submit_bio+0x77/0x150
Nov 28 07:03:31 server1 kernel: [890070.995286]  [<ffffffff813a1c71>] ? bio_alloc_bioset+0x181/0x2a0
Nov 28 07:03:31 server1 kernel: [890070.995289]  [<ffffffff812347ef>] submit_bh_wbc+0x12f/0x160
Nov 28 07:03:31 server1 kernel: [890070.995292]  [<ffffffff81236615>] __block_write_full_page.constprop.39+0x125/0x360
Nov 28 07:03:31 server1 kernel: [890070.995293]  [<ffffffff81236af0>] ? I_BDEV+0x20/0x20
Nov 28 07:03:31 server1 kernel: [890070.995295]  [<ffffffff8123692e>] block_write_full_page+0xde/0x100
Nov 28 07:03:31 server1 kernel: [890070.995298]  [<ffffffff81237378>] blkdev_writepage+0x18/0x20
Nov 28 07:03:31 server1 kernel: [890070.995300]  [<ffffffff8118d253>] __writepage+0x13/0x40
Nov 28 07:03:31 server1 kernel: [890070.995302]  [<ffffffff8118e5c1>] write_cache_pages+0x241/0x4c0
Nov 28 07:03:31 server1 kernel: [890070.995304]  [<ffffffff8118d240>] ? wb_update_dirty_ratelimit+0x1c0/0x1c0
Nov 28 07:03:31 server1 kernel: [890070.995307]  [<ffffffff8118e883>] generic_writepages+0x43/0x60
Nov 28 07:03:31 server1 kernel: [890070.995310]  [<ffffffff8118d3ff>] ? __wb_calc_thresh+0x2f/0x120
Nov 28 07:03:31 server1 kernel: [890070.995313]  [<ffffffff8118f46e>] do_writepages+0x1e/0x30
Nov 28 07:03:31 server1 kernel: [890070.995316]  [<ffffffff8122b215>] __writeback_single_inode+0x45/0x340
Nov 28 07:03:31 server1 kernel: [890070.995319]  [<ffffffff8122ba4b>] writeback_sb_inodes+0x26b/0x5c0
Nov 28 07:03:31 server1 kernel: [890070.995322]  [<ffffffff8122be26>] __writeback_inodes_wb+0x86/0xc0
Nov 28 07:03:31 server1 kernel: [890070.995325]  [<ffffffff8122c0b2>] wb_writeback+0x252/0x2e0
Nov 28 07:03:31 server1 kernel: [890070.995328]  [<ffffffff8122c818>] wb_workfn+0x238/0x3d0
Nov 28 07:03:31 server1 kernel: [890070.995332]  [<ffffffff810c4e11>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
Nov 28 07:03:31 server1 kernel: [890070.995337]  [<ffffffff81095b40>] process_one_work+0x150/0x3f0
Nov 28 07:03:31 server1 kernel: [890070.995341]  [<ffffffff810962ba>] worker_thread+0x11a/0x470
Nov 28 07:03:31 server1 kernel: [890070.995345]  [<ffffffff817fa969>] ? __schedule+0x359/0x980
Nov 28 07:03:31 server1 kernel: [890070.995347]  [<ffffffff810961a0>] ? rescuer_thread+0x310/0x310
Nov 28 07:03:31 server1 kernel: [890070.995349]  [<ffffffff8109ba29>] kthread+0xc9/0xe0
Nov 28 07:03:31 server1 kernel: [890070.995351]  [<ffffffff8109b960>] ? kthread_park+0x60/0x60
Nov 28 07:03:31 server1 kernel: [890070.995354]  [<ffffffff817febcf>] ret_from_fork+0x3f/0x70
Nov 28 07:03:31 server1 kernel: [890070.995356]  [<ffffffff8109b960>] ? kthread_park+0x60/0x60
Nov 28 07:03:31 server1 kernel: [890070.995361] INFO: task fsck.ext4:11082 blocked for more than 120 seconds.
Nov 28 07:03:31 server1 kernel: [890070.995433]       Not tainted 4.4.0-47-generic #68~14.04.1-Ubuntu
Nov 28 07:03:31 server1 kernel: [890070.995475] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Nov 28 07:03:31 server1 kernel: [890070.995519] fsck.ext4       D ffff8800a7caf7d8     0 11082  11081 0x00000000
Nov 28 07:03:31 server1 kernel: [890070.995522]  ffff8800a7caf7d8 ffff88013b000000 ffff8800b8463200 ffff8800a7cb0000
Nov 28 07:03:31 server1 kernel: [890070.995525]  ffff88013a83cc18 ffff88013a83cc00 ffffffff00000000 fffffffe00000001
Nov 28 07:03:31 server1 kernel: [890070.995527]  ffff8800a7caf7f0 ffffffff817fafc5 ffff8800b8463200 ffff8800a7caf870
Nov 28 07:03:31 server1 kernel: [890070.995529] Call Trace:
Nov 28 07:03:31 server1 kernel: [890070.995532]  [<ffffffff817fafc5>] schedule+0x35/0x80
Nov 28 07:03:31 server1 kernel: [890070.995535]  [<ffffffff817fd46a>] rwsem_down_write_failed+0x1da/0x320
Nov 28 07:03:31 server1 kernel: [890070.995537]  [<ffffffff813e6a53>] call_rwsem_down_write_failed+0x13/0x20
Nov 28 07:03:31 server1 kernel: [890070.995539]  [<ffffffff817fcd7d>] ? down_write+0x2d/0x40
Nov 28 07:03:31 server1 kernel: [890070.995543]  [<ffffffffc0315d12>] snapshot_map+0x62/0x390 [dm_snapshot]
Nov 28 07:03:31 server1 kernel: [890070.995545]  [<ffffffff8167f2da>] __map_bio+0x3a/0x110
Nov 28 07:03:31 server1 kernel: [890070.995547]  [<ffffffff816809c0>] __split_and_process_bio+0x240/0x3c0
Nov 28 07:03:31 server1 kernel: [890070.995550]  [<ffffffff81680baa>] dm_make_request+0x6a/0xd0
Nov 28 07:03:31 server1 kernel: [890070.995553]  [<ffffffff813aa221>] generic_make_request+0xe1/0x1a0
Nov 28 07:03:31 server1 kernel: [890070.995555]  [<ffffffff813aa357>] submit_bio+0x77/0x150
Nov 28 07:03:31 server1 kernel: [890070.995558]  [<ffffffff81191245>] ? release_pages+0xc5/0x260
Nov 28 07:03:31 server1 kernel: [890070.995560]  [<ffffffff810c4e11>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
Nov 28 07:03:31 server1 kernel: [890070.995563]  [<ffffffff8123d3c9>] do_mpage_readpage+0x2d9/0x6d0
Nov 28 07:03:31 server1 kernel: [890070.995565]  [<ffffffff81191ade>] ? lru_cache_add+0xe/0x10
Nov 28 07:03:31 server1 kernel: [890070.995567]  [<ffffffff8123d8c3>] mpage_readpages+0x103/0x150
Nov 28 07:03:31 server1 kernel: [890070.995569]  [<ffffffff81236af0>] ? I_BDEV+0x20/0x20
Nov 28 07:03:31 server1 kernel: [890070.995571]  [<ffffffff81236af0>] ? I_BDEV+0x20/0x20
Nov 28 07:03:31 server1 kernel: [890070.995573]  [<ffffffff8123733d>] blkdev_readpages+0x1d/0x20
Nov 28 07:03:31 server1 kernel: [890070.995575]  [<ffffffff8118fb94>] __do_page_cache_readahead+0x174/0x200
Nov 28 07:03:31 server1 kernel: [890070.995577]  [<ffffffff8118fd55>] ondemand_readahead+0x135/0x260
Nov 28 07:03:31 server1 kernel: [890070.995579]  [<ffffffff8168033a>] ? dm_any_congested+0x4a/0x50
Nov 28 07:03:31 server1 kernel: [890070.995581]  [<ffffffff8118feec>] page_cache_async_readahead+0x6c/0x70
Nov 28 07:03:31 server1 kernel: [890070.995584]  [<ffffffff811846a0>] generic_file_read_iter+0x390/0x5c0
Nov 28 07:03:31 server1 kernel: [890070.995586]  [<ffffffff812375e7>] blkdev_read_iter+0x37/0x40
Nov 28 07:03:31 server1 kernel: [890070.995589]  [<ffffffff811fdc55>] new_sync_read+0x85/0xb0
Nov 28 07:03:31 server1 kernel: [890070.995591]  [<ffffffff811fdca7>] __vfs_read+0x27/0x40
Nov 28 07:03:31 server1 kernel: [890070.995593]  [<ffffffff811fe24f>] vfs_read+0x7f/0x130
Nov 28 07:03:31 server1 kernel: [890070.995595]  [<ffffffff811ff026>] SyS_read+0x46/0xa0
Nov 28 07:03:31 server1 kernel: [890070.995597]  [<ffffffff811fdf27>] ? SyS_lseek+0x87/0xb0
Nov 28 07:03:31 server1 kernel: [890070.995599]  [<ffffffff817fe836>] entry_SYSCALL_64_fastpath+0x16/0x75



Nov 28 07:04:29 server4 kernel: [504268.435113] INFO: task blkback.44.xvda:8031 blocked for more than 120 seconds.
Nov 28 07:04:29 server4 kernel: [504268.435173]       Not tainted 4.4.0-47-generic #68~14.04.1-Ubuntu
Nov 28 07:04:29 server4 kernel: [504268.435233] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Nov 28 07:04:29 server4 kernel: [504268.435295] blkback.44.xvda D ffff8801709b7928     0  8031      2 0x00000000
Nov 28 07:04:29 server4 kernel: [504268.435334]  ffff8801709b7928 ffff88017ccf8dc0 ffff880119c30000 ffff8801709b8000
Nov 28 07:04:29 server4 kernel: [504268.435339]  ffff8800047c0c18 ffff8800047c0c00 ffffffff00000000 fffffffe00000001
Nov 28 07:04:29 server4 kernel: [504268.435343]  ffff8801709b7940 ffffffff817fafc5 ffff880119c30000 ffff8801709b79c0
Nov 28 07:04:29 server4 kernel: [504268.435347] Call Trace:
Nov 28 07:04:29 server4 kernel: [504268.435358]  [<ffffffff817fafc5>] schedule+0x35/0x80
Nov 28 07:04:29 server4 kernel: [504268.435362]  [<ffffffff817fd46a>] rwsem_down_write_failed+0x1da/0x320
Nov 28 07:04:29 server4 kernel: [504268.435367]  [<ffffffff813e6a53>] call_rwsem_down_write_failed+0x13/0x20
Nov 28 07:04:29 server4 kernel: [504268.435369]  [<ffffffff817fcd7d>] ? down_write+0x2d/0x40
Nov 28 07:04:29 server4 kernel: [504268.435377]  [<ffffffffc0397dae>] __origin_write+0x6e/0x210 [dm_snapshot]
Nov 28 07:04:29 server4 kernel: [504268.435382]  [<ffffffff81185625>] ? mempool_alloc_slab+0x15/0x20
Nov 28 07:04:29 server4 kernel: [504268.435385]  [<ffffffff8118574f>] ? mempool_alloc+0x5f/0x150
Nov 28 07:04:29 server4 kernel: [504268.435388]  [<ffffffffc0397fb7>] do_origin.isra.14+0x67/0x90 [dm_snapshot]
Nov 28 07:04:29 server4 kernel: [504268.435391]  [<ffffffffc0398042>] origin_map+0x62/0x80 [dm_snapshot]
Nov 28 07:04:29 server4 kernel: [504268.435395]  [<ffffffff8167f2da>] __map_bio+0x3a/0x110
Nov 28 07:04:29 server4 kernel: [504268.435398]  [<ffffffff816809c0>] __split_and_process_bio+0x240/0x3c0
Nov 28 07:04:29 server4 kernel: [504268.435401]  [<ffffffff81680baa>] dm_make_request+0x6a/0xd0
Nov 28 07:04:29 server4 kernel: [504268.435406]  [<ffffffff813aa221>] generic_make_request+0xe1/0x1a0
Nov 28 07:04:29 server4 kernel: [504268.435409]  [<ffffffff813aa357>] submit_bio+0x77/0x150
Nov 28 07:04:29 server4 kernel: [504268.435411]  [<ffffffff813a1c71>] ? bio_alloc_bioset+0x181/0x2a0
Nov 28 07:04:29 server4 kernel: [504268.435417]  [<ffffffffc03a8a1d>] dispatch_rw_block_io+0x4fd/0x9b0 [xen_blkback]
Nov 28 07:04:29 server4 kernel: [504268.435420]  [<ffffffff8101c244>] ? xen_load_sp0+0x84/0x180
Nov 28 07:04:29 server4 kernel: [504268.435423]  [<ffffffffc03a90c5>] __do_block_io_op+0x1f5/0x650 [xen_blkback]
Nov 28 07:04:29 server4 kernel: [504268.435427]  [<ffffffff810e5e18>] ? del_timer_sync+0x48/0x50
Nov 28 07:04:29 server4 kernel: [504268.435429]  [<ffffffff817fd8ab>] ? schedule_timeout+0x16b/0x2d0
Nov 28 07:04:29 server4 kernel: [504268.435432]  [<ffffffffc03a9880>] xen_blkif_schedule+0xd0/0x820 [xen_blkback]
Nov 28 07:04:29 server4 kernel: [504268.435436]  [<ffffffff810a4e1a>] ? finish_task_switch+0x7a/0x290
Nov 28 07:04:29 server4 kernel: [504268.435438]  [<ffffffff817fa969>] ? __schedule+0x359/0x980
Nov 28 07:04:29 server4 kernel: [504268.435443]  [<ffffffff810bde70>] ? prepare_to_wait_event+0xf0/0xf0
Nov 28 07:04:29 server4 kernel: [504268.435446]  [<ffffffffc03a97b0>] ? xen_blkif_be_int+0x30/0x30 [xen_blkback]
Nov 28 07:04:29 server4 kernel: [504268.435449]  [<ffffffff8109ba29>] kthread+0xc9/0xe0
Nov 28 07:04:29 server4 kernel: [504268.435451]  [<ffffffff8109b960>] ? kthread_park+0x60/0x60
Nov 28 07:04:29 server4 kernel: [504268.435455]  [<ffffffff817febcf>] ret_from_fork+0x3f/0x70
Nov 28 07:04:29 server4 kernel: [504268.435457]  [<ffffffff8109b960>] ? kthread_park+0x60/0x60
Nov 28 07:04:29 server4 kernel: [504268.435473] INFO: task kworker/u4:2:10156 blocked for more than 120 seconds.
Nov 28 07:04:29 server4 kernel: [504268.435523]       Not tainted 4.4.0-47-generic #68~14.04.1-Ubuntu
Nov 28 07:04:29 server4 kernel: [504268.435568] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Nov 28 07:04:29 server4 kernel: [504268.435617] kworker/u4:2    D ffff880160633628     0 10156      2 0x00000000
Nov 28 07:04:29 server4 kernel: [504268.435625] Workqueue: writeback wb_workfn (flush-252:36)
Nov 28 07:04:29 server4 kernel: [504268.435627]  ffff880160633628 ffff880007366040 ffff880076470dc0 ffff880160634000
Nov 28 07:04:29 server4 kernel: [504268.435630]  ffff8800047c0c18 ffff8800047c0c00 ffffffff00000000 fffffffe00000001
Nov 28 07:04:29 server4 kernel: [504268.435632]  ffff880160633640 ffffffff817fafc5 ffff880076470dc0 ffff8801606336c0
Nov 28 07:04:29 server4 kernel: [504268.435635] Call Trace:
Nov 28 07:04:29 server4 kernel: [504268.435637]  [<ffffffff817fafc5>] schedule+0x35/0x80
Nov 28 07:04:29 server4 kernel: [504268.435640]  [<ffffffff817fd46a>] rwsem_down_write_failed+0x1da/0x320
Nov 28 07:04:29 server4 kernel: [504268.435642]  [<ffffffff813a1a5c>] ? bvec_alloc+0x5c/0xf0
Nov 28 07:04:29 server4 kernel: [504268.435645]  [<ffffffff813e6a53>] call_rwsem_down_write_failed+0x13/0x20
Nov 28 07:04:29 server4 kernel: [504268.435647]  [<ffffffff817fcd7d>] ? down_write+0x2d/0x40
Nov 28 07:04:29 server4 kernel: [504268.435650]  [<ffffffffc0398d12>] snapshot_map+0x62/0x390 [dm_snapshot]
Nov 28 07:04:29 server4 kernel: [504268.435653]  [<ffffffff8167f2da>] __map_bio+0x3a/0x110
Nov 28 07:04:29 server4 kernel: [504268.435656]  [<ffffffff816809c0>] __split_and_process_bio+0x240/0x3c0
Nov 28 07:04:29 server4 kernel: [504268.435658]  [<ffffffff810c4e11>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
Nov 28 07:04:29 server4 kernel: [504268.435661]  [<ffffffff81680baa>] dm_make_request+0x6a/0xd0
Nov 28 07:04:29 server4 kernel: [504268.435664]  [<ffffffff813aa221>] generic_make_request+0xe1/0x1a0
Nov 28 07:04:29 server4 kernel: [504268.435667]  [<ffffffff813aa357>] submit_bio+0x77/0x150
Nov 28 07:04:29 server4 kernel: [504268.435669]  [<ffffffff813a1c71>] ? bio_alloc_bioset+0x181/0x2a0
Nov 28 07:04:29 server4 kernel: [504268.435673]  [<ffffffff812347ef>] submit_bh_wbc+0x12f/0x160
Nov 28 07:04:29 server4 kernel: [504268.435675]  [<ffffffff81236615>] __block_write_full_page.constprop.39+0x125/0x360
Nov 28 07:04:29 server4 kernel: [504268.435677]  [<ffffffff81236af0>] ? I_BDEV+0x20/0x20
Nov 28 07:04:29 server4 kernel: [504268.435679]  [<ffffffff8123692e>] block_write_full_page+0xde/0x100
Nov 28 07:04:29 server4 kernel: [504268.435682]  [<ffffffff81237378>] blkdev_writepage+0x18/0x20
Nov 28 07:04:29 server4 kernel: [504268.435684]  [<ffffffff8118d253>] __writepage+0x13/0x40
Nov 28 07:04:29 server4 kernel: [504268.435687]  [<ffffffff8118e5c1>] write_cache_pages+0x241/0x4c0
Nov 28 07:04:29 server4 kernel: [504268.435689]  [<ffffffff8118d240>] ? wb_update_dirty_ratelimit+0x1c0/0x1c0
Nov 28 07:04:29 server4 kernel: [504268.435692]  [<ffffffff817fe23a>] ? _raw_spin_unlock_irqrestore+0x1a/0x20
Nov 28 07:04:29 server4 kernel: [504268.435701]  [<ffffffffc0126226>] ? _base_get_chain_buffer_tracker+0x86/0xd0 [mpt3sas]
Nov 28 07:04:29 server4 kernel: [504268.435703]  [<ffffffff8118e883>] generic_writepages+0x43/0x60
Nov 28 07:04:29 server4 kernel: [504268.435706]  [<ffffffff8118f46e>] do_writepages+0x1e/0x30
Nov 28 07:04:29 server4 kernel: [504268.435708]  [<ffffffff8122b215>] __writeback_single_inode+0x45/0x340
Nov 28 07:04:29 server4 kernel: [504268.435710]  [<ffffffff8122ba4b>] writeback_sb_inodes+0x26b/0x5c0
Nov 28 07:04:29 server4 kernel: [504268.435713]  [<ffffffff8122be26>] __writeback_inodes_wb+0x86/0xc0
Nov 28 07:04:29 server4 kernel: [504268.435715]  [<ffffffff8122c0b2>] wb_writeback+0x252/0x2e0
Nov 28 07:04:29 server4 kernel: [504268.435717]  [<ffffffff8122c8a2>] wb_workfn+0x2c2/0x3d0
Nov 28 07:04:29 server4 kernel: [504268.435719]  [<ffffffff810c4e11>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
Nov 28 07:04:29 server4 kernel: [504268.435724]  [<ffffffff81095b40>] process_one_work+0x150/0x3f0
Nov 28 07:04:29 server4 kernel: [504268.435727]  [<ffffffff810962ba>] worker_thread+0x11a/0x470
Nov 28 07:04:29 server4 kernel: [504268.435729]  [<ffffffff817fa969>] ? __schedule+0x359/0x980
Nov 28 07:04:29 server4 kernel: [504268.435732]  [<ffffffff810961a0>] ? rescuer_thread+0x310/0x310
Nov 28 07:04:29 server4 kernel: [504268.435734]  [<ffffffff8109ba29>] kthread+0xc9/0xe0
Nov 28 07:04:29 server4 kernel: [504268.435736]  [<ffffffff8109b960>] ? kthread_park+0x60/0x60
Nov 28 07:04:29 server4 kernel: [504268.435739]  [<ffffffff817febcf>] ret_from_fork+0x3f/0x70
Nov 28 07:04:29 server4 kernel: [504268.435741]  [<ffffffff8109b960>] ? kthread_park+0x60/0x60
Nov 28 07:04:29 server4 kernel: [504268.435750] INFO: task fsck.ext4:17037 blocked for more than 120 seconds.
Nov 28 07:04:29 server4 kernel: [504268.435797]       Not tainted 4.4.0-47-generic #68~14.04.1-Ubuntu
Nov 28 07:04:29 server4 kernel: [504268.435842] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Nov 28 07:04:29 server4 kernel: [504268.435890] fsck.ext4       D ffff88016b6a7888     0 17037  17035 0x00000000
Nov 28 07:04:29 server4 kernel: [504268.435893]  ffff88016b6a7888 ffff880004569b80 ffff880010cb1b80 ffff88016b6a8000
Nov 28 07:04:29 server4 kernel: [504268.435895]  ffff8800047c0c18 ffff8800047c0c00 ffffffff00000000 fffffffe00000001
Nov 28 07:04:29 server4 kernel: [504268.435898]  ffff88016b6a78a0 ffffffff817fafc5 ffff880010cb1b80 ffff88016b6a7918
Nov 28 07:04:29 server4 kernel: [504268.435901] Call Trace:
Nov 28 07:04:29 server4 kernel: [504268.435903]  [<ffffffff817fafc5>] schedule+0x35/0x80
Nov 28 07:04:29 server4 kernel: [504268.435905]  [<ffffffff817fd46a>] rwsem_down_write_failed+0x1da/0x320
Nov 28 07:04:29 server4 kernel: [504268.435908]  [<ffffffff813e6a53>] call_rwsem_down_write_failed+0x13/0x20
Nov 28 07:04:29 server4 kernel: [504268.435910]  [<ffffffff817fcd7d>] ? down_write+0x2d/0x40
Nov 28 07:04:29 server4 kernel: [504268.435913]  [<ffffffffc0398d12>] snapshot_map+0x62/0x390 [dm_snapshot]
Nov 28 07:04:29 server4 kernel: [504268.435916]  [<ffffffff8167f2da>] __map_bio+0x3a/0x110
Nov 28 07:04:29 server4 kernel: [504268.435919]  [<ffffffff816809c0>] __split_and_process_bio+0x240/0x3c0
Nov 28 07:04:29 server4 kernel: [504268.435921]  [<ffffffff81680baa>] dm_make_request+0x6a/0xd0
Nov 28 07:04:29 server4 kernel: [504268.435924]  [<ffffffff813aa221>] generic_make_request+0xe1/0x1a0
Nov 28 07:04:29 server4 kernel: [504268.435927]  [<ffffffff813aa357>] submit_bio+0x77/0x150
Nov 28 07:04:29 server4 kernel: [504268.435930]  [<ffffffff8123cf6a>] mpage_bio_submit+0x2a/0x40
Nov 28 07:04:29 server4 kernel: [504268.435932]  [<ffffffff8123d8f4>] mpage_readpages+0x134/0x150
Nov 28 07:04:29 server4 kernel: [504268.435934]  [<ffffffff81236af0>] ? I_BDEV+0x20/0x20
Nov 28 07:04:29 server4 kernel: [504268.435936]  [<ffffffff81236af0>] ? I_BDEV+0x20/0x20
Nov 28 07:04:29 server4 kernel: [504268.435938]  [<ffffffff8123733d>] blkdev_readpages+0x1d/0x20
Nov 28 07:04:29 server4 kernel: [504268.435940]  [<ffffffff8118fb94>] __do_page_cache_readahead+0x174/0x200
Nov 28 07:04:29 server4 kernel: [504268.435943]  [<ffffffff8118fd55>] ondemand_readahead+0x135/0x260
Nov 28 07:04:29 server4 kernel: [504268.435945]  [<ffffffff8168033a>] ? dm_any_congested+0x4a/0x50
Nov 28 07:04:29 server4 kernel: [504268.435948]  [<ffffffff8118feec>] page_cache_async_readahead+0x6c/0x70
Nov 28 07:04:29 server4 kernel: [504268.435951]  [<ffffffff811846a0>] generic_file_read_iter+0x390/0x5c0
Nov 28 07:04:29 server4 kernel: [504268.435953]  [<ffffffff812375e7>] blkdev_read_iter+0x37/0x40
Nov 28 07:04:29 server4 kernel: [504268.435957]  [<ffffffff811fdc55>] new_sync_read+0x85/0xb0
Nov 28 07:04:29 server4 kernel: [504268.435959]  [<ffffffff811fdca7>] __vfs_read+0x27/0x40
Nov 28 07:04:29 server4 kernel: [504268.435961]  [<ffffffff811fe24f>] vfs_read+0x7f/0x130
Nov 28 07:04:29 server4 kernel: [504268.435964]  [<ffffffff811ff026>] SyS_read+0x46/0xa0
Nov 28 07:04:29 server4 kernel: [504268.435966]  [<ffffffff811fdf27>] ? SyS_lseek+0x87/0xb0
Nov 28 07:04:29 server4 kernel: [504268.435969]  [<ffffffff817fe836>] entry_SYSCALL_64_fastpath+0x16/0x75