INFO: task blkid:6902 blocked for more than 120 seconds.
      Not tainted 4.4.120-gd63fdf6 #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid           D ffff8801d6fdf370 26408  6902   2310 0x00000006
 ffff8801d6fdf370 ffff8801d72668f8 0000000000000024 ffff8801d7266000
 ffffffff842bdbe0 0000000000000000 ffff8801db31fdb8 ffff8801db31fde0
 ffff8801db31f4d8 ffff8801d9b49800 ffff8801d7266000 0000000000000000
Call Trace:
 [<ffffffff8376582a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3353
 [<ffffffff83770b40>] schedule_timeout+0x3a0/0x970 kernel/time/timer.c:1515
 [<ffffffff837637be>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:4935
 [<ffffffff83766aeb>] io_schedule include/linux/sched.h:447 [inline]
 [<ffffffff83766aeb>] bit_wait_io+0x1b/0xc0 kernel/sched/wait.c:595
 [<ffffffff8376662f>] __wait_on_bit_lock+0x8f/0x140 kernel/sched/wait.c:434
 [<ffffffff8141ddad>] __lock_page+0x18d/0x1f0 mm/filemap.c:888
 [<ffffffff8144da87>] lock_page include/linux/pagemap.h:458 [inline]
 [<ffffffff8144da87>] truncate_inode_pages_range+0x8e7/0xe70 mm/truncate.c:362
 [<ffffffff8144e034>] truncate_inode_pages+0x24/0x30 mm/truncate.c:390
 [<ffffffff815cfc7c>] kill_bdev+0xbc/0xf0 fs/block_dev.c:82
 [<ffffffff815d31d1>] __blkdev_put+0x191/0x7e0 fs/block_dev.c:1523
 [<ffffffff815d4695>] blkdev_put+0x85/0x550 fs/block_dev.c:1600
 [<ffffffff815d4beb>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1607
 [<ffffffff81523603>] __fput+0x233/0x6d0 fs/file_table.c:208
 [<ffffffff81523b25>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118b984>] task_work_run+0x104/0x180 kernel/task_work.c:115
 [<ffffffff81132f2a>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81132f2a>] do_exit+0x82a/0x2a10 kernel/exit.c:755
 [<ffffffff811393c8>] do_group_exit+0x108/0x320 kernel/exit.c:885
 [<ffffffff8115c822>] get_signal+0x4f2/0x1550 kernel/signal.c:2317
 [<ffffffff8100e7fb>] do_signal+0x8b/0x1d40 arch/x86/kernel/signal.c:712
 [<ffffffff810035fa>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:248
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348
 [<ffffffff83773ae9>] int_ret_from_sys_call+0x25/0xa3
1 lock held by blkid/6902:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815d30fc>] __blkdev_put+0xbc/0x7e0 fs/block_dev.c:1516
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.120-gd63fdf6 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84217840 task.stack: ffffffff84200000
RIP: 0010:[<ffffffff812acea0>]  [<ffffffff812acea0>] hrtimer_try_to_cancel+0x0/0x660 kernel/time/hrtimer.c:601
RSP: 0018:ffffffff84207da0  EFLAGS: 00000093
RAX: ffffffff84217840 RBX: ffff8801db219c40 RCX: ffffffff812ad51a
RDX: 0000000000000000 RSI: 000000382ce8599e RDI: ffff8801db219c40
RBP: ffffffff84207db8 R08: 1ffffffff0883068 R09: 0000000000000001
R10: 0000000000000000 R11: dffffc0000000000 R12: ffff8801db219cb4
R13: 0000000000000001 R14: 000000382ce8599e R15: ffffffff84208000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001d2c000 CR3: 00000000b6688000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff812ad522 ffffffff84208000 ffff8801db219c40 ffffffff84207de8
 ffffffff812d581e ffff8801db219c40 ffff8801db219cb4 0000000000000001
 000000382ce8599e ffffffff84207e20 ffffffff812d7877 ffffffff84207e10
Call Trace:
 [<ffffffff812d581e>] tick_nohz_restart+0x1e/0x190 kernel/time/tick-sched.c:559
 [<ffffffff812d7877>] tick_nohz_restart_sched_tick kernel/time/tick-sched.c:726 [inline]
 [<ffffffff812d7877>] tick_nohz_idle_exit+0x247/0x3d0 kernel/time/tick-sched.c:946
 [<ffffffff81221815>] cpu_idle_loop kernel/sched/idle.c:267 [inline]
 [<ffffffff81221815>] cpu_startup_entry+0x2a5/0x8f0 kernel/sched/idle.c:301
 [<ffffffff837608b9>] rest_init+0x189/0x190 init/main.c:410
 [<ffffffff84822811>] start_kernel+0x6b9/0x6ee init/main.c:682
 [<ffffffff84821312>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84821454>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:185
Code: 4c 89 e7 48 89 45 e8 e8 bf 19 25 00 48 8b 45 e8 eb 8c 4c 89 e7 e8 11 19 25 00 eb a8 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 <55> 48 89 e5 41 57 49 bf 00 00 00 00 00 fc ff df 41 56 45 31 f6 
NMI backtrace for cpu 1
CPU: 1 PID: 485 Comm: khungtaskd Not tainted 4.4.120-gd63fdf6 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bb2be000 task.stack: ffff8800bb248000
RIP: 0010:[<ffffffff810c3e67>]  [<ffffffff810c3e67>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3e67>]  [<ffffffff810c3e67>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3e67>]  [<ffffffff810c3e67>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3e67>]  [<ffffffff810c3e67>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bb24fcb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bb24fce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426f420 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc8f6ff49b8 CR3: 00000000b6688000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f420 ffffffff847efb00 fffffbfff08fda14 dffffc0000000000
 ffff8801db31bca0 ffff8800bb24fd00 ffffffff810b999b ffffffff839f63c0
 0000000000000003 ffff8800bb24fd60 ffffffff81d0eff4 ffffffff8141b053
Call Trace:
 [<ffffffff810b999b>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d0eff4>] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9a34>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff81368c9a>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff81368c9a>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81368c9a>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81368c9a>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff81190788>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff83773d85>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:506
Code: b3 5f ff f6 c4 10 75 e1 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 74 1a e8 6b 2f 17 00 4c 89 e7 57 9d 0f 1f