INFO: task loop0:5662 blocked for more than 120 seconds.
      Not tainted 4.9.110-g00a0bcb #56
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
loop0           D27080  5662      2 0x00000000
 ffff880183fa9800 ffff8801ccd9f9c0 ffff8801bd496a00 ffff8801ccb50000
 ffff8801db321c18 ffff8801cce66df0 ffffffff839e6ded 0000000041b58ab3
 ffffffff843c30c8 ffffffff81236160 0000000000000000 ffff8801db3224e8
Call Trace:
 [<ffffffff839e83ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f4801>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839e65ca>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180
 [<ffffffff81e5040c>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff81e5040c>] bt_get.isra.8+0x27c/0x780 block/blk-mq-tag.c:141
 [<ffffffff81e5131c>] __blk_mq_get_tag block/blk-mq-tag.c:163 [inline]
 [<ffffffff81e5131c>] blk_mq_get_tag+0xac/0x220 block/blk-mq-tag.c:192
 [<ffffffff81e40a4a>] __blk_mq_alloc_request+0x2a/0xaa0 block/blk-mq.c:196
 [<ffffffff81e42e4b>] blk_mq_map_request.isra.38+0x3ab/0x900 block/blk-mq.c:1207
 [<ffffffff81e4b296>] blk_sq_make_request+0x1d6/0x1220 block/blk-mq.c:1374
 [<ffffffff81e1e1ce>] generic_make_request+0x20e/0x9b0 block/blk-core.c:2055
 [<ffffffff81e1ea20>] submit_bio+0xb0/0x460 block/blk-core.c:2126
 [<ffffffff8164390a>] dio_bio_submit fs/direct-io.c:420 [inline]
 [<ffffffff8164390a>] do_blockdev_direct_IO+0x35da/0x5a80 fs/direct-io.c:1301
 [<ffffffff81645e55>] __blockdev_direct_IO+0xa5/0xd0 fs/direct-io.c:1360
 [<ffffffff8162fa00>] blkdev_direct_IO+0xa0/0xd0 fs/block_dev.c:183
 [<ffffffff8143e740>] generic_file_read_iter+0x660/0x1a90 mm/filemap.c:1951
 [<ffffffff81632605>] blkdev_read_iter+0x105/0x170 fs/block_dev.c:1738
 [<ffffffff825cc4a3>] lo_rw_aio+0x6b3/0x8a0 drivers/block/loop.c:506
 [<ffffffff825cca67>] do_req_filebacked drivers/block/loop.c:543 [inline]
 [<ffffffff825cca67>] loop_handle_cmd drivers/block/loop.c:1698 [inline]
 [<ffffffff825cca67>] loop_queue_work+0x3d7/0x2320 drivers/block/loop.c:1710
 [<ffffffff8119d429>] kthread_worker_fn+0x249/0x6b0 kernel/kthread.c:627
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f7e9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425cb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3738:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f5e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8211e1e2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor0/3809:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor7/7742:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor7/7743:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor7/7745:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor7/7750:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor7/7754:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor7/7756:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor1/7708:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor1/7746:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.110-g00a0bcb #56
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d841fd08 ffffffff81eb2329 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9580 ffff8801d841fd40
 ffffffff81ebd627 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb2329>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb2329>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebd627>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebd5ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9684>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366bc4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366bc4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366bc4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366bc4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f7e9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3640 Comm: rs:main Q:Reg Not tainted 4.9.110-g00a0bcb #56
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801be730000 task.stack: ffff8801be248000
RIP: 0010:[<ffffffff817547ef>] 
c [<ffffffff817547ef>] ext4_truncate+0xa2f/0x12c0 fs/ext4/inode.c:4265
RSP: 0018:ffff8801be24f648  EFLAGS: 00000257
RAX: dffffc0000000000 RBX: ffff8801bbee52e0 RCX: ffff8801be730000
RDX: ffff8801bbee5308 RSI: 0000000000000005 RDI: ffff8801bbee5238
RBP: ffff8801be24f700 R08: ffff8801be7309b0 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff10037c49ecf
R13: ffff8801d631c600 R14: ffff8801bbee5308 R15: ffff8801bbee51e0
FS:  00007fe0b8463700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3d65433000 CR3: 00000001c31c3000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000000
c 0000000000000000
c 0000000000000000
c ffff8801bbee54d8
c
 ffff8801bbee5140
c ffff8801bbee5330
c 0000000041b58ab3
c ffffffff843d7589
c
 ffffffff81753dc0
c ffff8801bbee52e0
c ffff8801be24f6d8
c 0000000000000000
c
Call Trace:
 [<ffffffff8175696b>] ext4_truncate_failed_write fs/ext4/truncate.h:15 [inline]
 [<ffffffff8175696b>] ext4_da_write_begin+0x4eb/0x1020 fs/ext4/inode.c:3015
 [<ffffffff81435c91>] generic_perform_write+0x301/0x510 mm/filemap.c:2740
 [<ffffffff8143d722>] __generic_file_write_iter+0x352/0x540 mm/filemap.c:2865
 [<ffffffff8172cec3>] ext4_file_write_iter+0x463/0xd90 fs/ext4/file.c:165
 [<ffffffff8156eb60>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff8156eb60>] __vfs_write+0x3e0/0x580 fs/read_write.c:509
 [<ffffffff81572957>] vfs_write+0x187/0x530 fs/read_write.c:557
 [<ffffffff81576789>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff81576789>] SyS_write+0xd9/0x1c0 fs/read_write.c:596
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f7cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c