INFO: task loop0:4175 blocked for more than 120 seconds.
      Not tainted 4.9.109-ge1815b3 #3
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
loop0           D27080  4175      2 0x00000000
 ffff8801d0281800 ffff8801cfa5ea00 ffff8801cfa5ea00 ffff8801cf9d8000
 ffff8801db221c18 ffff8801cf63edf0 ffffffff839e8a8d 0000000041b58ab3
 ffffffff843c2288 ffffffff81236160 0000000000000000 ffff8801db2224e8
Call Trace:
 [<ffffffff839ea08f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f64a1>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839e826a>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180
 [<ffffffff81e51f0c>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff81e51f0c>] bt_get.isra.8+0x27c/0x780 block/blk-mq-tag.c:141
 [<ffffffff81e52e1c>] __blk_mq_get_tag block/blk-mq-tag.c:163 [inline]
 [<ffffffff81e52e1c>] blk_mq_get_tag+0xac/0x220 block/blk-mq-tag.c:192
 [<ffffffff81e4254a>] __blk_mq_alloc_request+0x2a/0xaa0 block/blk-mq.c:196
 [<ffffffff81e4494b>] blk_mq_map_request.isra.38+0x3ab/0x900 block/blk-mq.c:1207
 [<ffffffff81e4cd96>] blk_sq_make_request+0x1d6/0x1220 block/blk-mq.c:1374
 [<ffffffff81e1fcce>] generic_make_request+0x20e/0x9b0 block/blk-core.c:2055
 [<ffffffff81e20520>] 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
 [<ffffffff825cdf13>] lo_rw_aio+0x6b3/0x8a0 drivers/block/loop.c:506
 [<ffffffff825ce4d7>] do_req_filebacked drivers/block/loop.c:543 [inline]
 [<ffffffff825ce4d7>] loop_handle_cmd drivers/block/loop.c:1698 [inline]
 [<ffffffff825ce4d7>] 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
 [<ffffffff839f9b5c>] 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/3650:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7b32>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211fce2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.109-ge1815b3 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8677d08 ffffffff81eb3e29 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9580 ffff8801d8677d40
 ffffffff81ebf127 0000000000000000 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb3e29>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3e29>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf127>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf0ba>] 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
 [<ffffffff839f9b5c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3800 Comm: syz-executor0 Not tainted 4.9.109-ge1815b3 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d6f96000 task.stack: ffff8801d80a8000
RIP: 0010:[<ffffffff811f8abb>] 
c [<ffffffff811f8abb>] select_task_rq_fair+0x3ab/0x3dd0 kernel/sched/fair.c:7204
RSP: 0018:ffff8801db307af0  EFLAGS: 00000046
RAX: 00000000000012af RBX: 0000000000000001 RCX: 0000000000000000
RDX: 1ffff1003b338ada RSI: ffffffff846defa0 RDI: ffff8801d99c56d0
RBP: ffff8801db307c18 R08: ffff8801d6f96988 R09: 0000000000000001
R10: ffff8801d6f96000 R11: 1ffff1003adf2d2c R12: ffff8801d99c5680
R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000084e7900
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000ffbaa000 CR3: 00000001d78cf000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff811f89ca
c ffff8801d6f96958
c ffff8801d6f968b8
c ffff8801d6f96960
c
 ffff8801d6f968c0
c ffff8801d6f968c8
c ffff8801db321c18
c dffffc0000000000
c
 ffff8801d6f96968
c ffff8801d6f96940
c 0000000000000004
c ffff8801db307c00
c
Call Trace:
 [<ffffffff811cea9b>] select_task_rq kernel/sched/core.c:1624 [inline]
 [<ffffffff811cea9b>] try_to_wake_up+0x40b/0xec0 kernel/sched/core.c:2121
 [<ffffffff811cf560>] wake_up_process+0x10/0x20 kernel/sched/core.c:2205
 [<ffffffff81298785>] process_timeout+0x15/0x20 kernel/time/timer.c:1724
 [<ffffffff812988f3>] call_timer_fn+0x163/0x6e0 kernel/time/timer.c:1319
 [<ffffffff8129fa57>] expire_timers kernel/time/timer.c:1359 [inline]
 [<ffffffff8129fa57>] __run_timers kernel/time/timer.c:1658 [inline]
 [<ffffffff8129fa57>] run_timer_softirq+0x1047/0x1590 kernel/time/timer.c:1684
 [<ffffffff83a0057b>] __do_softirq+0x20b/0x937 kernel/softirq.c:284
 [<ffffffff8114b227>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff8114b227>] irq_exit+0x147/0x190 kernel/softirq.c:405
 [<ffffffff839ff161>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
 [<ffffffff839ff161>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:960
 [<ffffffff839fb2f0>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> 
d [<ffffffff81450d4f>] ? arch_local_irq_restore arch/x86/include/asm/paravirt.h:768 [inline]
 <EOI> 
d [<ffffffff81450d4f>] ? buffered_rmqueue mm/page_alloc.c:2692 [inline]
 <EOI> 
d [<ffffffff81450d4f>] ? get_page_from_freelist+0xcbf/0x1a00 mm/page_alloc.c:2999
 [<ffffffff81454647>] __alloc_pages_nodemask+0x237/0x700 mm/page_alloc.c:3844
 [<ffffffff814fde94>] __alloc_pages include/linux/gfp.h:433 [inline]
 [<ffffffff814fde94>] __alloc_pages_node include/linux/gfp.h:446 [inline]
 [<ffffffff814fde94>] alloc_pages_node include/linux/gfp.h:460 [inline]
 [<ffffffff814fde94>] __vmalloc_area_node mm/vmalloc.c:1643 [inline]
 [<ffffffff814fde94>] __vmalloc_node_range+0x254/0x5f0 mm/vmalloc.c:1701
 [<ffffffff814fe2fb>] __vmalloc_node mm/vmalloc.c:1744 [inline]
 [<ffffffff814fe2fb>] __vmalloc_node_flags mm/vmalloc.c:1758 [inline]
 [<ffffffff814fe2fb>] vmalloc+0x5b/0x70 mm/vmalloc.c:1773
 [<ffffffff832795ee>] xt_compat_add_offset+0x21e/0x370 net/netfilter/x_tables.c:504
 [<ffffffff834ba0d5>] compat_calc_entry net/ipv4/netfilter/ip_tables.c:926 [inline]
 [<ffffffff834ba0d5>] compat_table_info+0x225/0x470 net/ipv4/netfilter/ip_tables.c:957
 [<ffffffff834be0e8>] compat_get_entries net/ipv4/netfilter/ip_tables.c:1641 [inline]
 [<ffffffff834be0e8>] compat_do_ipt_get_ctl+0x2f8/0x8e0 net/ipv4/netfilter/ip_tables.c:1673
 [<ffffffff831df13e>] compat_nf_sockopt net/netfilter/nf_sockopt.c:138 [inline]
 [<ffffffff831df13e>] compat_nf_getsockopt+0x8e/0x130 net/netfilter/nf_sockopt.c:162
 [<ffffffff833458f8>] compat_ip_getsockopt+0x148/0x1c0 net/ipv4/ip_sockglue.c:1587
 [<ffffffff833525a7>] inet_csk_compat_getsockopt+0x97/0x120 net/ipv4/inet_connection_sock.c:901
 [<ffffffff8336520d>] compat_tcp_getsockopt+0x3d/0x70 net/ipv4/tcp.c:3117
 [<ffffffff8301d444>] compat_sock_common_getsockopt+0xb4/0x150 net/core/sock.c:2676
 [<ffffffff8311d118>] C_SYSC_getsockopt net/compat.c:520 [inline]
 [<ffffffff8311d118>] compat_SyS_getsockopt net/compat.c:503 [inline]
 [<ffffffff8311d118>] C_SYSC_socketcall net/compat.c:854 [inline]
 [<ffffffff8311d118>] compat_SyS_socketcall+0x878/0xb50 net/compat.c:785
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff839fb090>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
Code: 
c00 
cfc 
cff 
cdf 
c48 
c89 
cfa 
c48 
cc1 
cea 
c03 
c0f 
cb6 
c04 
c02 
c84 
cc0 
c74 
c08 
c3c 
c03 
c0f 
c8e 
ce1 
c37 
c00 
c00 
c41 
c8b 
c44 
c24 
c50 
ca8 
c01 
c0f 
c84 
c61 
c05 
c00 
c00 
c45 
c31 
cff 
c<8b> 
c95 
c40 
cff 
cff 
cff 
c49 
cbe 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
ceb 
c64 
ca8 
c20 
c74 
c