Buffer I/O error on dev loop0, logical block 3, lost async page write
INFO: task syz-executor4:9108 blocked for more than 120 seconds.
      Not tainted 4.9.78-g7be1985 #24
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D27200  9108   4150 0x00000004
 ffff8801c3a44800 0000000000000000 ffff8801c9e05500 ffff8801d9b41800
 ffff8801db321b98 ffff8801c67d72c0 ffffffff838a1bbb 0000000041b58ab3
 ffffffff84193238 00ffffff8123be70 ffff8801db322468 ffff8801db322490
Call Trace:
 [<ffffffff838a315f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838af2bc>] schedule_timeout+0x56c/0x10b0 kernel/time/timer.c:1768
 [<ffffffff838a136e>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5172
 [<ffffffff838a45d9>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838a45d9>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838a3cb7>] __wait_on_bit+0x57/0x120 kernel/sched/wait.c:383
 [<ffffffff81432534>] wait_on_page_bit+0xf4/0x140 mm/filemap.c:802
 [<ffffffff81432741>] wait_on_page_writeback include/linux/pagemap.h:526 [inline]
 [<ffffffff81432741>] __filemap_fdatawait_range+0x1c1/0x2b0 mm/filemap.c:453
 [<ffffffff81432855>] filemap_fdatawait_range+0x25/0x50 mm/filemap.c:483
 [<ffffffff8143b594>] filemap_write_and_wait_range+0x74/0xb0 mm/filemap.c:584
 [<ffffffff81629ff6>] blkdev_fsync+0x66/0xb0 fs/block_dev.c:369
 [<ffffffff8161597a>] vfs_fsync_range+0x10a/0x250 fs/sync.c:195
 [<ffffffff8162cbc6>] generic_write_sync include/linux/fs.h:2588 [inline]
 [<ffffffff8162cbc6>] blkdev_write_iter+0x2a6/0x380 fs/block_dev.c:1720
 [<ffffffff8156d8f0>] vfs_iter_write+0x2e0/0x450 fs/read_write.c:393
 [<ffffffff816128f5>] iter_file_splice_write+0x5b5/0xb60 fs/splice.c:768
 [<ffffffff8160d735>] do_splice_from fs/splice.c:870 [inline]
 [<ffffffff8160d735>] direct_splice_actor+0x125/0x180 fs/splice.c:1037
 [<ffffffff8160ecfc>] splice_direct_to_actor+0x2cc/0x800 fs/splice.c:992
 [<ffffffff8160f3d7>] do_splice_direct+0x1a7/0x270 fs/splice.c:1080
 [<ffffffff8157258b>] do_sendfile+0x54b/0xd30 fs/read_write.c:1401
 [<ffffffff815744e1>] SYSC_sendfile64 fs/read_write.c:1456 [inline]
 [<ffffffff815744e1>] SyS_sendfile64+0xd1/0x160 fs/read_write.c:1448
 [<ffffffff838b2c6e>] entry_SYSCALL_64_fastpath+0x29/0xe8

Showing all locks held in the system:
2 locks held by khungtaskd/514:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81372e45>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81372e45>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81237fd0>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
2 locks held by getty/4041:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838b0e32>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82009754>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:5/5755:
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189722>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189722>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189722>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189722>] process_one_work+0x6f2/0x1610 kernel/workqueue.c:2085
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff8118975c>] process_one_work+0x72c/0x1610 kernel/workqueue.c:2089
 #2:  (&type->s_umount_key#22){.+.+..}, at: [<ffffffff81579610>] trylock_super+0x20/0x100 fs/super.c:393

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

NMI backtrace for cpu 1
CPU: 1 PID: 514 Comm: khungtaskd Not tainted 4.9.78-g7be1985 #24
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d870fd00 ffffffff81d94409 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810bac10 ffff8801d870fd38
 ffffffff81d9f52d 0000000000000001 0000000000000000 ffff8801c2b16418
Call Trace:
 [<ffffffff81d94409>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d94409>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9f52d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9f667>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810bad04>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81373410>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81373410>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81373410>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81373410>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119a72d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b2fdc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:477
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.78-g7be1985 #24
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84429880 task.stack: ffffffff84400000
RIP: 0010:[<ffffffff8123c26c>] 
c [<ffffffff8123c26c>] __lock_acquire+0x3fc/0x3640 kernel/locking/lockdep.c:3290
RSP: 0018:ffff8801db207c20  EFLAGS: 00000002
RAX: 0000000000000000 RBX: ffffffff8442a130 RCX: 0000000000000000
RDX: 0000000000000002 RSI: 0000000000000000 RDI: ffffffff8442a154
RBP: ffff8801db207dd8 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: ffffffff84429880 R12: 000000000000003a
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efdfcd7e000 CR3: 00000001b56f2000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000041b58ab3
c ffffffff84193238
c ffffffff8123be70
c 0000000000000000
c
 ffffffff84429880
c ffffffff8442a130
c 0000000000000038
c 0000000000000040
c
 0000000000000000
c 0000000000000002
c ffff8801db207e38
c 0000000000000046
c
Call Trace:
 [<ffffffff8123feee>] lock_acquire+0x12e/0x410 kernel/locking/lockdep.c:3756
 [<ffffffff838b2026>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
 [<ffffffff838b2026>] _raw_spin_lock+0x36/0x50 kernel/locking/spinlock.c:151
 [<ffffffff812acec7>] spin_lock include/linux/spinlock.h:302 [inline]
 [<ffffffff812acec7>] get_next_timer_interrupt+0x77/0x2b0 kernel/time/timer.c:1529
 [<ffffffff812d91dd>] tick_nohz_stop_sched_tick kernel/time/tick-sched.c:708 [inline]
 [<ffffffff812d91dd>] __tick_nohz_idle_enter+0x91d/0x1180 kernel/time/tick-sched.c:936
 [<ffffffff812da3e8>] tick_nohz_irq_exit+0x78/0xa0 kernel/time/tick-sched.c:995
 [<ffffffff81146bd1>] tick_irq_exit kernel/softirq.c:386 [inline]
 [<ffffffff81146bd1>] irq_exit+0x151/0x190 kernel/softirq.c:407
 [<ffffffff838b74eb>] smp_reschedule_interrupt+0x6b/0x80 arch/x86/kernel/smp.c:267
 [<ffffffff838b5100>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:775
 <EOI> 
d [<ffffffff838b18a6>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff838b0ed5>] arch_safe_halt arch/x86/include/asm/paravirt.h:103 [inline]
 [<ffffffff838b0ed5>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff8106bc9a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:286
 [<ffffffff838b1ce6>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97
 [<ffffffff812265d0>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff812265d0>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff812265d0>] cpu_startup_entry+0x2b0/0x380 kernel/sched/idle.c:303
 [<ffffffff8389e804>] rest_init+0x184/0x190 init/main.c:408
 [<ffffffff84a6f8b6>] start_kernel+0x688/0x6bd init/main.c:663
 [<ffffffff84a6e29d>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84a6e3df>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:177
Code: 
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