Buffer I/O error on dev loop0, logical block 7, async page read
INFO: task syz-executor5:18514 blocked for more than 120 seconds.
      Not tainted 4.9.78-gf518fe4 #22
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor5   D26832 18514   3401 0x00000004
 ffff8801d5643000 0000000000000000 ffff8801d6139f80 ffffffff84429880
 ffff8801db221b98 ffff8801d4fe72c0 ffffffff838a1bbb 0000000041b58ab3
 ffffffff84193238 00ffffff8123be20 ffff8801db222468 ffff8801db222490
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
 [<ffffffff814324e4>] wait_on_page_bit+0xf4/0x140 mm/filemap.c:802
 [<ffffffff814326f1>] wait_on_page_writeback include/linux/pagemap.h:526 [inline]
 [<ffffffff814326f1>] __filemap_fdatawait_range+0x1c1/0x2b0 mm/filemap.c:453
 [<ffffffff81432805>] filemap_fdatawait_range+0x25/0x50 mm/filemap.c:483
 [<ffffffff8143b544>] filemap_write_and_wait_range+0x74/0xb0 mm/filemap.c:584
 [<ffffffff81629fa6>] blkdev_fsync+0x66/0xb0 fs/block_dev.c:369
 [<ffffffff8161592a>] vfs_fsync_range+0x10a/0x250 fs/sync.c:195
 [<ffffffff8162cb76>] generic_write_sync include/linux/fs.h:2588 [inline]
 [<ffffffff8162cb76>] blkdev_write_iter+0x2a6/0x380 fs/block_dev.c:1720
 [<ffffffff8156d8a0>] vfs_iter_write+0x2e0/0x450 fs/read_write.c:393
 [<ffffffff816128a5>] iter_file_splice_write+0x5b5/0xb60 fs/splice.c:768
 [<ffffffff8160d6e5>] do_splice_from fs/splice.c:870 [inline]
 [<ffffffff8160d6e5>] direct_splice_actor+0x125/0x180 fs/splice.c:1037
 [<ffffffff8160ecac>] splice_direct_to_actor+0x2cc/0x800 fs/splice.c:992
 [<ffffffff8160f387>] do_splice_direct+0x1a7/0x270 fs/splice.c:1080
 [<ffffffff8157253b>] do_sendfile+0x54b/0xd30 fs/read_write.c:1401
 [<ffffffff81574491>] SYSC_sendfile64 fs/read_write.c:1456 [inline]
 [<ffffffff81574491>] 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: [<ffffffff81372df5>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81372df5>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.?..}, at: [<ffffffff81237f80>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3176:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d32ef>] __fdget_pos+0x9f/0xc0 fs/file.c:781
2 locks held by getty/3304:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838b0e32>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff820096f4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:22/18301:
 #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: [<ffffffff815795c0>] trylock_super+0x20/0x100 fs/super.c:393

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

NMI backtrace for cpu 0
CPU: 0 PID: 514 Comm: khungtaskd Not tainted 4.9.78-gf518fe4 #22
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d968fd00 ffffffff81d943a9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810bac10 ffff8801d968fd38
 ffffffff81d9f4cd 0000000000000000 0000000000000000 ffff8801ad598418
Call Trace:
 [<ffffffff81d943a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d943a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9f4cd>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9f607>] 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
 [<ffffffff813733c0>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff813733c0>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813733c0>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813733c0>] 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.78-gf518fe4 #22
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801da3d3000 task.stack: ffff8801da3e8000
RIP: 0010:[<ffffffff811cba49>] 
c [<ffffffff811cba49>] constant_test_bit arch/x86/include/asm/bitops.h:311 [inline]
RIP: 0010:[<ffffffff811cba49>] 
c [<ffffffff811cba49>] got_nohz_idle_kick kernel/sched/core.c:623 [inline]
RIP: 0010:[<ffffffff811cba49>] 
c [<ffffffff811cba49>] scheduler_ipi+0x1f9/0x4f0 kernel/sched/core.c:1827
RSP: 0018:ffff8801db307fa8  EFLAGS: 00000046
RAX: 0000000000000003 RBX: 0000000000021b80 RCX: 1ffffffff083fe7d
RDX: 1ffff1003b66437f RSI: ffffffff83c18780 RDI: ffff8801db321bf8
RBP: ffff8801db307fd0 R08: 0000000000000001 R09: ffff88021fffd048
R10: ffff88021fffd058 R11: ffff88021fffd050 R12: ffff8801db321b80
R13: ffff8801db300000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c420103e80 CR3: 00000001ce554000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801da3d3000
c ffffffff841ff840
c 0000000000000001
c ffffffff84a36a78
c
 0000000000000000
c ffff8801db307fe8
c ffffffff838b74e6
c ffffffff84a27968
c
 ffff8801da3efd98
c ffffffff838b5100
c ffff8801da3efce8
c <EOI> 
c 0000000000000000
c
Call Trace:
 <IRQ> 
d [<ffffffff838b74e6>] __smp_reschedule_interrupt arch/x86/kernel/smp.c:259 [inline]
 <IRQ> 
d [<ffffffff838b74e6>] smp_reschedule_interrupt+0x66/0x80 arch/x86/kernel/smp.c:266
 [<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
 [<ffffffff81226580>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81226580>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81226580>] cpu_startup_entry+0x2b0/0x380 kernel/sched/idle.c:303
 [<ffffffff810afcc3>] start_secondary+0x303/0x3e0 arch/x86/kernel/smpboot.c:254
Code: 
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c