Buffer I/O error on dev loop0, logical block 24, async page read
INFO: task syz-executor4:17884 blocked for more than 120 seconds.
      Not tainted 4.4.125-g38f41ec #21
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D ffff8800b626f530 27096 17884   3632 0x20020006
 ffff8800b626f530 ffff8800b5798908 0000000000000025 ffff8800b5798000
 ffffffff842bdb00 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
 ffff8801db21f4c0 ffffffff84217840 ffff8800b5798000 0000000000000000
Call Trace:
 [<ffffffff8376b82a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
 [<ffffffff83776b40>] schedule_timeout+0x3a0/0x970 kernel/time/timer.c:1515
 [<ffffffff837696be>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:4941
 [<ffffffff8376caeb>] io_schedule include/linux/sched.h:447 [inline]
 [<ffffffff8376caeb>] bit_wait_io+0x1b/0xc0 kernel/sched/wait.c:595
 [<ffffffff8376c22c>] __wait_on_bit+0x8c/0x140 kernel/sched/wait.c:395
 [<ffffffff8141dcf5>] wait_on_page_bit+0x1e5/0x210 mm/filemap.c:758
 [<ffffffff8141dee3>] wait_on_page_writeback include/linux/pagemap.h:530 [inline]
 [<ffffffff8141dee3>] __filemap_fdatawait_range+0x1c3/0x2e0 mm/filemap.c:410
 [<ffffffff8141e025>] filemap_fdatawait_range+0x25/0x50 mm/filemap.c:440
 [<ffffffff814240e5>] filemap_fdatawait mm/filemap.c:490 [inline]
 [<ffffffff814240e5>] filemap_write_and_wait+0xf5/0x120 mm/filemap.c:507
 [<ffffffff815d35c0>] __sync_blockdev fs/block_dev.c:178 [inline]
 [<ffffffff815d35c0>] sync_blockdev.part.21+0x50/0x70 fs/block_dev.c:187
 [<ffffffff815d3bd4>] sync_blockdev fs/block_dev.c:174 [inline]
 [<ffffffff815d3bd4>] __blkdev_put+0x184/0x7e0 fs/block_dev.c:1522
 [<ffffffff815d50a5>] blkdev_put+0x85/0x550 fs/block_dev.c:1600
 [<ffffffff815d55fb>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1607
 [<ffffffff81523f43>] __fput+0x233/0x6d0 fs/file_table.c:208
 [<ffffffff81524465>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bd44>] task_work_run+0x104/0x180 kernel/task_work.c:115
 [<ffffffff8115d824>] get_signal+0x11f4/0x1550 kernel/signal.c:2147
 [<ffffffff8100e7fb>] do_signal+0x8b/0x1d40 arch/x86/kernel/signal.c:712
 [<ffffffff810035fa>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:248
 [<ffffffff81007084>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81007084>] syscall_return_slowpath arch/x86/entry/common.c:348 [inline]
 [<ffffffff81007084>] do_syscall_32_irqs_on arch/x86/entry/common.c:398 [inline]
 [<ffffffff81007084>] do_fast_syscall_32+0x614/0x8a0 arch/x86/entry/common.c:459
 [<ffffffff8377b2aa>] sysenter_flags_fixed+0xd/0x17
1 lock held by syz-executor4/17884:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815d3b0c>] __blkdev_put+0xbc/0x7e0 fs/block_dev.c:1516
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 487 Comm: khungtaskd Not tainted 4.4.125-g38f41ec #21
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800badc1800 task.stack: ffff8800bad20000
RIP: 0010:[<ffffffff810c3f87>]  [<ffffffff810c3f87>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3f87>]  [<ffffffff810c3f87>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3f87>]  [<ffffffff810c3f87>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3f87>]  [<ffffffff810c3f87>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bad27cb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bad27ce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426f5a0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f85ab6b8000 CR3: 00000001d3b68000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f5a0 ffffffff847f0b40 fffffbfff08fdc1c dffffc0000000000
 ffff8801db31bca0 ffff8800bad27d00 ffffffff810b9abb ffffffff839f6dc0
 0000000000000003 ffff8800bad27d60 ffffffff81d11764 ffffffff8141b993
Call Trace:
 [<ffffffff810b9abb>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d11764>] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9b54>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff813695ca>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff813695ca>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813695ca>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813695ca>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff81190b48>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff83779d95>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510
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 2b 33 17 00 4c 89 e7 57 9d 0f 1f 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.125-g38f41ec #21
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9b49800 task.stack: ffff8801d9b58000
RIP: 0010:[<ffffffff813616cc>]  [<ffffffff813616cc>] __sanitizer_cov_trace_pc+0x4c/0x50 kernel/kcov.c:110
RSP: 0018:ffff8801db307f50  EFLAGS: 00000093
RAX: ffff8801d9b49800 RBX: 000000000001f4c0 RCX: ffffffff81d66789
RDX: 0000000000000000 RSI: ffffffff839fef20 RDI: ffff8801db320020
RBP: ffff8801db307f58 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801db31f4c0
R13: fffffbfff07088c0 R14: ffffffff847ecfb8 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000002313000 CR3: 00000001d3b68000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff81d66789 ffff8801db307f90 ffffffff811c2a55 0000000000000000
 ffffffff8426f5a0 0000000000000001 fffffbfff07088c0 ffffffff847ecfb8
 ffff8801db307fa8 ffffffff810ab4d1 ffffffff847dec48 ffff8801d9b5fd98
Call Trace:
 [<ffffffff811c2a55>] got_nohz_idle_kick kernel/sched/core.c:715 [inline]
 [<ffffffff811c2a55>] scheduler_ipi+0x1b5/0x520 kernel/sched/core.c:1849
 [<ffffffff810ab4d1>] __smp_reschedule_interrupt arch/x86/kernel/smp.c:257 [inline]
 [<ffffffff810ab4d1>] smp_reschedule_interrupt+0x61/0x80 arch/x86/kernel/smp.c:263
 [<ffffffff8377be70>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:764
 <EOI> 
d [<ffffffff810d0666>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:49
 [<ffffffff81027e65>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81027e65>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:290
 [<ffffffff810293da>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:281
 [<ffffffff81221948>] default_idle_call+0x48/0x70 kernel/sched/idle.c:93
 [<ffffffff8122204d>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff8122204d>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff8122204d>] cpu_startup_entry+0x5fd/0x8f0 kernel/sched/idle.c:301
 [<ffffffff810adcd4>] start_secondary+0x304/0x3e0 arch/x86/kernel/smpboot.c:242
Code: 90 98 12 00 00 83 fa 02 75 20 48 8b b0 a0 12 00 00 8b 80 9c 12 00 00 48 8b 16 48 83 c2 01 48 39 d0 76 07 48 89 0c d6 48 89 16 5d <c3> 0f 1f 00 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 89 f3 48