Buffer I/O error on dev loop0, logical block 24, async page read
INFO: task syz-executor2:21600 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-executor2   D ffff8800b5b97530 26480 21600   3683 0x20020006
 ffff8800b5b97530 ffff8800b2e28908 0000000000000025 ffff8800b2e28000
 ffffffff842bdb00 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
 ffff8801db21f4c0 ffffffff84217840 ffff8800b2e28000 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-executor2/21600:
 #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: 0 Comm: swapper/0 Not tainted 4.4.125-g38f41ec #21
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84217840 task.stack: ffffffff84200000
RIP: 0010:[<ffffffff811c2aa5>]  [<ffffffff811c2aa5>] constant_test_bit arch/x86/include/asm/bitops.h:311 [inline]
RIP: 0010:[<ffffffff811c2aa5>]  [<ffffffff811c2aa5>] got_nohz_idle_kick kernel/sched/core.c:717 [inline]
RIP: 0010:[<ffffffff811c2aa5>]  [<ffffffff811c2aa5>] scheduler_ipi+0x205/0x520 kernel/sched/core.c:1849
RSP: 0018:ffff8801db207f68  EFLAGS: 00000046
RAX: dffffc0000000000 RBX: 000000000001f4c0 RCX: 1ffffffff08fd938
RDX: 1ffff1003b643ea8 RSI: ffffffff839fef20 RDI: ffff8801db21f540
RBP: ffff8801db207f90 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801db21f4c0
R13: ffff8801db200000 R14: ffffffff847ecfb8 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5ae58ac000 CR3: 00000000b6ea8000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000000 ffffffff8426f5a0 0000000000000000 fffffbfff07088c0
 ffffffff847ecfb8 ffff8801db207fa8 ffffffff810ab4d1 ffffffff847dec48
 ffffffff84207dc0 ffffffff8377be70 ffffffff84207d18 <EOI>  0000000000000000
Call Trace:
 <IRQ> 
d [<ffffffff810ab4d1>] __smp_reschedule_interrupt arch/x86/kernel/smp.c:257 [inline]
 <IRQ> 
d [<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
 [<ffffffff837667b9>] rest_init+0x189/0x190 init/main.c:410
 [<ffffffff84823811>] start_kernel+0x6b9/0x6ee init/main.c:682
 [<ffffffff84822312>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84822454>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:185
Code: 03 00 00 4c 8b 2c c5 c0 c9 7e 84 48 b8 00 00 00 00 00 fc ff df 4d 01 ec 49 8d bc 24 80 00 00 00 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 f9 02 00 00 49 8b 84 24 80 00 00 00 a8 02 74 8c 48 b8 00 
NMI backtrace for cpu 1
CPU: 1 PID: 486 Comm: khungtaskd Not tainted 4.4.125-g38f41ec #21
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bb36b000 task.stack: ffff8800bb308000
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:ffff8800bb30fcb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bb30fce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426f5a0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f73eb190000 CR3: 00000000b6ea8000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f5a0 ffffffff847f0b40 fffffbfff08fdc1c dffffc0000000000
 ffff8801db31bca0 ffff8800bb30fd00 ffffffff810b9abb ffffffff839f6dc0
 0000000000000003 ffff8800bb30fd60 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