Buffer I/O error on dev loop0, logical block 10, lost async page write
INFO: task syz-executor1:14218 blocked for more than 120 seconds.
      Not tainted 4.4.120-gd63fdf6 #28
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor1   D ffff8800b8c77d18 28112 14218   3849 0x00000004
 ffff8800b8c77d18 ffff8801d7bf8000 0000000000000000 0000000000000007
 ffff8801d7bf8000 dffffc0000000000 ffff8801db31fdb8 ffff8801db31fde0
 ffff8801db31f4d8 ffff8801d9b49800 ffff8801d7bf8000 0000000000000000
Call Trace:
 [<ffffffff8376582a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3353
 [<ffffffff83766023>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3386
 [<ffffffff8376a5e6>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff8376a5e6>] mutex_lock_nested+0x306/0x850 kernel/locking/mutex.c:621
 [<ffffffff815d6838>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1830
 [<ffffffff815bd941>] sys_sync+0xe1/0x170 fs/sync.c:116
 [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
1 lock held by syz-executor1/14218:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815d6838>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1830
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 486 Comm: khungtaskd Not tainted 4.4.120-gd63fdf6 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bb308000 task.stack: ffff8800bb3e8000
RIP: 0010:[<ffffffff810c3e67>]  [<ffffffff810c3e67>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3e67>]  [<ffffffff810c3e67>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3e67>]  [<ffffffff810c3e67>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3e67>]  [<ffffffff810c3e67>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bb3efcb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bb3efce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426f420 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c420049e80 CR3: 00000001d393e000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f420 ffffffff847efb00 fffffbfff08fda14 dffffc0000000000
 ffff8801db31bca0 ffff8800bb3efd00 ffffffff810b999b ffffffff839f63c0
 0000000000000003 ffff8800bb3efd60 ffffffff81d0eff4 ffffffff8141b053
Call Trace:
 [<ffffffff810b999b>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d0eff4>] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9a34>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff81368c9a>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff81368c9a>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81368c9a>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81368c9a>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff81190788>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff83773d85>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:506
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 6b 2f 17 00 4c 89 e7 57 9d 0f 1f 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.120-gd63fdf6 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9b49800 task.stack: ffff8801d9b58000
RIP: 0010:[<ffffffff81d161bd>]  [<ffffffff81d161bd>] __write_once_size include/linux/compiler.h:247 [inline]
RIP: 0010:[<ffffffff81d161bd>]  [<ffffffff81d161bd>] __rb_change_child include/linux/rbtree_augmented.h:130 [inline]
RIP: 0010:[<ffffffff81d161bd>]  [<ffffffff81d161bd>] __rb_erase_augmented include/linux/rbtree_augmented.h:155 [inline]
RIP: 0010:[<ffffffff81d161bd>]  [<ffffffff81d161bd>] rb_erase+0x3dd/0x1b60 lib/rbtree.c:427
RSP: 0018:ffff8801d9b5fba8  EFLAGS: 00000046
RAX: dffffc0000000000 RBX: ffff8801c7a96060 RCX: 1ffff1003b663eb3
RDX: 1ffff1003b663eb2 RSI: ffff8801db31f590 RDI: ffff8801c7a96080
RBP: ffff8801d9b5fbf0 R08: ffff8801c7a960e0 R09: ffff8801db31f4c0
R10: dffffc0000000000 R11: 1ffff1003b36bf72 R12: 0000000000000001
R13: ffff8801c7a96070 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5bfc44a000 CR3: 00000001d393e000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801db31f630 ffff8801c7a960c8 ffff8801c7a960e0 ffff8801c7a960c8
 ffff8801c7a96060 ffff8801db31f568 ffff8801c7a96070 ffff8801db31f598
 ffff8801db31f4c0 ffff8801d9b5fc28 ffffffff811e4930 dffffc0000000000
Call Trace:
 [<ffffffff811e4930>] __dequeue_entity kernel/sched/fair.c:589 [inline]
 [<ffffffff811e4930>] set_next_entity+0x2b0/0x3d0 kernel/sched/fair.c:3687
 [<ffffffff81200631>] pick_next_task_fair+0xb11/0x2220 kernel/sched/fair.c:7108
 [<ffffffff837645d4>] pick_next_task kernel/sched/core.c:3189 [inline]
 [<ffffffff837645d4>] __schedule+0xc44/0x1ca0 kernel/sched/core.c:3306
 [<ffffffff8376582a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3353
 [<ffffffff83766023>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3386
 [<ffffffff81221830>] cpu_idle_loop kernel/sched/idle.c:279 [inline]
 [<ffffffff81221830>] cpu_startup_entry+0x2c0/0x8f0 kernel/sched/idle.c:301
 [<ffffffff810adc64>] start_secondary+0x304/0x3e0 arch/x86/kernel/smpboot.c:242
Code: d2 16 00 00 49 89 18 48 83 c4 20 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 b8 00 00 00 00 00 fc ff df 48 89 f2 48 c1 ea 03 80 3c 02 00 <0f> 85 ed 0e 00 00 4d 85 f6 4c 89 36 74 ce 48 b8 00 00 00 00 00