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Buffer I/O error on dev loop0, logical block 6, lost async page write
INFO: task syz-executor2:6480 blocked for more than 120 seconds.
      Not tainted 4.4.124-g851fb4d #60
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D ffff8800b57df990 27976  6480   3805 0x00000004
 ffff8800b57df990 ffff8800b677a108 0000000000000025 ffff8800b6779800
 ffffffff842bdb00 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
 ffff8801db21f4c0 ffffffff84217840 ffff8800b6779800 0000000000000000
Call Trace:
 [<ffffffff8376b59a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
 [<ffffffff837768b0>] schedule_timeout+0x3a0/0x970 kernel/time/timer.c:1515
 [<ffffffff8376942e>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:4941
 [<ffffffff8376c85b>] io_schedule include/linux/sched.h:447 [inline]
 [<ffffffff8376c85b>] bit_wait_io+0x1b/0xc0 kernel/sched/wait.c:595
 [<ffffffff8376bf9c>] __wait_on_bit+0x8c/0x140 kernel/sched/wait.c:395
 [<ffffffff8141db65>] wait_on_page_bit+0x1e5/0x210 mm/filemap.c:758
 [<ffffffff8141dd53>] wait_on_page_writeback include/linux/pagemap.h:530 [inline]
 [<ffffffff8141dd53>] __filemap_fdatawait_range+0x1c3/0x2e0 mm/filemap.c:410
 [<ffffffff814263f3>] filemap_fdatawait_keep_errors+0x63/0x80 mm/filemap.c:468
 [<ffffffff815bd8f0>] fdatawait_one_bdev+0x50/0x70 fs/sync.c:94
 [<ffffffff815d70f9>] iterate_bdevs+0x109/0x260 fs/block_dev.c:1832
 [<ffffffff815be1c1>] sys_sync+0xe1/0x170 fs/sync.c:116
 [<ffffffff837796e5>] entry_SYSCALL_64_fastpath+0x22/0x9e
1 lock held by syz-executor2/6480:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815d70b8>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1830
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.124-g851fb4d #60
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84217840 task.stack: ffffffff84200000
RIP: 0010:[<ffffffff81236ce9>]  [<ffffffff81236ce9>] trace_hardirqs_on_caller+0x139/0x590 kernel/locking/lockdep.c:2601
RSP: 0018:ffffffff84207dd8  EFLAGS: 00000806
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 1ffffffff08fd908
RDX: 1ffffffff0ae04c0 RSI: ffffffff839ff020 RDI: ffffffff842180e8
RBP: ffffffff84207de8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff812917b1
R13: fffffbfff07088c0 R14: ffffffff847ece38 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe1113be58 CR3: 00000001cb396000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801db218570 0000000000000292 ffffffff84207df8 ffffffff8123714d
 ffffffff84207e20 ffffffff812917b1 ffffffff84207e20 dffffc0000000000
 ffffffff847deac8 ffffffff84207ed0 ffffffff81221b30 fffffbfff08fd9d6
Call Trace:
 [<ffffffff8123714d>] trace_hardirqs_on+0xd/0x10 kernel/locking/lockdep.c:2619
 [<ffffffff812917b1>] rcu_idle_exit+0xa1/0x100 kernel/rcu/tree.c:852
 [<ffffffff81221b30>] cpu_idle_poll kernel/sched/idle.c:67 [inline]
 [<ffffffff81221b30>] cpu_idle_loop kernel/sched/idle.c:251 [inline]
 [<ffffffff81221b30>] cpu_startup_entry+0x260/0x8f0 kernel/sched/idle.c:301
 [<ffffffff83766529>] 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: c9 0f 85 c8 00 00 00 9c 58 0f 1f 44 00 00 f6 c4 02 0f 85 5a 03 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 83 e3 07 48 c1 ea 03 <83> c3 03 0f b6 04 02 38 c3 7c 08 84 c0 0f 85 0e 03 00 00 8b 3d 
NMI backtrace for cpu 1
CPU: 1 PID: 486 Comm: khungtaskd Not tainted 4.4.124-g851fb4d #60
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d8d79800 task.stack: ffff8801d8dc0000
RIP: 0010:[<ffffffff810c3fa7>]  [<ffffffff810c3fa7>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3fa7>]  [<ffffffff810c3fa7>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3fa7>]  [<ffffffff810c3fa7>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3fa7>]  [<ffffffff810c3fa7>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8801d8dc7cb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8801d8dc7ce0 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: 00007fea16a5c3c0 CR3: 00000001cb396000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f5a0 ffffffff847f09c0 fffffbfff08fdbec dffffc0000000000
 ffff8801db31bca0 ffff8801d8dc7d00 ffffffff810b9adb ffffffff839f6e40
 0000000000000003 ffff8801d8dc7d60 ffffffff81d115a4 ffffffff8141b803
Call Trace:
 [<ffffffff810b9adb>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d115a4>] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9b74>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff8136944a>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff8136944a>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8136944a>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8136944a>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff811909c8>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff83779b15>] 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 8b 31 17 00 4c 89 e7 57 9d 0f 1f