Buffer I/O error on dev loop0, logical block 16, async page read
INFO: task syz-executor2:18734 blocked for more than 120 seconds.
      Not tainted 4.4.114-ga81d322 #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D ffff8800b571f550 28808 18734   3954 0x00000004
 ffff8800b571f550 ffff8800b571f540 ffffffff81dac9b3 ffffffff812eb3a3
 ffff8800b5a28000 00007fc812134c00 ffff8801db31fdb8 ffff8801db31fde0
 ffff8801db31f4d8 ffff8801d0cb3000 ffff8800b5a28000 ffff8800b571fb40
Call Trace:
 [<ffffffff83765dba>] schedule+0x7a/0x1b0 kernel/sched/core.c:3353
 [<ffffffff837710d0>] schedule_timeout+0x3a0/0x970 kernel/time/timer.c:1515
 [<ffffffff83763d4e>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:4935
 [<ffffffff8376707b>] io_schedule include/linux/sched.h:447 [inline]
 [<ffffffff8376707b>] bit_wait_io+0x1b/0xc0 kernel/sched/wait.c:595
 [<ffffffff83766bbf>] __wait_on_bit_lock+0x8f/0x140 kernel/sched/wait.c:434
 [<ffffffff8141df3d>] __lock_page+0x18d/0x1f0 mm/filemap.c:888
 [<ffffffff814214e6>] lock_page include/linux/pagemap.h:458 [inline]
 [<ffffffff814214e6>] pagecache_get_page+0x316/0x3f0 mm/filemap.c:1161
 [<ffffffff814219a3>] grab_cache_page_write_begin+0x63/0x90 mm/filemap.c:2494
 [<ffffffff815cb38a>] block_write_begin+0x3a/0xd0 fs/buffer.c:2038
 [<ffffffff815d096c>] blkdev_write_begin+0x3c/0x50 fs/block_dev.c:316
 [<ffffffff8141eeaa>] generic_perform_write+0x28a/0x530 mm/filemap.c:2550
 [<ffffffff8142542a>] __generic_file_write_iter+0x35a/0x580 mm/filemap.c:2675
 [<ffffffff815d13e4>] blkdev_write_iter+0x1d4/0x490 fs/block_dev.c:1655
 [<ffffffff8151df98>] do_iter_readv_writev+0x138/0x1e0 fs/read_write.c:664
 [<ffffffff8151f732>] do_readv_writev+0x2d2/0x6e0 fs/read_write.c:808
 [<ffffffff8151fc6b>] vfs_writev+0x7b/0xb0 fs/read_write.c:847
 [<ffffffff81522659>] SYSC_pwritev fs/read_write.c:936 [inline]
 [<ffffffff81522659>] SyS_pwritev+0x199/0x230 fs/read_write.c:922
 [<ffffffff83773edf>] entry_SYSCALL_64_fastpath+0x1c/0x98
no locks held by syz-executor2/18734.
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 485 Comm: khungtaskd Not tainted 4.4.114-ga81d322 #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bace9800 task.stack: ffff8800bacf0000
RIP: 0010:[<ffffffff810c3d57>]  [<ffffffff810c3d57>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3d57>]  [<ffffffff810c3d57>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3d57>]  [<ffffffff810c3d57>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3d57>]  [<ffffffff810c3d57>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bacf7cb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bacf7ce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426f3a0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6e168f3000 CR3: 00000001cde38000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f3a0 ffffffff847ef700 fffffbfff08fd994 dffffc0000000000
 ffff8801db31bca0 ffff8800bacf7d00 ffffffff810b988b ffffffff839f6180
 0000000000000003 ffff8800bacf7d60 ffffffff81d0e8b4 0000000000000000
Call Trace:
 [<ffffffff810b988b>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d0e8b4>] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9924>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff81368cba>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff81368cba>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81368cba>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81368cba>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff811907d8>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff83774305>] 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 30 17 00 4c 89 e7 57 9d 0f 1f 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.114-ga81d322 #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9b49800 task.stack: ffff8801d9b58000
RIP: 0010:[<ffffffff810d0536>]  [<ffffffff810d0536>] native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:49
RSP: 0018:ffff8801d9b5fd98  EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffffffff847dd808 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801d9b4a0cc
RBP: ffff8801d9b5fd98 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: fffffbfff070887c R14: ffffffff847ebb78 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6e154d6140 CR3: 00000001cde38000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d9b5fdd0 ffffffff81027ed5 ffff8801d9b60000 ffffffff847dd808
 fffffbfff070887c ffffffff847ebb78 0000000000000000 ffff8801d9b5fde0
 ffffffff8102945a ffff8801d9b5fdf8 ffffffff81221458 dffffc0000000000
Call Trace:
 [<ffffffff81027ed5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81027ed5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:291
 [<ffffffff8102945a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:282
 [<ffffffff81221458>] default_idle_call+0x48/0x70 kernel/sched/idle.c:93
 [<ffffffff81221b5d>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff81221b5d>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff81221b5d>] cpu_startup_entry+0x5fd/0x8f0 kernel/sched/idle.c:301
 [<ffffffff810adb54>] start_secondary+0x304/0x3e0 arch/x86/kernel/smpboot.c:242
Code: 00 00 00 00 00 55 48 89 e5 fa 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb f4 <5d> c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 f4 5d c3 66 0f 1f 84