blk_update_request: I/O error, dev loop0, sector 1256
Buffer I/O error on dev loop0, logical block 157, lost async page write
INFO: task syz-executor4:25582 blocked for more than 120 seconds.
      Not tainted 4.4.136-gfb7e319 #59
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D ffff88009cfdf4e0 26488 25582   3934 0x00000004
 ffff88009cfdf4e0 000000000000003f 0000000000000001 4d51296277d7a004
 ffff88009cfdf600 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
 ffff8801db21f4c0 ffff8801d7286000 ffff8800b6379800 0000000000000000
Call Trace:
 [<ffffffff838b47fa>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
 [<ffffffff838bfc11>] schedule_timeout+0x481/0x8b0 kernel/time/timer.c:1515
 [<ffffffff838b26ba>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:4941
 [<ffffffff838b5a4b>] io_schedule include/linux/sched.h:447 [inline]
 [<ffffffff838b5a4b>] bit_wait_io+0x1b/0xd0 kernel/sched/wait.c:595
 [<ffffffff838b55b2>] __wait_on_bit_lock.part.4+0x92/0x140 kernel/sched/wait.c:434
 [<ffffffff838b5669>] __wait_on_bit_lock+0x9/0x10 kernel/sched/wait.c:427
 [<ffffffff8141cdfd>] __lock_page+0x17d/0x1f0 mm/filemap.c:888
 [<ffffffff815b9aab>] lock_page include/linux/pagemap.h:458 [inline]
 [<ffffffff815b9aab>] __generic_file_splice_read+0x7eb/0xbb0 fs/splice.c:412
 [<ffffffff815b9f52>] generic_file_splice_read+0xe2/0x1c0 fs/splice.c:542
 [<ffffffff815b60a7>] do_splice_to+0xf7/0x140 fs/splice.c:1154
 [<ffffffff815b6332>] splice_direct_to_actor+0x242/0x830 fs/splice.c:1226
 [<ffffffff815b6ac3>] do_splice_direct+0x1a3/0x270 fs/splice.c:1337
 [<ffffffff81520664>] do_sendfile+0x4e4/0xb80 fs/read_write.c:1227
 [<ffffffff81522653>] SYSC_sendfile64 fs/read_write.c:1282 [inline]
 [<ffffffff81522653>] SyS_sendfile64+0xc3/0x150 fs/read_write.c:1274
 [<ffffffff838c2825>] entry_SYSCALL_64_fastpath+0x22/0x9e
no locks held by syz-executor4/25582.
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 493 Comm: khungtaskd Not tainted 4.4.136-gfb7e319 #59
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bacf6000 task.stack: ffff8800baca0000
RIP: 0010:[<ffffffff810bfeb6>]  [<ffffffff810bfeb6>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810bfeb6>]  [<ffffffff810bfeb6>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810bfeb6>]  [<ffffffff810bfeb6>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810bfeb6>]  [<ffffffff810bfeb6>] flat_send_IPI_mask+0xf6/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800baca7cc8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800baca7cf0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: 0000000000000002 R15: ffffffff8446f7a0
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f20200fd000 CR3: 00000000af71b000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8446f7a0 ffffffff84a18ea0 0000000000000007 fffffbfff0942c84
 0000000000000040 ffff8800baca7d10 ffffffff810b5e71 ffffffff83c0b560
 0000000000000003 ffff8800baca7d68 ffffffff81e19e23 ffff8800b6379800
Call Trace:
 [<ffffffff810b5e71>] nmi_raise_cpu_backtrace+0x61/0x80 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81e19e23>] nmi_trigger_all_cpu_backtrace.cold.4+0x70/0xad lib/nmi_backtrace.c:85
 [<ffffffff810b5f14>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff8141a459>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff8141a459>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8141a459>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8141a459>] watchdog.cold.1+0xd3/0xee kernel/hung_task.c:238
 [<ffffffff81190958>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff838c2c55>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510
Code: b3 5f ff f6 c4 10 75 e2 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 f2 09 da 80 cf 04 41 83 fe 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 75 1a 4c 89 e7 57 9d 0f 1f 44 00 00 e8 72 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.136-gfb7e319 #59
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9a41800 task.stack: ffff8801d9a50000
RIP: 0010:[<ffffffff812c50d0>]  [<ffffffff812c50d0>] tick_nohz_stop_idle+0x0/0x70 kernel/time/tick-sched.c:545
RSP: 0018:ffff8801d9a57dd0  EFLAGS: 00000093
RAX: ffff8801d9a41800 RBX: ffff8801db319c40 RCX: 0000000000000017
RDX: 0000000000000000 RSI: 000000a7f07318dc RDI: ffff8801db319c40
RBP: ffff8801d9a57e00 R08: ffff88021fffd058 R09: 0000000000000008
R10: ffffed0043fffa09 R11: 0000000000000001 R12: ffff8801db319cb4
R13: ffff8801db319cd0 R14: 000000a7f07318dc R15: ffffffff84a05f68
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f201ece0140 CR3: 00000000af71b000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff812c738f ffff8801d9a57df0 dffffc0000000000 ffff8801d9a58000
 0000000000000000 fffffbfff074890c ffff8801d9a57ea8 ffffffff8121bfa7
 fffffbfff0942a6e ffff8801d9a57e38 0000000041b58ab3 ffffffff841d90a4
Call Trace:
 [<ffffffff8121bfa7>] cpu_idle_loop kernel/sched/idle.c:267 [inline]
 [<ffffffff8121bfa7>] cpu_startup_entry+0x2a7/0x780 kernel/sched/idle.c:301
 [<ffffffff810aa1e4>] start_secondary+0x324/0x400 arch/x86/kernel/smpboot.c:242
Code: e9 4b ff ff ff e8 01 47 23 00 e9 89 fe ff ff e8 f7 46 23 00 e9 cd fe ff ff e8 ed 46 23 00 eb cb e8 e6 46 23 00 eb 9d 0f 1f 40 00 <55> 48 89 e5 41 54 49 89 f4 53 48 89 fb e8 ce c3 08 00 e8 89 99