syzbot

INFO: task syz-executor292:3793 blocked for more than 140 seconds.
      Not tainted 4.4.139-g7ba5557 #66
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor292 D ffff8800b1fd74e0 26064  3793   3791 0x00000000
 ffff8800b1fd74e0 000000000000003f 00007ffca4ff4788 b477450dc68f78cb
 ffff8800b1fd7600 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
 ffff8801db21f4c0 ffffffff84417840 ffff8801d88bc800 0000000000000000
Call Trace:
 [<ffffffff838b381a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
 [<ffffffff838bec31>] schedule_timeout+0x481/0x8b0 kernel/time/timer.c:1515
 [<ffffffff838b16da>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:4941
 [<ffffffff838b4a6b>] io_schedule include/linux/sched.h:447 [inline]
 [<ffffffff838b4a6b>] bit_wait_io+0x1b/0xd0 kernel/sched/wait.c:595
 [<ffffffff838b45d2>] __wait_on_bit_lock.part.4+0x92/0x140 kernel/sched/wait.c:434
 [<ffffffff838b4689>] __wait_on_bit_lock+0x9/0x10 kernel/sched/wait.c:427
 [<ffffffff8141cdfd>] __lock_page+0x17d/0x1f0 mm/filemap.c:888
 [<ffffffff815b9b0b>] lock_page include/linux/pagemap.h:458 [inline]
 [<ffffffff815b9b0b>] __generic_file_splice_read+0x7eb/0xbb0 fs/splice.c:412
 [<ffffffff815b9fb2>] generic_file_splice_read+0xe2/0x1c0 fs/splice.c:542
 [<ffffffff815b6107>] do_splice_to+0xf7/0x140 fs/splice.c:1154
 [<ffffffff815b6392>] splice_direct_to_actor+0x242/0x830 fs/splice.c:1226
 [<ffffffff815b6b23>] do_splice_direct+0x1a3/0x270 fs/splice.c:1337
 [<ffffffff815206c4>] do_sendfile+0x4e4/0xb80 fs/read_write.c:1227
 [<ffffffff815226b3>] SYSC_sendfile64 fs/read_write.c:1282 [inline]
 [<ffffffff815226b3>] SyS_sendfile64+0xc3/0x150 fs/read_write.c:1274
 [<ffffffff838c1865>] entry_SYSCALL_64_fastpath+0x22/0x9e
1 lock held by syz-executor292/3793:
 #0:  (sb_writers#5){.+.+.+}, at: [<ffffffff81520a43>] file_start_write include/linux/fs.h:2541 [inline]
 #0:  (sb_writers#5){.+.+.+}, at: [<ffffffff81520a43>] do_sendfile+0x863/0xb80 fs/read_write.c:1226
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 492 Comm: khungtaskd Not tainted 4.4.139-g7ba5557 #66
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d8e11800 task.stack: ffff8801d8e00000
RIP: 0010:[<ffffffff810bfb46>]  [<ffffffff810bfb46>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810bfb46>]  [<ffffffff810bfb46>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810bfb46>]  [<ffffffff810bfb46>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810bfb46>]  [<ffffffff810bfb46>] flat_send_IPI_mask+0xf6/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8801d8e07cc8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8801d8e07cf0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: 0000000000000002 R15: ffffffff8446f6a0
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f80d1bc5000 CR3: 00000000b380c000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8446f6a0 ffffffff84a18ca0 0000000000000007 fffffbfff0942c44
 0000000000000040 ffff8801d8e07d10 ffffffff810b5b01 ffffffff83c0b2a0
 0000000000000003 ffff8801d8e07d68 ffffffff81e18603 ffffffff8140dd6f
Call Trace:
 [<ffffffff810b5b01>] nmi_raise_cpu_backtrace+0x61/0x80 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81e18603>] nmi_trigger_all_cpu_backtrace.cold.4+0x70/0xad lib/nmi_backtrace.c:85
 [<ffffffff810b5ba4>] 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
 [<ffffffff838c1c95>] 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 e2 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.139-g7ba5557 #66
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9a41800 task.stack: ffff8801d9a50000
RIP: 0010:[<ffffffff810cc306>]  [<ffffffff810cc306>] native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:49
RSP: 0018:ffff8801d9a57da0  EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffffffff84a05d68 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801d9a420dc
RBP: ffff8801d9a57da0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: fffffbfff07488e8 R15: ffffffff84a05d68
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f80d1bc5000 CR3: 00000000b380c000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d9a57dd8 ffffffff81025cf5 ffff8801d9a58000 0000000000000000
 0000000000000000 fffffbfff07488e8 ffffffff84a05d68 ffff8801d9a57de8
 ffffffff81027240 ffff8801d9a57e00 ffffffff8121bc07 dffffc0000000000
Call Trace:
 [<ffffffff81025cf5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81025cf5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:290
 [<ffffffff81027240>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:281
 [<ffffffff8121bc07>] default_idle_call+0x57/0x70 kernel/sched/idle.c:93
 [<ffffffff8121c3af>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff8121c3af>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff8121c3af>] cpu_startup_entry+0x6af/0x780 kernel/sched/idle.c:301
 [<ffffffff810a9e74>] start_secondary+0x324/0x400 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