page:ffffea0002dc0000 count:2 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000004004(referenced|head)
page dumped because: VM_BUG_ON_PAGE(!PageLocked(page))
------------[ cut here ]------------
kernel BUG at mm/filemap.c:819!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 3830 Comm: syz-executor451 Not tainted 4.4.130-g12ef385 #27
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800ad8b1800 task.stack: ffff8800bb310000
RIP: 0010:[<ffffffff8141df55>]  [<ffffffff8141df55>] unlock_page+0x115/0x150 mm/filemap.c:819
RSP: 0018:ffff8800bb317760  EFLAGS: 00010293
RAX: ffffffff83a6e7c0 RBX: ffffea0002dc0000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81513389 RDI: ffff8800ad8b20dc
RBP: ffff8800bb317780 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: ffff8800bb317a30 R14: ffffea0002dc1480 R15: ffffea0002dc0008
FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000f77ccb40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000204a4ff0 CR3: 00000000b34ab000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffea0002dc0000 dffffc0000000000 ffff8800bb317a30 ffffea0002dc1480
 ffff8800bb317868 ffffffff812cc1bc 0000000000000001 ffff8800bb317818
 0000000000000046 ffff8801d9b5a800 00000000ad8b20d8 ffff8800bb317a40
Call Trace:
 [<ffffffff812cc1bc>] get_futex_key+0xadc/0xd80 kernel/futex.c:598
 [<ffffffff812cc999>] futex_wait_setup+0xd9/0x330 kernel/futex.c:2336
 [<ffffffff812cce9f>] futex_wait+0x2af/0x600 kernel/futex.c:2399
 [<ffffffff812d07b2>] do_futex+0x2a2/0x1770 kernel/futex.c:3186
 [<ffffffff812d2789>] C_SYSC_futex kernel/futex_compat.c:200 [inline]
 [<ffffffff812d2789>] compat_SyS_futex+0x1d9/0x2f0 kernel/futex_compat.c:174
 [<ffffffff81006d96>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d96>] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:459
 [<ffffffff838c0e6a>] sysenter_flags_fixed+0xd/0x17
Code: e8 48 8d 04 c0 49 8d 3c c6 e8 08 bf df ff 5b 41 5c 41 5d 41 5e 5d c3 e8 9a 32 f3 ff 48 c7 c6 60 aa a9 83 48 89 df e8 4b eb 06 00 <0f> 0b 48 89 df e8 f1 b1 0d 00 e9 0a ff ff ff e8 e7 b1 0d 00 e9 
RIP  [<ffffffff8141df55>] unlock_page+0x115/0x150 mm/filemap.c:819
 RSP <ffff8800bb317760>
---[ end trace f7f1500ebaf6b2f9 ]---