flags: 0x8000000000004004(referenced|head)
page dumped because: VM_BUG_ON_PAGE(!PageLocked(page))
------------[ cut here ]------------
kernel BUG at mm/filemap.c:817!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 21739 Comm: syz-executor7 Not tainted 4.4.151-g3a2ec58 #86
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801bc57e000 task.stack: ffff8800b2260000
RIP: 0010:[<ffffffff81421495>]  [<ffffffff81421495>] unlock_page+0x115/0x150 mm/filemap.c:817
RSP: 0018:ffff8800b22677c8  EFLAGS: 00010216
RAX: ffffffff83a6f940 RBX: ffffea00072f8000 RCX: ffffc90000650000
RDX: 000000000001e9a1 RSI: ffffffff81519469 RDI: ffff8801bc57e8dc
RBP: ffff8800b22677e8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: ffffea00072f8300 R14: ffffea00072f8008 R15: ffff8800b22678b0
FS:  00007fb77f596700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2aa6891db8 CR3: 00000001d3e02000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffea00072f8000 dffffc0000000000 ffffea00072f8300 ffffea00072f8008
 ffff8800b22678d8 ffffffff812cf2cd 0000000000000000 ffff8800b2267ab0
 ffff8800baa41400 1ffff1001644cf0a 0000000100000000 ffff8800b2267aa0
Call Trace:
 [<ffffffff812cf2cd>] get_futex_key+0x8ad/0xdc0 kernel/futex.c:598
 [<ffffffff812cfd19>] futex_wait_setup+0xd9/0x330 kernel/futex.c:2376
 [<ffffffff812d021f>] futex_wait+0x2af/0x600 kernel/futex.c:2439
 [<ffffffff812d3b34>] do_futex+0x2a4/0x17f0 kernel/futex.c:3226
 [<ffffffff812d5270>] SYSC_futex kernel/futex.c:3286 [inline]
 [<ffffffff812d5270>] SyS_futex+0x1f0/0x300 kernel/futex.c:3254
 [<ffffffff838cc225>] entry_SYSCALL_64_fastpath+0x22/0x9e
Code: e8 48 8d 04 c0 49 8d 3c c6 e8 b8 bc df ff 5b 41 5c 41 5d 41 5e 5d c3 e8 7a 31 f3 ff 48 c7 c6 e0 bb a9 83 48 89 df e8 bb ee 06 00 <0f> 0b 48 89 df e8 91 d1 0d 00 e9 0a ff ff ff e8 87 d1 0d 00 e9 
RIP  [<ffffffff81421495>] unlock_page+0x115/0x150 mm/filemap.c:817
 RSP <ffff8800b22677c8>
---[ end trace 18472756d07e1b9b ]---