page:ffffea0007258000 count:2 mapcount:0 mapping:          (null) index:0x0
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: 18183 Comm: syz-executor7 Not tainted 4.4.152-ge15716b #24
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801ca8a6000 task.stack: ffff8800a5fc0000
RIP: 0010:[<ffffffff814213c5>]  [<ffffffff814213c5>] unlock_page+0x115/0x150 mm/filemap.c:817
RSP: 0018:ffff8800a5fc7750  EFLAGS: 00010216
RAX: ffffffff83a6f940 RBX: ffffea0007258000 RCX: ffffc90001458000
RDX: 000000000003bab9 RSI: ffffffff81519559 RDI: ffff8801ca8a68dc
RBP: ffff8800a5fc7770 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: ffffea0007258300 R14: ffffea0007258008 R15: ffff8800a5fc7838
FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000f579db40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000020edfff0 CR3: 00000001cbafa000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffea0007258000 dffffc0000000000 ffffea0007258300 ffffea0007258008
 ffff8800a5fc7860 ffffffff812cf20d 0000000000000000 ffff8800a5fc7a38
 ffff8801d70f3200 1ffff10014bf8efb 0000000100000000 ffff8800a5fc7a28
Call Trace:
 [<ffffffff812cf20d>] get_futex_key+0x8ad/0xdc0 kernel/futex.c:598
 [<ffffffff812cfc59>] futex_wait_setup+0xd9/0x330 kernel/futex.c:2376
 [<ffffffff812d015f>] futex_wait+0x2af/0x600 kernel/futex.c:2439
 [<ffffffff812d3a74>] do_futex+0x2a4/0x17f0 kernel/futex.c:3226
 [<ffffffff812d5ac9>] C_SYSC_futex kernel/futex_compat.c:200 [inline]
 [<ffffffff812d5ac9>] compat_SyS_futex+0x1d9/0x2f0 kernel/futex_compat.c:174
 [<ffffffff81006d94>] do_syscall_32_irqs_on arch/x86/entry/common.c:393 [inline]
 [<ffffffff81006d94>] do_fast_syscall_32+0x324/0x8b0 arch/x86/entry/common.c:460
 [<ffffffff838cdec3>] sysenter_flags_fixed+0xd/0x1a
Code: e8 48 8d 04 c0 49 8d 3c c6 e8 88 bd df ff 5b 41 5c 41 5d 41 5e 5d c3 e8 8a 31 f3 ff 48 c7 c6 e0 bb a9 83 48 89 df e8 bb ee 06 00 <0f> 0b 48 89 df e8 51 d3 0d 00 e9 0a ff ff ff e8 47 d3 0d 00 e9 
RIP  [<ffffffff814213c5>] unlock_page+0x115/0x150 mm/filemap.c:817
 RSP <ffff8800a5fc7750>
---[ end trace 868dcb2897baf176 ]---