RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000216 R12: 00000000004b9b22
R13: 0000000000000006 R14: 00007f8545a3cc30 R15: ffffffffffffffff
list_del corruption. prev->next should be ffff8801d56bf138, but was ffff8801cea7c000
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:53!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 15428 Comm: syz-executor0 Not tainted 4.13.0-rc6+ #54
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d56b0180 task.stack: ffff8801d56b8000
RIP: 0010:__list_del_entry_valid+0xef/0x150 lib/list_debug.c:51
RSP: 0018:ffff8801d56beef8 EFLAGS: 00010282
RAX: 0000000000000054 RBX: ffff8801d5af7a80 RCX: 0000000000000000
RDX: 0000000000000054 RSI: ffffffff8159319e RDI: ffffed003aad7dd3
RBP: ffff8801d56bef10 R08: 0000000000000001 R09: 0000000000000000
R10: ffff8801d56bedd8 R11: 0000000000000000 R12: ffff8801d5af7a80
R13: dffffc0000000000 R14: ffff8801c4c00380 R15: ffff8801d56bf140
FS:  00007f8545a5e700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020013000 CR3: 00000001d86d8000 CR4: 00000000001426f0
Call Trace:
 __list_del_entry include/linux/list.h:116 [inline]
 list_del include/linux/list.h:124 [inline]
 __remove_wait_queue include/linux/wait.h:182 [inline]
 userfaultfd_event_wait_completion+0x519/0x910 fs/userfaultfd.c:569
 dup_fctx fs/userfaultfd.c:665 [inline]
 dup_userfaultfd_complete+0x2de/0x480 fs/userfaultfd.c:673
 dup_mmap kernel/fork.c:716 [inline]
 dup_mm kernel/fork.c:1176 [inline]
 copy_mm+0xde2/0x1247 kernel/fork.c:1230
 copy_process.part.34+0x1ec4/0x4bd0 kernel/fork.c:1736
 copy_process kernel/fork.c:1546 [inline]
 _do_fork+0x1ef/0xfb0 kernel/fork.c:2027
 SYSC_clone kernel/fork.c:2137 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2131
 do_syscall_64+0x26c/0x800 arch/x86/entry/common.c:284
 entry_SYSCALL64_slow_path+0x25/0x25
RIP: 0033:0x4512e9
RSP: 002b:00007f8545a5dc08 EFLAGS: 00000216 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00000000007180a8 RCX: 00000000004512e9
RDX: 000000002003b000 RSI: 0000000020038f62 RDI: 0000000000000000
RBP: 00000000000003b0 R08: 0000000020056000 R09: 0000000000000000
R10: 0000000020010000 R11: 0000000000000216 R12: 00000000004b65e0
R13: 00000000ffffffff R14: 0000000000000000 R15: 0000000020038f62
Code: 4c 89 e2 48 c7 c7 c0 a0 fd 84 e8 d2 a7 1d ff 0f 0b 48 c7 c7 20 a1 fd 84 e8 c4 a7 1d ff 0f 0b 48 c7 c7 80 a1 fd 84 e8 b6 a7 1d ff <0f> 0b 48 c7 c7 e0 a1 fd 84 e8 a8 a7 1d ff 0f 0b 48 89 df 48 89 
RIP: __list_del_entry_valid+0xef/0x150 lib/list_debug.c:51 RSP: ffff8801d56beef8
---[ end trace 7278482e20440d9e ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled