R13: 00007f176e10eb48 R14: 00000000004b5e86 R15: 0000000000000000
list_del corruption. prev->next should be ffff8801c790f138, but was 0000000041b58ab3
------------[ 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: 16881 Comm: syz-executor5 Not tainted 4.13.0-rc6+ #45
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d84042c0 task.stack: ffff8801c7908000
RIP: 0010:__list_del_entry_valid+0xef/0x150 lib/list_debug.c:51
RSP: 0018:ffff8801c790eef8 EFLAGS: 00010282
RAX: 0000000000000054 RBX: ffff8801c4137a80 RCX: 0000000000000000
RDX: 0000000000000054 RSI: ffffffff815930de RDI: ffffed0038f21dd3
RBP: ffff8801c790ef10 R08: 0000000000000001 R09: 0000000000000000
R10: ffff8801c790edd8 R11: 0000000000000000 R12: ffff8801c4137a80
R13: dffffc0000000000 R14: ffff8801c3e08700 R15: ffff8801c790f140
FS:  00007f176e130700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001ddbc21000 CR3: 00000001c5771000 CR4: 00000000001406f0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
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:1175 [inline]
 copy_mm+0xde2/0x1247 kernel/fork.c:1229
 copy_process.part.34+0x1ec4/0x4bd0 kernel/fork.c:1735
 copy_process kernel/fork.c:1545 [inline]
 _do_fork+0x1ef/0xfb0 kernel/fork.c:2026
 SYSC_clone kernel/fork.c:2136 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2130
 do_syscall_64+0x26c/0x800 arch/x86/entry/common.c:284
 entry_SYSCALL64_slow_path+0x25/0x25
RIP: 0033:0x4512e9
RSP: 002b:00007f176e12fc08 EFLAGS: 00000216 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 00000000004512e9
RDX: 0000000020f42000 RSI: 0000000020179000 RDI: 0000000000000000
RBP: 00000000000003b0 R08: 0000000020ef4ffc R09: 0000000000000000
R10: 0000000020a6bffc R11: 0000000000000216 R12: 00000000004b65e0
R13: 00000000ffffffff R14: 0000000000000000 R15: 0000000020179000
Code: 4c 89 e2 48 c7 c7 c0 a0 fd 84 e8 e2 c5 1d ff 0f 0b 48 c7 c7 20 a1 fd 84 e8 d4 c5 1d ff 0f 0b 48 c7 c7 80 a1 fd 84 e8 c6 c5 1d ff <0f> 0b 48 c7 c7 e0 a1 fd 84 e8 b8 c5 1d ff 0f 0b 48 89 df 48 89 
RIP: __list_del_entry_valid+0xef/0x150 lib/list_debug.c:51 RSP: ffff8801c790eef8
---[ end trace 8a67e2fc751a198e ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..