list_del corruption. prev->next should be ffff888210dfa6e0, but was           (null)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:51!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 3639 Comm: systemd-udevd Not tainted 4.14.175-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88808f1d4000 task.stack: ffff88808f1d8000
RIP: 0010:__list_del_entry_valid.cold+0xf/0x55 lib/list_debug.c:51
RSP: 0018:ffff88808f1dfa80 EFLAGS: 00010086
RAX: 0000000000000054 RBX: 0000000000cb3bbd RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffed1011e3bf46
RBP: ffff888210dfa6e0 R08: 0000000000000054 R09: 0000000000000004
R10: ffff88808f1df695 R11: ffff88808f1d4000 R12: ffff88800014a5e0
R13: ffff8880235288e0 R14: ffff888210dfa6e8 R15: dffffc0000000000
FS:  00007fa6f9e3c8c0(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056162af838e8 CR3: 000000008ec6e000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 __list_del_entry include/linux/list.h:117 [inline]
 list_del_rcu include/linux/rculist.h:130 [inline]
 __unhash_process kernel/exit.c:79 [inline]
 __exit_signal kernel/exit.c:155 [inline]
 release_task+0xc8f/0x1430 kernel/exit.c:200
 wait_task_zombie kernel/exit.c:1148 [inline]
 wait_consider_task+0x26a1/0x3030 kernel/exit.c:1375
 do_wait_thread kernel/exit.c:1438 [inline]
 do_wait+0x3e9/0x930 kernel/exit.c:1509
 kernel_wait4+0x103/0x1e0 kernel/exit.c:1652
 SYSC_wait4+0x106/0x110 kernel/exit.c:1664
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x7fa6f8f83b0a
RSP: 002b:00007ffe87808408 EFLAGS: 00000246 ORIG_RAX: 000000000000003d
RAX: ffffffffffffffda RBX: 00007ffe87808460 RCX: 00007fa6f8f83b0a
RDX: 0000000000000001 RSI: 00007ffe87808414 RDI: ffffffffffffffff
RBP: 000056162aeb9a60 R08: 0000000000000008 R09: 000056162af6c958
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe87808414
R13: 0000561628f4a718 R14: 000056162af7d6f0 R15: 0000000000000001
Code: 86 e8 a6 c3 4a fe 0f 0b 48 89 f1 48 c7 c7 00 57 e4 86 4c 89 e6 e8 92 c3 4a fe 0f 0b 48 89 ee 48 c7 c7 a0 58 e4 86 e8 81 c3 4a fe <0f> 0b 4c 89 ea 48 89 ee 48 c7 c7 e0 57 e4 86 e8 6d c3 4a fe 0f 
RIP: __list_del_entry_valid.cold+0xf/0x55 lib/list_debug.c:51 RSP: ffff88808f1dfa80
---[ end trace be9e62b7fe959d5f ]---