syzbot

kernel: protection fault trap, code=0
Stopped at      witness_checkorder+0x4f5:       movl    0x10(%r14),%ecx
ddb{1}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
the kernel did not panic
ddb{1}> trace
witness_checkorder(fffffd806f03da30,9,0) at witness_checkorder+0x4f5 witness_lock_order_check sys/kern/subr_witness.c:2442 [inline]
witness_checkorder(fffffd806f03da30,9,0) at witness_checkorder+0x4f5 sys/kern/subr_witness.c:890
mtx_enter(fffffd806f03da20) at mtx_enter+0x3e sys/kern/kern_lock.c:265
knote_remove(ffff80002120cac0,fffffd806f03da20,fffffd806f03daa8,0,0) at knote_remove+0x20d sys/kern/kern_event.c:1881
knote_fdclose(ffff80002120cac0,0) at knote_fdclose+0xae sys/kern/kern_event.c:1934
fdfree(ffff80002120cac0) at fdfree+0xdf sys/kern/kern_descrip.c:1196
exit1(ffff80002120cac0,0,0,1) at exit1+0x3e4 sys/kern/kern_exit.c:206
sys_exit(ffff80002120cac0,ffff800021287710,ffff800021287760) at sys_exit+0x1a sys/kern/kern_exit.c:89
syscall(ffff8000212877e0) at syscall+0x5e2 mi_syscall sys/sys/syscall_mi.h:110 [inline]
syscall(ffff8000212877e0) at syscall+0x5e2 sys/arch/amd64/amd64/trap.c:623
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x72f6daa09f10, count: -9
ddb{1}> show registers
rdi                       0xffffffff
rsi                       0xffffffff
rbp               0xffff8000212874b0
rbx                       0xffffffff
rdx                                0
rcx                              0xc
rax               0xfffffd80031ef000
r8                                 0
r9                               0x1
r10               0xffda7f917f8ca6e8
r11               0x6ef4201807290b66
r12               0xfffffd80031c7300
r13               0xfffffd806f03da30
r14               0xdeafbeaddeafbead
r15               0xfffffd80039b6468
rip               0xffffffff81f47f95    witness_checkorder+0x4f5
cs                               0x8
rflags                       0x10216    __ALIGN_SIZE+0xf216
rsp               0xffff800021287400
ss                              0x10
witness_checkorder+0x4f5:       movl    0x10(%r14),%ecx
ddb{1}> show proc
PROC (syz-executor1279309292) pid=193990 stat=onproc
    flags process=1008<EXITING,SINGLEEXIT> proc=2000<WEXIT>
    pri=0, usrpri=50, nice=20
    forw=0xffffffffffffffff, list=0xffff80002120c2c8,0xffff800021238568
    process=0xffff8000ffff50d8 user=0xffff800021282000, vmspace=0xfffffd8077bff588
    estcpu=0, cpticks=0, pctcpu=0.4
    user=0, sys=0, intr=0
ddb{1}>