panic: witness_warn
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*188618  48414      0           0  0x4000000    0  syz-executor1
 145454  92932      0         0x2      0x480    1  syz-executor1
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399
panic() at panic+0x16c sys/kern/subr_prf.c:208
witness_warn(6b9544808654530a,0,ffff800020bbabd0) at witness_warn+0x6e0 witness_debugger sys/kern/subr_witness.c:2546 [inline]
witness_warn(6b9544808654530a,0,ffff800020bbabd0) at witness_warn+0x6e0 sys/kern/subr_witness.c:1462
userret(f1e6ee0f51a7a44b) at userret+0x361 sys/kern/kern_sig.c:1899
syscall(1607104c276985fb) at syscall+0x680 mi_syscall_return sys/sys/syscall_mi.h:122 [inline]
syscall(1607104c276985fb) at syscall+0x680 sys/arch/amd64/amd64/trap.c:605
Xsyscall(6,5,c,0,3,bd2423490d8) at Xsyscall+0x128
end of kernel
end trace frame: 0xbd4b53d1d10, count: 9
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports.  Insufficient info makes it difficult to find and fix bugs.
ddb{0}> 
ddb{0}> set $lines = 0
ddb{0}> show panic
witness_warn
ddb{0}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399
panic() at panic+0x16c sys/kern/subr_prf.c:208
witness_warn(6b9544808654530a,0,ffff800020bbabd0) at witness_warn+0x6e0 witness_debugger sys/kern/subr_witness.c:2546 [inline]
witness_warn(6b9544808654530a,0,ffff800020bbabd0) at witness_warn+0x6e0 sys/kern/subr_witness.c:1462
userret(f1e6ee0f51a7a44b) at userret+0x361 sys/kern/kern_sig.c:1899
syscall(1607104c276985fb) at syscall+0x680 mi_syscall_return sys/sys/syscall_mi.h:122 [inline]
syscall(1607104c276985fb) at syscall+0x680 sys/arch/amd64/amd64/trap.c:605
Xsyscall(6,5,c,0,3,bd2423490d8) at Xsyscall+0x128
end of kernel
end trace frame: 0xbd4b53d1d10, count: -6
ddb{0}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff800020c8bba0
rbx               0xffff800020c8bc40
rdx               0xffffffff81f2ea76    apollo_pio_rec+0x9bcf
rcx                            0x201
rax                              0x1
r8                0xffffffff810e4f24    kprintf+0x174
r9                               0x1
r10                0x2925f90960a5133
r11               0xde023a2762b06d5a
r12                     0x3000000008
r13               0xffff800020c8bbb0
r14                            0x100
r15                              0x1
rip               0xffffffff8171e6c8    db_enter+0x18
cs                               0x8
rflags                         0x246
rsp               0xffff800020c8bb90
ss                              0x10
db_enter+0x18:  addq    $0x8,%rsp
ddb{0}> show proc
PROC (syz-executor1) pid=188618 stat=onproc
    flags process=0 proc=4000000<THREAD>
    pri=32, usrpri=52, nice=20
    forw=0xffffffffffffffff, list=0xffff800020bba978,0xffff800020bbb798
    process=0xffff800020b953c0 user=0xffff800020c86000, vmspace=0xfffffd807f00db40
    estcpu=36, cpticks=2, pctcpu=0.0
    user=0, sys=2, intr=0
ddb{0}>