panic: witness_warn
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*125966  98055      0      0x1000  0x4080000    0  syz-executor1
 273298  27250     73    0x100010          0    1K syslogd
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(b6380006ff745033,0,ffff800020bba270) at witness_warn+0x6e0 witness_debugger sys/kern/subr_witness.c:2546 [inline]
witness_warn(b6380006ff745033,0,ffff800020bba270) at witness_warn+0x6e0 sys/kern/subr_witness.c:1462
userret(d6813d5fa775f93f) at userret+0x361 sys/kern/kern_sig.c:1899
syscall(fd657b6d84a36906) at syscall+0x680 mi_syscall_return sys/sys/syscall_mi.h:122 [inline]
syscall(fd657b6d84a36906) at syscall+0x680 sys/arch/amd64/amd64/trap.c:605
Xsyscall(6,5,c,0,3,b2c9870b010) at Xsyscall+0x128
end of kernel
end trace frame: 0xb2f096b0280, 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(b6380006ff745033,0,ffff800020bba270) at witness_warn+0x6e0 witness_debugger sys/kern/subr_witness.c:2546 [inline]
witness_warn(b6380006ff745033,0,ffff800020bba270) at witness_warn+0x6e0 sys/kern/subr_witness.c:1462
userret(d6813d5fa775f93f) at userret+0x361 sys/kern/kern_sig.c:1899
syscall(fd657b6d84a36906) at syscall+0x680 mi_syscall_return sys/sys/syscall_mi.h:122 [inline]
syscall(fd657b6d84a36906) at syscall+0x680 sys/arch/amd64/amd64/trap.c:605
Xsyscall(6,5,c,0,3,b2c9870b010) at Xsyscall+0x128
end of kernel
end trace frame: 0xb2f096b0280, count: -6
ddb{0}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff800020c77260
rbx               0xffff800020c77300
rdx               0xffffffff81f2ec1b    cy_pio_rec+0x1a98
rcx                            0x201
rax                              0x1
r8                0xffffffff817cef24    kprintf+0x174
r9                               0x1
r10               0x4c329c8a9d5e7f88
r11               0x297ec2a0266d41ff
r12                     0x3000000008
r13               0xffff800020c77270
r14                            0x100
r15                              0x1
rip               0xffffffff81a668f8    db_enter+0x18
cs                               0x8
rflags                         0x246
rsp               0xffff800020c77250
ss                              0x10
db_enter+0x18:  addq    $0x8,%rsp
ddb{0}>