panic: ffs2_balloc: unwind failed
Starting stack trace...
panic(ffffffff83413c0e) at panic+0x1ba sys/kern/subr_prf.c:229
ffs2_balloc(fffff3006b489e00,48001000006,1,fffff30007ffd750,1,ffff80002a863a50) at ffs2_balloc+0x1965
ffs_truncate(fffff3006b489e00,48001000007,0,fffff30007ffd750) at ffs_truncate+0x410 sys/ufs/ffs/ffs_inode.c:185
ufs_setattr(ffff80002a863b70) at ufs_setattr+0x8e0 sys/ufs/ufs/ufs_vnops.c:403
VOP_SETATTR(fffff3006c36e608,ffff80002a863bf8,fffff30007ffd750,ffff80003c8fbca8) at VOP_SETATTR+0x112 sys/kern/vfs_vops.c:210
dotruncate(ffff80003c8fbca8,fffff3006c36e608,48001000007) at dotruncate+0x1da sys/kern/vfs_syscalls.c:2811
sys_ftruncate(ffff80003c8fbca8,ffff80002a863e10,ffff80002a863d60) at sys_ftruncate+0x208 sys/kern/vfs_syscalls.c:2865
syscall(ffff80002a863e10) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a863e10) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xddd26f91240, count: 248
End of stack trace.
syncing disks... done

dump to dev 4,1 not possible
rebooting...
SeaBIOS (version 1.8.2-google)
Total RAM Size = 0x0000000080000000 = 2048 MiB
CPUs found: 2     Max CPUs supported: 2
SeaBIOS (version 1.8.2-google)
Machine UUID baf204d0-9686-8be2-2218-978b30863790
found virtio-scsi at 0:3
virtio-scsi vendor='Google' product='PersistentDisk' rev='1' type=0 removable=0
virtio-scsi blksize=512 sectors=4194304 = 2048 MiB
drive 0x000f2600: PCHS=0/0/0 translation=lba LCHS=520/128/63 s=4194304
Sending Seabios boot VM event.
Booting from Hard Disk 0...
>> OpenBSD/amd64 BOOT 3.67
boot> set $lines = 0
set: syntax error
boot> set $maxwidth = 0
set: syntax error
boot> show panic
boot: illegal argument panic
boot> trace
boot> show registers
boot> show proc
boot> ps
boot> show all locks
boot> show malloc
boot> show all pools
boot> machine ddbcpu 0
machine: syntax error
boot> trace
boot> machine ddbcpu 1
machine: syntax error
boot> trace