panic: ffs_valloc: dup alloc
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*    18  73252      0           0  0x4000000    0  syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff830af51d) at panic+0x1cf sys/kern/subr_prf.c:198
ffs_inode_alloc(fffffd807402ea58,2000,fffffd807f7d7618,ffff80002a4a2d30) at ffs_inode_alloc+0x96c sys/ufs/ffs/ffs_alloc.c:404
ufs_makeinode(2000,fffffd806b2e7cd8,ffff80002a4a2f50,ffff80002a4a2f80) at ufs_makeinode+0xcb sys/ufs/ufs/ufs_vnops.c:1728
ufs_mknod(ffff80002a4a2df0) at ufs_mknod+0x5b sys/ufs/ufs/ufs_vnops.c:167
VOP_MKNOD(fffffd806b2e7cd8,ffff80002a4a2f50,ffff80002a4a2f80,ffff80002a4a2e80) at VOP_MKNOD+0x102 sys/kern/vfs_vops.c:121
domknodat(ffff80002a4d47b8,ffffff9c,200000c0,2000,d01) at domknodat+0x47e sys/kern/vfs_syscalls.c:1624
syscall(ffff80002a4a3120) at syscall+0x97e sys/arch/amd64/amd64/trap.c:577
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xde38485e680, count: 6
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> 
ddb> set $lines = 0
ddb> set $maxwidth = 0
ddb> show panic
*cpu0: ffs_valloc: dup alloc
ddb> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff830af51d) at panic+0x1cf sys/kern/subr_prf.c:198
ffs_inode_alloc(fffffd807402ea58,2000,fffffd807f7d7618,ffff80002a4a2d30) at ffs_inode_alloc+0x96c sys/ufs/ffs/ffs_alloc.c:404
ufs_makeinode(2000,fffffd806b2e7cd8,ffff80002a4a2f50,ffff80002a4a2f80) at ufs_makeinode+0xcb sys/ufs/ufs/ufs_vnops.c:1728
ufs_mknod(ffff80002a4a2df0) at ufs_mknod+0x5b sys/ufs/ufs/ufs_vnops.c:167
VOP_MKNOD(fffffd806b2e7cd8,ffff80002a4a2f50,ffff80002a4a2f80,ffff80002a4a2e80) at VOP_MKNOD+0x102 sys/kern/vfs_vops.c:121
domknodat(ffff80002a4d47b8,ffffff9c,200000c0,2000,d01) at domknodat+0x47e sys/kern/vfs_syscalls.c:1624
syscall(ffff80002a4a3120) at syscall+0x97e sys/arch/amd64/amd64/trap.c:577
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xde38485e680, count: -9
ddb> show registers
rdi                                0
rsi                              0x1
rbp               0xffff80002a4a2ad0
rbx               0xfffffd805b03aa00
rdx               0xffff8000011771c0
rcx                                0
rax               0xffff80002a4d47b8
r8                                 0
r9                0x8080808080808080
r10