panic() at panic+0x147 sys/kern/subr_prf.c:208 fifo_badop(ffffffff8142aa62) at fifo_badop+0x12 sys/miscfs/fifofs/fifo_vnops.c:491 VOP_STRATEGY(ffffff0004898900) at VOP_STRATEGY+0x6b sys/kern/vfs_vops.c:715 bwrite(ffff800014ad0940) at bwrite+0x195 sys/kern/vfs_bio.c:742 VOP_BWRITE(ffffff0030d304c0) at VOP_BWRITE+0x47 sys/kern/vfs_vops.c:727 ufs_mkdir(ffffffff81e21db8) at ufs_mkdir+0x5a9 sys/ufs/ufs/ufs_vnops.c:1247 VOP_MKDIR(ffff800014a33c30,1ed,ffffff9c,ffff800014ad08f8) at VOP_MKDIR+0x65 sys/kern/vfs_vops.c:445 domkdirat(ffff800014ad0b30,ffff800014a33c30,ffff800014a15660,880) at domkdirat+0x10f sys/kern/vfs_syscalls.c:2861 syscall(0) at syscall+0x3e4 Xsyscall(6,88,7f7ffffe40a0,88,0,7f7ffffe40e0) at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffe4110, count: 4 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> show panic fifo_badop called ddb> trace db_enter() at db_enter+0xa sys/arch/amd64/amd64/db_interface.c:399 panic() at panic+0x147 sys/kern/subr_prf.c:208 fifo_badop(ffffffff8142aa62) at fifo_badop+0x12 sys/miscfs/fifofs/fifo_vnops.c:491 VOP_STRATEGY(ffffff0004898900) at VOP_STRATEGY+0x6b sys/kern/vfs_vops.c:715 bwrite(ffff800014ad0940) at bwrite+0x195 sys/kern/vfs_bio.c:742 VOP_BWRITE(ffffff0030d304c0) at VOP_BWRITE+0x47 sys/kern/vfs_vops.c:727 ufs_mkdir(ffffffff81e21db8) at ufs_mkdir+0x5a9 sys/ufs/ufs/ufs_vnops.c:1247 VOP_MKDIR(ffff800014a33c30,1ed,ffffff9c,ffff800014ad08f8) at VOP_MKDIR+0x65 sys/kern/vfs_vops.c:445 domkdirat(ffff800014ad0b30,ffff800014a33c30,ffff800014a15660,880) at domkdirat+0x10f sys/kern/vfs_syscalls.c:2861 syscall(0) at syscall+0x3e4 Xsyscall(6,88,7f7ffffe40a0,88,0,7f7ffffe40e0) at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffe4110, count: -11 ddb> show registers rdi 0xffffffff81e1fa20 kprintf_mutex rsi 0x7fff877e rbp 0xffff800014ad0580 rbx 0xffff800014ad0620 rdx 0xc rcx 0xffffffff81ec6ff0 net_tick_to rax 0 r8 0xffff800014ad0550 r9 0 r10 0xffff800014ad03b8 r11 0x8 r12 0x3000000008 r13 0xffff800014ad0590 r14 0x100 r15 0xffffffff81c2e524 apollo_udma66_tim+0x4d22 rip 0xffffffff8136e03a db_enter+0xa cs 0x8 rflags 0x246 rsp 0xffff800014ad0580 ss 0x10 db_enter+0xa: popq %rbp ddb> show proc PROC (syz-executor0) pid=194595 stat=onproc flags process=2 proc=0 pri=17, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff800014a339d8,0xffff8000ffffd2d8 process=0xffff800014a15660 user=0xffff800014acb000, vmspace=0xffffff003f12b318 estcpu=36, cpticks=5, pctcpu=0.0 user=0, sys=5, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 68248 221622 1 0 3 0x100083 ttyin getty 43904 462737 0 0 3 0x14200 bored sosplice *11850 194595 86220 0 7 0x2 syz-executor0 4064 146557 86220 0 2 0x2 syz-executor1 86220 36730 90324 0 3 0x82 thrsleep syz-fuzzer 86220 200583 90324 0 2 0x4000482 syz-fuzzer 86220 357396 90324 0 3 0x4000082 thrsleep syz-fuzzer 86220 243189 90324 0 3 0x4000082 thrsleep syz-fuzzer 86220 325036 90324 0 3 0x4000082 thrsleep syz-fuzzer 86220 115505 90324 0 3 0x4000082 thrsleep syz-fuzzer 86220 505910 90324 0 3 0x4000082 kqread syz-fuzzer 90324 10344 18482 0 3 0x10008a pause ksh 18482 226880 93288 0 3 0x92 select sshd 93288 222101 1 0 3 0x80 select sshd 20228 347456 4801 73 3 0x100090 kqread syslogd 4801 464457 1 0 3 0x100082 netio syslogd 96865 145346 1 77 3 0x100090 poll dhclient 37673 204913 1 0 3 0x80 poll dhclient 18638 375598 0 0 3 0x14200 pgzero zerothread 79861 431684 0 0 3 0x14200 aiodoned aiodoned 43469 416972 0 0 3 0x14200 syncer update 13176 36617 0 0 3 0x14200 cleaner cleaner 5977 192520 0 0 3 0x14200 reaper reaper 87844 59427 0 0 3 0x14200 pgdaemon pagedaemon 93353 379205 0 0 3 0x14200 bored crynlk 53567 493365 0 0 3 0x14200 bored crypto 64909 308109 0 0 3 0x40014200 acpi0 acpi0 65553 305200 0 0 3 0x14200 bored softnet 30096 168938 0 0 3 0x14200 bored systqmp 86753 168140 0 0 3 0x14200 bored systq 77252 198839 0 0 3 0x40014200 bored softclock 22988 485594 0 0 3 0x40014200 idle0 1 218691 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper