panic() at panic+0x154 sys/kern/subr_prf.c:208 fifo_badop(ffffffff817a7612) at fifo_badop+0x12 sys/miscfs/fifofs/fifo_vnops.c:491 VOP_STRATEGY(810e5c952a53c4fb) at VOP_STRATEGY+0xa3 sys/kern/vfs_vops.c:715 bwrite(a60dd8767663f925) at bwrite+0x1f5 sys/kern/vfs_bio.c:742 VOP_BWRITE(ffa5c0c6e4a5f991) at VOP_BWRITE+0x54 sys/kern/vfs_vops.c:727 ufs_mkdir(bc324a8a4faa440d) at ufs_mkdir+0x73f sys/ufs/ufs/ufs_vnops.c:1250 VOP_MKDIR(b8f92dc3e873fbc,ffff8000ffff8260,1ed,ffffff9c) at VOP_MKDIR+0x72 sys/kern/vfs_vops.c:445 domkdirat(56bf7eda61b586b6,2,ffff8000ffff8260,ffff800014a1a2d0) at domkdirat+0x12a sys/kern/vfs_syscalls.c:2881 syscall(c549e9ca5338300e) at syscall+0x528 Xsyscall(6,88,7f7ffffd5580,88,0,7f7ffffd55c0) at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffd55f0, 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+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic() at panic+0x154 sys/kern/subr_prf.c:208 fifo_badop(ffffffff817a7612) at fifo_badop+0x12 sys/miscfs/fifofs/fifo_vnops.c:491 VOP_STRATEGY(810e5c952a53c4fb) at VOP_STRATEGY+0xa3 sys/kern/vfs_vops.c:715 bwrite(a60dd8767663f925) at bwrite+0x1f5 sys/kern/vfs_bio.c:742 VOP_BWRITE(ffa5c0c6e4a5f991) at VOP_BWRITE+0x54 sys/kern/vfs_vops.c:727 ufs_mkdir(bc324a8a4faa440d) at ufs_mkdir+0x73f sys/ufs/ufs/ufs_vnops.c:1250 VOP_MKDIR(b8f92dc3e873fbc,ffff8000ffff8260,1ed,ffffff9c) at VOP_MKDIR+0x72 sys/kern/vfs_vops.c:445 domkdirat(56bf7eda61b586b6,2,ffff8000ffff8260,ffff800014a1a2d0) at domkdirat+0x12a sys/kern/vfs_syscalls.c:2881 syscall(c549e9ca5338300e) at syscall+0x528 Xsyscall(6,88,7f7ffffd5580,88,0,7f7ffffd55c0) at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffd55f0, count: -11 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff800014a19cd0 rbx 0xffff800014a19d70 rdx 0xffff8000ffff8260 rcx 0 rax 0 r8 0xffffffff819f77b4 kprintf+0x184 r9 0x1 r10 0xffff800014a19ad0 r11 0x9a697b2b21fba4fc r12 0x3000000008 r13 0xffff800014a19ce0 r14 0x100 r15 0x1 rip 0xffffffff81369b08 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff800014a19cc0 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb> show proc PROC (syz-executor0) pid=162947 stat=onproc flags process=2 proc=0 pri=17, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff8000ffff9520,0xffff80001496d2e0 process=0xffff8000ffffa350 user=0xffff800014a15000, vmspace=0xfffffd803f015210 estcpu=36, cpticks=5, pctcpu=0.3 user=0, sys=4, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 80629 180382 1 0 3 0x100083 ttyin getty 44782 358773 0 0 3 0x14200 bored sosplice *37336 162947 72659 0 7 0x2 syz-executor0 48774 39123 72659 0 2 0x2 syz-executor1 72659 495850 70571 0 3 0x82 thrsleep syz-fuzzer 72659 470002 70571 0 3 0x4000082 thrsleep syz-fuzzer 72659 234349 70571 0 3 0x4000082 thrsleep syz-fuzzer 72659 94414 70571 0 3 0x4000082 thrsleep syz-fuzzer 72659 86434 70571 0 3 0x4000082 thrsleep syz-fuzzer 72659 46365 70571 0 3 0x4000082 thrsleep syz-fuzzer 72659 266305 70571 0 3 0x4000082 thrsleep syz-fuzzer 72659 341206 70571 0 3 0x4000082 kqread syz-fuzzer 72659 310298 70571 0 3 0x4000082 thrsleep syz-fuzzer 70571 86521 67164 0 3 0x10008a pause ksh 67164 30169 51052 0 3 0x92 select sshd 51052 265611 1 0 3 0x80 select sshd 71200 25543 95720 73 3 0x100090 kqread syslogd 95720 387245 1 0 3 0x100082 netio syslogd 59246 366719 1 77 3 0x100090 poll dhclient 21883 337429 1 0 3 0x80 poll dhclient 52481 196910 0 0 3 0x14200 pgzero zerothread 43867 254143 0 0 3 0x14200 aiodoned aiodoned 84455 339724 0 0 3 0x14200 syncer update 30410 322840 0 0 3 0x14200 cleaner cleaner 33743 142444 0 0 3 0x14200 reaper reaper 5747 459846 0 0 3 0x14200 pgdaemon pagedaemon 27444 520516 0 0 3 0x14200 bored crynlk 96133 63752 0 0 3 0x14200 bored crypto 66894 409101 0 0 3 0x40014200 acpi0 acpi0 74842 189754 0 0 3 0x14200 bored softnet 69548 142662 0 0 3 0x14200 bored systqmp 65738 9941 0 0 3 0x14200 bored systq 73538 505715 0 0 3 0x40014200 bored softclock 90320 349901 0 0 3 0x40014200 idle0 1 159367 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper