panic() at panic+0x147 sys/kern/subr_prf.c:208 fifo_badop(ffffffff817b4f62) at fifo_badop+0x12 sys/miscfs/fifofs/fifo_vnops.c:491 VOP_STRATEGY(ffffff0005d84600) at VOP_STRATEGY+0x6b sys/kern/vfs_vops.c:715 bwrite(ffff800014ab0570) at bwrite+0x195 sys/kern/vfs_bio.c:742 VOP_BWRITE(ffffff00317ddb00) at VOP_BWRITE+0x47 sys/kern/vfs_vops.c:727 ufs_mkdir(ffffffff81e1a7f0) at ufs_mkdir+0x5a9 sys/ufs/ufs/ufs_vnops.c:1250 VOP_MKDIR(ffff800014a33528,1ed,ffffff9c,ffff800014ab0528) at VOP_MKDIR+0x65 sys/kern/vfs_vops.c:445 domkdirat(ffff800014ab0760,ffff800014a33528,ffff8000149cf980,880) at domkdirat+0x10f sys/kern/vfs_syscalls.c:2859 syscall(0) at syscall+0x3e4 Xsyscall(6,88,7f7fffffaba0,88,0,7f7fffffabe0) at Xsyscall+0x128 end of kernel end trace frame: 0x7f7fffffac10, 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(ffffffff817b4f62) at fifo_badop+0x12 sys/miscfs/fifofs/fifo_vnops.c:491 VOP_STRATEGY(ffffff0005d84600) at VOP_STRATEGY+0x6b sys/kern/vfs_vops.c:715 bwrite(ffff800014ab0570) at bwrite+0x195 sys/kern/vfs_bio.c:742 VOP_BWRITE(ffffff00317ddb00) at VOP_BWRITE+0x47 sys/kern/vfs_vops.c:727 ufs_mkdir(ffffffff81e1a7f0) at ufs_mkdir+0x5a9 sys/ufs/ufs/ufs_vnops.c:1250 VOP_MKDIR(ffff800014a33528,1ed,ffffff9c,ffff800014ab0528) at VOP_MKDIR+0x65 sys/kern/vfs_vops.c:445 domkdirat(ffff800014ab0760,ffff800014a33528,ffff8000149cf980,880) at domkdirat+0x10f sys/kern/vfs_syscalls.c:2859 syscall(0) at syscall+0x3e4 Xsyscall(6,88,7f7fffffaba0,88,0,7f7fffffabe0) at Xsyscall+0x128 end of kernel end trace frame: 0x7f7fffffac10, count: -11 ddb> show registers rdi 0xffffffff81e0ae68 kprintf_mutex rsi 0x5 rbp 0xffff800014ab01b0 rbx 0xffff800014ab0250 rdx 0x3fd rcx 0 rax 0 r8 0xffff800014ab0180 r9 0 r10 0xffff800014aaffc8 r11 0xffffffff8158eaf0 x86_bus_space_io_read_1 r12 0x3000000008 r13 0xffff800014ab01c0 r14 0x100 r15 0xffffffff81c303e5 apollo_pio_rec+0xba5 rip 0xffffffff81aac5da db_enter+0xa cs 0x8 rflags 0x246 rsp 0xffff800014ab01b0 ss 0x10 db_enter+0xa: popq %rbp ddb> show proc PROC (syz-executor0) pid=46911 stat=onproc flags process=2 proc=0 pri=17, usrpri=79, nice=20 forw=0xffffffffffffffff, list=0xffff800014a32e20,0xffff800014a339e8 process=0xffff8000149cf980 user=0xffff800014aab000, vmspace=0xffffff003f12bb58 estcpu=36, cpticks=2, pctcpu=0.0 user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 43398 445768 1 0 3 0x100083 ttyin getty 40170 269304 0 0 3 0x14200 bored sosplice 10276 160099 49983 0 2 0x2 syz-executor1 * 6458 46911 49983 0 7 0x2 syz-executor0 49983 48402 45328 0 3 0x82 thrsleep syz-fuzzer 49983 513441 45328 0 3 0x4000082 nanosleep syz-fuzzer 49983 448474 45328 0 3 0x4000082 thrsleep syz-fuzzer 49983 57027 45328 0 3 0x4000082 thrsleep syz-fuzzer 49983 245105 45328 0 3 0x4000082 kqread syz-fuzzer 49983 58406 45328 0 3 0x4000082 thrsleep syz-fuzzer 49983 260150 45328 0 3 0x4000082 thrsleep syz-fuzzer 45328 153896 80916 0 3 0x10008a pause ksh 80916 44835 73304 0 3 0x92 select sshd 73304 254265 1 0 3 0x80 select sshd 68549 317277 82623 73 3 0x100090 kqread syslogd 82623 111044 1 0 3 0x100082 netio syslogd 63726 16461 1 77 3 0x100090 poll dhclient 57961 440579 1 0 3 0x80 poll dhclient 75854 482811 0 0 3 0x14200 pgzero zerothread 43598 46960 0 0 3 0x14200 aiodoned aiodoned 27014 418093 0 0 3 0x14200 syncer update 81321 326953 0 0 3 0x14200 cleaner cleaner 80991 404470 0 0 3 0x14200 reaper reaper 42719 203947 0 0 3 0x14200 pgdaemon pagedaemon 9284 358113 0 0 3 0x14200 bored crynlk 97155 63865 0 0 3 0x14200 bored crypto 74544 104188 0 0 3 0x40014200 acpi0 acpi0 11054 214030 0 0 3 0x14200 bored softnet 35812 137519 0 0 3 0x14200 bored systqmp 48862 2577 0 0 3 0x14200 bored systq 53763 92123 0 0 2 0x40014200 softclock 38120 463129 0 0 3 0x40014200 idle0 1 435742 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper