panic: vrele: v_writecount != 0 Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 97396 70529 0 0 0 0 syz-executor.0 *463647 70529 0 0 0x4000000 1K syz-executor.0 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff8245fb0e) at panic+0x15e sys/kern/subr_prf.c:218 vrele(fffffd806e2456b0) at vrele+0x197 sys/kern/vfs_subr.c:803 ptmioctl(5100,40287401,ffff8000222db940,3,ffff80002123ca88) at ptmioctl+0x5b9 sys/kern/tty_pty.c:1225 VOP_IOCTL(fffffd806e3afc98,40287401,ffff8000222db940,3,fffffd807f7b78a0,ffff80002123ca88) at VOP_IOCTL+0x9a sys/kern/vfs_vops.c:297 vn_ioctl(fffffd80667894c0,40287401,ffff8000222db940,ffff80002123ca88) at vn_ioctl+0xba sys/kern/vfs_vnops.c:531 sys_ioctl(ffff80002123ca88,ffff8000222dba50,ffff8000222dbaa0) at sys_ioctl+0x4b0 syscall(ffff8000222dbb20) at syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222dbb20) at syscall+0x4a1 sys/arch/amd64/amd64/trap.c:590 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xfabf47ea260, 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.