panic: vrele: v_writecount != 0 Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND * 49880 84196 0 0 0x4000000 0 syz-executor.0 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff8243627a) at panic+0x15e sys/kern/subr_prf.c:218 vrele(fffffd807e1525c8) at vrele+0x187 sys/kern/vfs_subr.c:803 ptmioctl(5100,40287401,ffff80002273b860,3,ffff800021697cf0) at ptmioctl+0x5b9 sys/kern/tty_pty.c:1225 VOP_IOCTL(fffffd807b446050,40287401,ffff80002273b860,3,fffffd807f7b7ae0,ffff800021697cf0) at VOP_IOCTL+0x91 sys/kern/vfs_vops.c:297 vn_ioctl(fffffd807d996b58,40287401,ffff80002273b860,ffff800021697cf0) at vn_ioctl+0xb5 sys/kern/vfs_vnops.c:531 sys_ioctl(ffff800021697cf0,ffff80002273b970,ffff80002273b9c0) at sys_ioctl+0x4ac syscall(ffff80002273ba40) at syscall+0x507 sys/arch/amd64/amd64/trap.c:590 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xbe594a3d0d0, 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 vrele: v_writecount != 0 ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff8243627a) at panic+0x15e sys/kern/subr_prf.c:218 vrele(fffffd807e1525c8) at vrele+0x187 sys/kern/vfs_subr.c:803 ptmioctl(5100,40287401,ffff80002273b860,3,ffff800021697cf0) at ptmioctl+0x5b9 sys/kern/tty_pty.c:1225 VOP_IOCTL(fffffd807b446050,40287401,ffff80002273b860,3,fffffd807f7b7ae0,ffff800021697cf0) at VOP_IOCTL+0x91 sys/kern/vfs_vops.c:297 vn_ioctl(fffffd807d996b58,40287401,ffff80002273b860,ffff800021697cf0) at vn_ioctl+0xb5 sys/kern/vfs_vnops.c:531 sys_ioctl(ffff800021697cf0,ffff80002273b970,ffff80002273b9c0) at sys_ioctl+0x4ac syscall(ffff80002273ba40) at syscall+0x507 sys/arch/amd64/amd64/trap.c:590 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xbe594a3d0d0, count: -9 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80002273b2a0 rbx 0xffff80002273b2b0 rdx 0x8b rcx 0x2 rax 0x1 r8 0xffffffff820e50f5 kprintf+0x155 r9 0x1 r10 0x805cdaf9f30f57dd r11 0xf23ef6342d969db7 r12 0x3000000008 r13 0xffff80002273b350 r14 0x100 r15 0x1 rip 0xffffffff81ab85c8 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff80002273b290 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb> show proc PROC (syz-executor.0) pid=49880 stat=onproc flags process=0 proc=4000000 pri=32, usrpri=50, nice=20 forw=0xffffffffffffffff, list=0xffff800021697a50,0xffff800021671a50 process=0xffff80002165d408 user=0xffff800022736000, vmspace=0xfffffd807effc330 estcpu=36, cpticks=3, pctcpu=0.0 user=0, sys=3, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 6917 331414 45026 0 2 0 syz-executor.1 6917 284627 45026 0 3 0x4000080 fsleep syz-executor.1 84196 303412 29979 0 2 0 syz-executor.0 *84196 49880 29979 0 7 0x4000000 syz-executor.0 29979 262381 36872 0 2 0x482 syz-executor.0 45026 417809 36872 0 2 0x482 syz-executor.1 36872 314068 82000 0 3 0x82 thrsleep syz-fuzzer 36872 440627 82000 0 3 0x4000082 thrsleep syz-fuzzer 36872 380727 82000 0 3 0x4000082 thrsleep syz-fuzzer 36872 116579 82000 0 3 0x4000082 thrsleep syz-fuzzer 36872 458183 82000 0 3 0x4000082 thrsleep syz-fuzzer 36872 89546 82000 0 3 0x4000082 kqread syz-fuzzer 36872 145360 82000 0 3 0x4000082 thrsleep syz-fuzzer 82000 350466 52287 0 3 0x10008a sigsusp ksh 52287 202174 41262 0 3 0x92 select sshd 14018 366307 1 0 3 0x100083 ttyin getty 41262 521102 1 0 3 0x80 select sshd 22548 511249 11668 73 3 0x100090 kqread syslogd 11668 307318 1 0 3 0x100082 netio syslogd 53339 205128 1 77 3 0x100090 poll dhclient 62894 263954 1 0 3 0x80 poll dhclient 83083 173261 0 0 3 0x14200 bored smr 28170 219257 0 0 2 0x14200 zerothread 19839 36845 0 0 3 0x14200 aiodoned aiodoned 42585 462422 0 0 3 0x14200 syncer update 24782 518058 0 0 3 0x14200 cleaner cleaner 58193 343135 0 0 3 0x14200 reaper reaper 83893 37428 0 0 3 0x14200 pgdaemon pagedaemon 40586 519377 0 0 3 0x14200 bored crynlk 92049 477592 0 0 3 0x14200 bored crypto 19169 472871 0 0 3 0x14200 bored viomb 86983 456239 0 0 3 0x40014200 acpi0 acpi0 78522 132556 0 0 3 0x14200 bored softnet 14930 30748 0 0 3 0x14200 bored systqmp 15122 396886 0 0 3 0x14200 bored systq 56826 69918 0 0 3 0x40014200 bored softclock 38546 308977 0 0 3 0x40014200 idle0 1 168734 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb> show all locks No such command ddb> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 9466 6342K 6342K 78643K 10556 0 pcb 13 8K 8K 78643K 13 0 rtable 105 3K 3K 78643K 189 0 ifaddr 39 10K 10K 78643K 39 0 counters 21 16K 16K 78643K 21 0 ioctlops 0 0K 2K 78643K 15 0 mount 1 1K 1K 78643K 1 0 vnodes 1216 76K 76K 78643K 1221 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 1K 78643K 2 0 VM map 2 0K 0K 78643K 2 0 sem 2 0K 0K 78643K 2 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12598 0 file desc 6 17K 25K 78643K 36 0 proc 47 38K 54K 78643K 364 0 subproc 32 2K 2K 78643K 34 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 ip_moptions 1 0K 0K 78643K 1 0 in_multi 33 2K 2K 78643K 33 0 ether_multi 1 0K 0K 78643K 1 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 37 175K 175K 78643K 37 0 exec 0 0K 2K 78643K 317 0 pagedep 1 8K 8K 78643K 1 0 inodedep 1 32K 32K 78643K 1 0 newblk 1 0K 0K 78643K 1 0 VM swap 7 26K 26K 78643K 7 0 UVM amap 112 25K 26K 78643K 700 0 UVM aobj 3 2K 2K 78643K 3 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 NDP 9 0K 0K 78643K 9 0 temp 61 3963K 4025K 78643K 1795 0 kqueue 3 4K 4K 78643K 3 0 SYN cache 2 16K 16K 78643K 2 0 ddb> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle arp 64 6 0 0 1 0 1 1 0 8 0 rtpcb 120 19 0 17 1 0 1 1 0 8 0 rtentry 112 45 0 1 2 0 2 2 0 8 0 unpcb 120 23 0 15 1 0 1 1 0 8 0 syncache 296 4 0 4 1 1 0 1 0 8 0 tcpqe 32 910 0 910 1 0 1 1 0 8 1 tcpcb 736 12 0 6 1 0 1 1 0 8 0 inpcb 304 34 0 26 1 0 1 1 0 8 0 nd6 48 6 0 0 1 0 1 1 0 8 0 kcovpl 48 2 0 0 1 0 1 1 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 188 0 0 12 0 12 12 0 8 0 art_table 32 189 0 0 2 0 2 2 0 8 0 art_node 16 44 0 4 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1417 0 21 88 0 88 88 0 8 0 ffsino 240 1417 0 21 83 0 83 83 0 8 0 nchpl 144 1636 0 36 60 0 60 60 0 8 0 uvmvnodes 72 1460 0 0 27 0 27 27 0 8 0 vnodes 224 1460 0 0 86 0 86 86 0 8 0 namei 1024 3982 0 3982 2 1 1 1 0 8 1 scxspl 216 4691 0 4691 9 1 8 8 0 8 8 plimitpl 152 16 0 8 1 0 1 1 0 8 0 sigapl 424 223 0 193 4 0 4 4 0 8 0 futexpl 56 12 0 11 1 0 1 1 0 8 0 knotepl 112 62 0 42 1 0 1 1 0 8 0 kqueuepl 168 2 0 0 1 0 1 1 0 8 0 pipepl 304 69 0 58 2 1 1 1 0 8 0 fdescpl 432 208 0 193 2 0 2 2 0 8 0 filepl 120 971 0 869 4 0 4 4 0 8 0 lockfpl 104 5 0 4 1 0 1 1 0 8 0 lockfspl 48 3 0 2 1 0 1 1 0 8 0 sessionpl 144 17 0 7 1 0 1 1 0 8 0 pgrppl 48 17 0 7 1 0 1 1 0 8 0 ucredpl 96 57 0 50 1 0 1 1 0 8 0 zombiepl 144 193 0 193 3 2 1 1 0 8 1 processpl 1016 223 0 193 5 0 5 5 0 8 1 procpl 672 231 0 193 4 0 4 4 0 8 0 sockpl 432 76 0 58 4 1 3 3 0 8 0 mcl4k 4096 8 0 8 1 1 0 1 0 8 0 mcl2k 2048 173521 0 173436 39 9 30 30 0 8 16 mtagpl 96 2 0 2 1 1 0 1 0 8 0 mbufpl 256 187618 0 187455 19 3 16 16 0 8 5 bufpl 280 3245 0 169 220 0 220 220 0 8 0 anonpl 24 40046 0 20464 122 3 119 119 0 188 1 amapchunkpl 152 1303 0 898 18 0 18 18 0 158 2 amappl16 200 926 0 96 44 0 44 44 0 8 0 amappl15 192 5 0 0 1 0 1 1 0 8 0 amappl14 184 24 0 18 1 0 1 1 0 8 0 amappl13 176 25 0 22 2 1 1 1 0 8 0 amappl12 168 9 0 8 1 0 1 1 0 8 0 amappl11 160 50 0 39 1 0 1 1 0 8 0 amappl10 152 12 0 7 1 0 1 1 0 8 0 amappl9 144 289 0 287 2 1 1 1 0 8 0 amappl8 136 109 0 82 2 0 2 2 0 8 1 amappl7 128 218 0 208 1 0 1 1 0 8 0 amappl6 120 64 0 54 1 0 1 1 0 8 0 amappl5 112 348 0 333 1 0 1 1 0 8 0 amappl4 104 242 0 219 1 0 1 1 0 8 0 amappl3 96 110 0 101 1 0 1 1 0 8 0 amappl2 88 897 0 825 4 2 2 3 0 8 0 amappl1 80 14026 0 13554 27 15 12 20 0 8 1 amappl 88 484 0 410 2 0 2 2 0 92 0 dma4096 4096 1 0 1 1 1 0 1 0 8 0 dma1024 1024 1 0 0 1 0 1 1 0 8 0 dma256 256 6 0 6 1 1 0 1 0 8 0 dma128 128 253 0 253 1 1 0 1 0 8 0 dma64 64 6 0 6 1 1 0 1 0 8 0 dma32 32 7 0 7 1 1 0 1 0 8 0 dma16 16 18 0 17 1 0 1 1 0 8 0 aobjpl 64 2 0 0 1 0 1 1 0 8 0 uaddrrnd 24 208 0 193 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 208 0 193 1 0 1 1 0 8 0 vmmpekpl 168 5800 0 5780 1 0 1 1 0 8 0 vmmpepl 168 33796 0 31730 132 16 116 116 0 357 26 vmsppl 272 207 0 193 2 0 2 2 0 8 1 rwobjpl 24 9393 0 7887 14 4 10 10 0 8 0 pdppl 4096 422 0 386 58 18 40 40 0 8 4 pvpl 32 130108 0 107573 187 3 184 184 0 265 1 pmappl 200 207 0 193 1 0 1 1 0 8 0 extentpl 40 58 0 40 1 0 1 1 0 8 0 phpool 112 317 0 34 9 0 9 9 0 8 0 ddb> machine ddbcpu 0 No such command ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff8243627a) at panic+0x15e sys/kern/subr_prf.c:218 vrele(fffffd807e1525c8) at vrele+0x187 sys/kern/vfs_subr.c:803 ptmioctl(5100,40287401,ffff80002273b860,3,ffff800021697cf0) at ptmioctl+0x5b9 sys/kern/tty_pty.c:1225 VOP_IOCTL(fffffd807b446050,40287401,ffff80002273b860,3,fffffd807f7b7ae0,ffff800021697cf0) at VOP_IOCTL+0x91 sys/kern/vfs_vops.c:297 vn_ioctl(fffffd807d996b58,40287401,ffff80002273b860,ffff800021697cf0) at vn_ioctl+0xb5 sys/kern/vfs_vnops.c:531 sys_ioctl(ffff800021697cf0,ffff80002273b970,ffff80002273b9c0) at sys_ioctl+0x4ac syscall(ffff80002273ba40) at syscall+0x507 sys/arch/amd64/amd64/trap.c:590 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xbe594a3d0d0, count: -9 ddb> machine ddbcpu 1 No such command ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff8243627a) at panic+0x15e sys/kern/subr_prf.c:218 vrele(fffffd807e1525c8) at vrele+0x187 sys/kern/vfs_subr.c:803 ptmioctl(5100,40287401,ffff80002273b860,3,ffff800021697cf0) at ptmioctl+0x5b9 sys/kern/tty_pty.c:1225 VOP_IOCTL(fffffd807b446050,40287401,ffff80002273b860,3,fffffd807f7b7ae0,ffff800021697cf0) at VOP_IOCTL+0x91 sys/kern/vfs_vops.c:297 vn_ioctl(fffffd807d996b58,40287401,ffff80002273b860,ffff800021697cf0) at vn_ioctl+0xb5 sys/kern/vfs_vnops.c:531 sys_ioctl(ffff800021697cf0,ffff80002273b970,ffff80002273b9c0) at sys_ioctl+0x4ac syscall(ffff80002273ba40) at syscall+0x507 sys/arch/amd64/amd64/trap.c:590 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xbe594a3d0d0, count: -9