panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 955 Stopped at db_enter+0x25: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 163658 53005 0 0 0 0 syz-executor * 40599 53005 0 0 0x4000000 1K syz-executor db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff833b1079) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833f126e,ffffffff833fefd9,3bb,ffffffff834292dd) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c42f4e8,ffffffff833aad86) at refcnt_finalize+0x1db sys/kern/kern_synch.c:956 pppx_if_destroy(ffff800037ffd000,ffff80003c42f4e0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,2,2000,ffff800033bec2b8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c42b2d0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c51d880,2,fffffd80097fd6e8,ffff800033bec2b8) at VOP_CLOSE+0x132 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806b948870,ffff800033bec2b8) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806b948870,ffff800033bec2b8) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806b948870,ffff800033bec2b8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806b948870,ffff800033bec2b8) at closef+0x192 sys/kern/kern_descrip.c:1264 finishdup(ffff800033bec2b8,fffffd806b9480f0,5,6,ffff80003c42b530,2) at finishdup+0x478 sys/kern/kern_descrip.c:688 syscall(ffff80003c42b5e0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c42b5e0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xfa6251bc960, count: 1 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{1}> ddb{1}> set $lines = 0 ddb{1}> set $maxwidth = 0 ddb{1}> show panic *cpu1: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 955 ddb{1}> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff833b1079) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833f126e,ffffffff833fefd9,3bb,ffffffff834292dd) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c42f4e8,ffffffff833aad86) at refcnt_finalize+0x1db sys/kern/kern_synch.c:956 pppx_if_destroy(ffff800037ffd000,ffff80003c42f4e0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,2,2000,ffff800033bec2b8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c42b2d0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c51d880,2,fffffd80097fd6e8,ffff800033bec2b8) at VOP_CLOSE+0x132 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806b948870,ffff800033bec2b8) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806b948870,ffff800033bec2b8) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806b948870,ffff800033bec2b8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806b948870,ffff800033bec2b8) at closef+0x192 sys/kern/kern_descrip.c:1264 finishdup(ffff800033bec2b8,fffffd806b9480f0,5,6,ffff80003c42b530,2) at finishdup+0x478 sys/kern/kern_descrip.c:688 syscall(ffff80003c42b5e0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c42b5e0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xfa6251bc960, count: -14 ddb{1}> show registers rdi 0 rsi 0x1 rbp 0xffff80003c42b0a0 rbx 0xffff8000299eee07 rdx 0xffff80000148bc40 rcx 0xffff800033bec2b8 rax 0xffff8000299edff0 r8 0x101010101010101 r9 0x8080808080808080 r10 0xf00f8b78d45c12b2 r11 0xe338280435b32ad8 r12 0xffff8000299eec08 r13 0 r14 0 r15 0x1 rip 0xffffffff817a87c5 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c42b090 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb{1}> show proc PROC (syz-executor) tid=40599 pid=53005 tcnt=3 stat=onproc flags process=0 proc=4000000 runpri=32, usrpri=57, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0 forw=0xffffffffffffffff, list=0xffff800033bec550,0xffffffff838e8588 process=0xffff80003c41c4f0 user=0xffff80003c426000, vmspace=0xfffffd8072fa53e8 estcpu=7, cpticks=1, pctcpu=0.0, user=0, sys=1, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 5272 169664 81790 0 2 0 syz-executor 5272 301293 81790 0 3 0x4000080 fsleep syz-executor 85203 426777 39106 0 2 0 syz-executor 85203 436952 39106 0 3 0x4000080 fsleep syz-executor 15201 19308 1349 0 3 0x80 nanoslp syz-executor 15201 236066 1349 0 3 0x4000080 kqpoll syz-executor 15201 374583 1349 0 3 0x4000080 fsleep syz-executor 89026 470045 98953 0 2 0 syz-executor 89026 218051 98953 0 3 0x4000080 fsleep syz-executor 89026 198170 98953 0 3 0x4000080 fsleep syz-executor 60133 52494 76358 60928 2 0x10 syz-executor 60133 193448 76358 60928 3 0x4000090 sbwait syz-executor 53005 163658 1110 0 7 0 syz-executor 53005 289522 1110 0 3 0x4000000 smrbar syz-executor *53005 40599 1110 0 7 0x4000000 syz-executor 9681 515671 30096 0 2 0 syz-executor 9681 136326 30096 0 3 0x4000080 fsleep syz-executor 60185 139010 74260 0 2 0 syz-executor 60185 269272 74260 0 3 0x4000080 fsleep syz-executor 39106 445499 33821 0 3 0x82 nanoslp syz-executor 1110 14282 33821 0 3 0x82 nanoslp syz-executor 30096 7134 33821 0 3 0x82 nanoslp syz-executor 81790 341330 33821 0 3 0x82 nanoslp syz-executor 98953 15438 33821 0 3 0x82 nanoslp syz-executor 74260 272020 33821 0 3 0x82 nanoslp syz-executor 1349 372130 33821 0 3 0x82 nanoslp syz-executor 76358 211970 33821 0 3 0x82 nanoslp syz-executor 33821 307915 56944 0 3 0x82 kqread syz-executor 56944 80889 7090 0 3 0x10008a sigsusp ksh 7090 166080 65328 0 3 0x98 kqread sshd-session 65328 246867 83840 0 3 0x92 kqread sshd-session 7059 299879 1 0 3 0x100083 ttyin getty 83840 107982 1 0 3 0x88 kqread sshd 85081 428138 86099 74 3 0x1100092 bpf pflogd 86099 174522 1 0 3 0x80 sbwait pflogd 66273 209062 82857 73 3 0x1100090 kqread syslogd 82857 23644 1 0 3 0x100082 sbwait syslogd 64235 301518 1 0 3 0x100080 kqread resolvd 48082 346842 85511 77 3 0x100092 kqread dhcpleased 29934 226952 85511 77 3 0x100092 kqread dhcpleased 85511 325800 1 0 3 0x80 kqread dhcpleased 88942 396524 0 0 3 0x14200 bored smr 21342 355274 0 0 2 0x14200 zerothread 42418 433635 0 0 3 0x14200 aiodoned aiodoned 87245 177057 0 0 3 0x14200 syncer update 62194 67987 0 0 3 0x14200 cleaner cleaner 80556 247835 0 0 3 0x14200 reaper reaper 15422 179896 0 0 3 0x14200 pgdaemon pagedaemon 22594 314715 0 0 3 0x14200 bored viomb 91034 77795 0 0 3 0x40014200 acpi0 acpi0 67455 131957 0 0 3 0x40014200 idle1 86378 387909 0 0 3 0x14200 bored softnet1 45614 95519 0 0 3 0x14200 bored softnet0 41741 263762 0 0 3 0x14200 smrbar systqmp 8206 505568 0 0 3 0x14200 bored systq 45028 221948 0 0 3 0x14200 tmoslp softclockmp 37672 174717 0 0 3 0x40014200 tmoslp softclock 38517 236900 0 0 3 0x40014200 idle0 1 351427 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{1}> show all locks Process 53005 (syz-executor) thread 0xffff800033bec2b8 (40599) exclusive kernel_lock &kernel_lock r = 0 (0xffffffff8395a208) #0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline] #0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160 #1 vn_closefile+0x41 sys/kern/vfs_vnops.c:608 #2 fdrop+0x121 sys/kern/kern_descrip.c:1280 #3 closef+0x192 sys/kern/kern_descrip.c:1264 #4 finishdup+0x478 sys/kern/kern_descrip.c:688 #5 syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] #5 syscall+0xbd4 sys/arch/amd64/amd64/trap.c:775 #6 Xsyscall+0x128 Process 41741 (systqmp) thread 0xffff8000ffffe000 (263762) shared rwlock systqmp r = 0 (0xffffffff838ab438) #0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline] #0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160 #1 taskq_thread+0x12a sys/kern/kern_task.c:442 #2 proc_trampoline+0x10 ddb{1}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10220 11323K 11517K 166960K 11350 0 pcb 19 12K 12K 166960K 29 0 rtable 246 8K 8K 166960K 360 0 pf 37 18K 18K 166960K 52 0 ifaddr 45 7K 7K 166960K 49 0 ifgroup 60 2K 2K 166960K 64 0 sysctl 1 1K 9K 166960K 5 0 counters 74 37K 37K 166960K 84 0 ioctlops 0 0K 4K 166960K 1553 0 iov 1 8K 8K 166960K 1 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1349 85K 85K 166960K 1391 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 1K 166960K 2 0 VM map 2 1K 1K 166960K 2 0 sem 5 0K 0K 166960K 6 0 dirhash 12 2K 2K 166960K 12 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 93K 166960K 163 0 proc 72 115K 147K 166960K 532 0 subproc 72 4K 4K 166960K 73 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 2 0K 0K 166960K 9 0 in_multi 100 7K 7K 166960K 101 0 ether_multi 1 0K 0K 166960K 1 0 mrt 1 0K 0K 166960K 1 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 61 281K 281K 166960K 61 0 exec 0 0K 1K 166960K 379 0 fusefs mount 1 32K 32K 166960K 1 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 249 167K 177K 166960K 3264 0 UVM aobj 3 2K 2K 166960K 3 0 pinsyscall 43 86K 106K 166960K 1287 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 2 0 NDP 29 2K 2K 166960K 31 0 temp 71 8679K 8743K 166960K 4252 0 kqueue 15 24K 26K 166960K 28 0 SYN cache 2 16K 16K 166960K 2 0 ddb{1}> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle plcache 128 26 0 0 1 0 1 1 0 8 0 rtpcb 120 34 0 30 1 0 1 1 0 8 0 rtentry 176 113 0 1 6 0 6 6 0 8 0 unpcb 144 56 0 32 1 0 1 1 0 8 0 syncache 336 3 0 3 1 0 1 1 0 8 1 tcpcb 736 16 0 10 1 0 1 1 0 8 0 arp 136 18 0 0 1 0 1 1 0 8 0 inpcb 328 96 0 83 2 0 2 2 0 8 0 nd6 152 24 0 0 1 0 1 1 0 8 0 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1192 6 0 5 1 0 1 1 0 8 0 pppxif 1504 1 0 0 1 0 1 1 0 8 0 pfosfp 40 1428 0 1005 5 0 5 5 0 8 0 pfosfpen 112 1428 0 714 21 0 21 21 0 8 0 pfstitem 24 17 0 0 1 0 1 1 0 8 0 pfstkey 128 17 0 0 1 0 1 1 0 8 0 pfstate 448 17 0 0 2 0 2 2 0 8 0 pfrule 1344 21 0 16 2 1 1 2 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 465 0 6 30 0 30 30 0 8 0 art_table 40 466 0 6 5 0 5 5 0 8 0 art_node 32 113 0 11 1 0 1 1 0 8 0 sysvmsgpl 40 1 0 1 1 0 1 1 0 8 1 semupl 112 1 0 1 1 0 1 1 0 8 1 semapl 112 3 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1616 0 98 96 0 96 96 0 8 0 ffsino 296 1616 0 98 118 0 118 118 0 8 0 nchpl 144 1844 0 141 64 0 64 64 0 8 0 rtmask 32 3 0 3 1 0 1 1 0 8 1 vnodes 216 1719 0 0 96 0 96 96 0 8 0 namei 1024 5915 0 5915 2 0 2 2 0 8 2 percpumem 16 57 0 5 1 0 1 1 0 8 0 kstatmem 264 32 0 4 3 0 3 3 0 8 0 scxspl 216 5938 0 5938 3 1 2 2 1 8 2 plimitpl 152 30 0 12 1 0 1 1 0 8 0 sigapl 424 471 0 423 7 0 7 7 0 8 0 knotepl 120 57 0 0 2 0 2 2 0 8 0 kqueuepl 224 35 0 19 1 0 1 1 0 8 0 pipepl 344 121 0 93 3 0 3 3 0 8 0 fdescpl 528 455 0 423 3 0 3 3 0 8 0 filepl 160 1834 0 1594 11 0 11 11 0 8 1 lockfpl 104 75 0 72 1 0 1 1 0 8 0 lockfspl 48 7 0 4 1 0 1 1 0 8 0 sessionpl 144 22 0 13 1 0 1 1 0 8 0 pgrppl 48 30 0 13 1 0 1 1 0 8 0 ucredpl 104 115 0 101 1 0 1 1 0 8 0 zombiepl 144 423 0 423 1 0 1 1 0 8 1 processpl 1232 471 0 423 5 0 5 5 0 8 0 procpl 664 517 0 458 5 0 5 5 0 8 0 sockpl 752 186 0 145 5 0 5 5 0 8 0 mcl64k 65536 2 0 0 1 0 1 1 0 8 0 mcl8k 8192 2 0 0 1 0 1 1 0 8 0 mcl4k 4096 114 0 0 15 0 15 15 0 8 0 mcl2k 2048 24 0 0 3 0 3 3 0 8 0 mtagpl 96 6 0 0 1 0 1 1 0 8 0 mbufpl 256 204 0 0 13 0 13 13 0 8 0 bufpl 280 2350 0 130 159 0 159 159 0 8 0 anonpl 32 3971 0 0 32 0 32 32 0 246 0 amapchunkpl 152 9261 0 8745 20 0 20 20 0 158 0 amappl16 200 2180 0 2154 5 0 5 5 0 8 3 amappl15 192 107 0 107 1 0 1 1 0 8 1 amappl14 184 18 0 18 2 1 1 1 0 8 1 amappl13 176 422 0 421 1 0 1 1 0 8 0 amappl12 168 834 0 790 4 1 3 3 0 8 0 amappl11 160 3 0 3 1 0 1 1 0 8 1 amappl10 152 52 0 38 1 0 1 1 0 8 0 amappl9 144 250 0 249 1 0 1 1 0 8 0 amappl8 136 27 0 25 1 0 1 1 0 8 0 amappl7 128 103 0 102 1 0 1 1 0 8 0 amappl6 120 279 0 266 1 0 1 1 0 8 0 amappl5 112 77 0 67 1 0 1 1 0 8 0 amappl4 104 411 0 382 1 0 1 1 0 8 0 amappl3 96 1492 0 1378 4 1 3 3 0 8 0 amappl2 88 522 0 463 2 0 2 2 0 8 0 amappl1 80 9108 0 8502 15 0 15 15 0 8 1 amappl 88 2537 0 2366 4 0 4 4 0 92 0 uvmvnodes 80 98 0 0 2 0 2 2 0 8 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 72 2 0 0 1 0 1 1 0 8 0 uaddrrnd 24 455 0 423 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 455 0 423 1 0 1 1 0 8 0 vmmpekpl 168 5520 0 5485 2 0 2 2 0 8 0 vmmpepl 168 37239 0 35270 87 0 87 87 0 357 1 vmsppl 488 454 0 423 5 0 5 5 0 8 0 rwobjpl 80 13891 0 12861 24 0 24 24 0 8 1 pdppl 4096 917 0 846 97 12 85 85 0 8 14 pvpl 32 9572 0 0 78 0 78 78 0 265 0 pmappl 256 454 0 423 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 272 0 14 8 0 8 8 0 8 0 ddb{1}> machine ddbcpu 0 Stopped at x86_ipi_db+0x27: addq $0x8,%rsp x86_ipi_db(ffffffff83802ff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 __mp_lock(ffffffff8395a000) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:142 [inline] __mp_lock(ffffffff8395a000) at __mp_lock+0x192 sys/kern/kern_lock.c:173 softintr_dispatch(0) at softintr_dispatch+0x125 sys/kern/kern_softintr.c:83 dosoftint(0) at dosoftint+0x54 sys/arch/amd64/amd64/intr.c:862 Xsoftclock() at Xsoftclock+0x27 end of kernel end trace frame: 0x76b4b5ee69e0, count: 8 ddb{0}> trace x86_ipi_db(ffffffff83802ff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 __mp_lock(ffffffff8395a000) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:142 [inline] __mp_lock(ffffffff8395a000) at __mp_lock+0x192 sys/kern/kern_lock.c:173 softintr_dispatch(0) at softintr_dispatch+0x125 sys/kern/kern_softintr.c:83 dosoftint(0) at dosoftint+0x54 sys/arch/amd64/amd64/intr.c:862 Xsoftclock() at Xsoftclock+0x27 end of kernel end trace frame: 0x76b4b5ee69e0, count: -7 ddb{0}> machine ddbcpu 1 Stopped at db_enter+0x25: addq $0x8,%rsp db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff833b1079) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833f126e,ffffffff833fefd9,3bb,ffffffff834292dd) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c42f4e8,ffffffff833aad86) at refcnt_finalize+0x1db sys/kern/kern_synch.c:956 pppx_if_destroy(ffff800037ffd000,ffff80003c42f4e0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,2,2000,ffff800033bec2b8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c42b2d0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c51d880,2,fffffd80097fd6e8,ffff800033bec2b8) at VOP_CLOSE+0x132 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806b948870,ffff800033bec2b8) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806b948870,ffff800033bec2b8) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806b948870,ffff800033bec2b8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806b948870,ffff800033bec2b8) at closef+0x192 sys/kern/kern_descrip.c:1264 finishdup(ffff800033bec2b8,fffffd806b9480f0,5,6,ffff80003c42b530,2) at finishdup+0x478 sys/kern/kern_descrip.c:688 syscall(ffff80003c42b5e0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c42b5e0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xfa6251bc960, count: 1 ddb{1}> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff833b1079) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833f126e,ffffffff833fefd9,3bb,ffffffff834292dd) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c42f4e8,ffffffff833aad86) at refcnt_finalize+0x1db sys/kern/kern_synch.c:956 pppx_if_destroy(ffff800037ffd000,ffff80003c42f4e0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,2,2000,ffff800033bec2b8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c42b2d0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c51d880,2,fffffd80097fd6e8,ffff800033bec2b8) at VOP_CLOSE+0x132 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806b948870,ffff800033bec2b8) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806b948870,ffff800033bec2b8) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806b948870,ffff800033bec2b8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806b948870,ffff800033bec2b8) at closef+0x192 sys/kern/kern_descrip.c:1264 finishdup(ffff800033bec2b8,fffffd806b9480f0,5,6,ffff80003c42b530,2) at finishdup+0x478 sys/kern/kern_descrip.c:688 syscall(ffff80003c42b5e0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c42b5e0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xfa6251bc960, count: -14