panic: kernel diagnostic assertion "atomic_load_int(&fdp->fd_nuserevents) == 0" failed: file "/syzkaller/managers/setuid/kernel/sys/kern/kern_descrip.c", line 1219
Stopped at db_enter+0x25: addq $0x8,%rsp
TID PID UID PRFLAGS PFLAGS CPU COMMAND
105845 5850 32767 0x10 0x4000000 0 syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff834bd38e) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff834fa2d3,ffffffff834d4427,4c3,ffffffff8348f102) at __assert+0x29 sys/kern/subr_prf.c:-1
fdfree(ffff8000fffe5a18) at fdfree+0x349
exit1(ffff8000fffe5a18,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215
sys_exit(ffff8000fffe5a18,ffff80003539aa60,ffff80003539a9b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1
syscall(ffff80003539aa60) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003539aa60) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x76a8a0841860, count: 7
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 "atomic_load_int(&fdp->fd_nuserevents) == 0" failed: file "/syzkaller/managers/setuid/kernel/sys/kern/kern_descrip.c", line 1219
ddb{1}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff834bd38e) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff834fa2d3,ffffffff834d4427,4c3,ffffffff8348f102) at __assert+0x29 sys/kern/subr_prf.c:-1
fdfree(ffff8000fffe5a18) at fdfree+0x349
exit1(ffff8000fffe5a18,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215
sys_exit(ffff8000fffe5a18,ffff80003539aa60,ffff80003539a9b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1
syscall(ffff80003539aa60) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003539aa60) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x76a8a0841860, count: -8
ddb{1}> show registers
rdi 0
rsi 0x1
rbp 0xffff80003539a7a0
rbx 0xffff80002999ee07
rdx 0
rcx 0xffff8000fffe5a18
rax 0xffff80002999dff0
r8 0x101010101010101
r9 0x8080808080808080
r10 0xe685937e4ae539d4
r11 0xb0f2fcab4cf5f0dc
r12 0xffff80002999ec08
r13 0
r14 0
r15 0x1
rip 0xffffffff81d2d005 db_enter+0x25
cs 0x8
rflags 0x246
rsp 0xffff80003539a790
ss 0x10
db_enter+0x25: addq $0x8,%rsp
ddb{1}> show proc
PROC (syz-executor) tid=91144 pid=88106 tcnt=0 stat=onproc
flags process=1018<EXITING,SUGID,SINGLEEXIT> proc=2000<WEXIT>
runpri=32, usrpri=73, slppri=32, nice=20
wchan=0x0, wmesg=, ps_single=0xffff8000fffe5a18 scnt=-1 ecnt=1
forw=0xffffffffffffffff, list=0xffff8000fffe6a80,0xffff8000fffe62c8
process=0xffff8000fffe0020 user=0xffff800035395000, vmspace=0xffffef007c9cc210
estcpu=23, cpticks=4, pctcpu=0.3, user=0, sys=1, intr=0
ddb{1}> ps
PID TID PPID UID S FLAGS WAIT COMMAND
5850 471975 6656 32767 2 0x10 syz-executor
5850 105845 6656 32767 7 0x4000010 syz-executor
5850 367206 6656 32767 2 0x4000010 syz-executor
17239 300052 12078 32767 2 0x10 syz-executor
75100 414001 79838 32767 2 0x10 syz-executor
75100 342124 79838 32767 2 0x4000010 syz-executor
79009 118943 58202 32767 2 0x10 syz-executor
79009 351706 58202 32767 3 0x4000090 sbwait syz-executor
80855 462289 47567 32767 2 0x10 syz-executor
80855 514976 47567 32767 3 0x4000090 fsleep syz-executor
89981 212624 34595 32767 2 0x10 syz-executor
89981 495056 34595 32767 3 0x4000090 fsleep syz-executor
34595 114655 88243 32767 3 0x90 nanoslp syz-executor
58202 158737 55786 32767 3 0x90 nanoslp syz-executor
31842 120933 46994 32767 3 0x10 biowait syz-executor
47567 193684 26025 32767 3 0x90 nanoslp syz-executor
88833 483253 46513 32767 3 0x90 nanoslp syz-executor
79838 444928 5705 32767 3 0x90 nanoslp syz-executor
6656 105739 30194 32767 3 0x90 nanoslp syz-executor
12078 487906 96551 32767 3 0x90 nanoslp syz-executor
55786 512523 61992 0 3 0x82 wait syz-executor
88243 99708 61992 0 3 0x82 wait syz-executor
26025 9780 61992 0 3 0x82 wait syz-executor
5705 42821 61992 0 3 0x82 wait syz-executor
46513 55059 61992 0 3 0x82 wait syz-executor
96551 404228 61992 0 3 0x82 wait syz-executor
46994 350042 61992 0 3 0x82 wait syz-executor
30194 335490 61992 0 3 0x82 wait syz-executor
61992 468333 82590 0 3 0x82 kqread syz-executor
82590 345875 12026 0 3 0x10008a sigsusp ksh
12026 100428 68353 0 3 0x98 kqread sshd-session
68353 500788 74909 0 3 0x92 kqread sshd-session
91857 438640 1 0 3 0x100083 ttyin getty
74909 23969 1 0 3 0x88 kqread sshd
72855 60724 74324 73 3 0x1100090 kqread syslogd
74324 375395 1 0 3 0x100082 sbwait syslogd
71064 9322 1 0 3 0x100080 kqread resolvd
60524 12444 7828 77 3 0x100092 kqread dhcpleased
77068 301577 7828 77 3 0x100092 kqread dhcpleased
7828 306142 1 0 3 0x80 kqread dhcpleased
9314 489034 0 0 3 0x14200 bored smr
83403 467514 0 0 2 0x14200 zerothread
66394 187038 0 0 3 0x14200 aiodoned aiodoned
45974 234441 0 0 3 0x14200 syncer update
55746 439057 0 0 3 0x14200 cleaner cleaner
5513 123651 0 0 3 0x14200 reaper reaper
91023 460806 0 0 3 0x14200 pgdaemon pagedaemon
88341 492445 0 0 3 0x14200 bored viomb
53164 104231 0 0 3 0x40014200 acpi0 acpi0
58724 485279 0 0 3 0x40014200 idle1
43111 213158 0 0 3 0x14200 bored softnet1
97753 392323 0 0 3 0x14200 bored softnet0
37940 333119 0 0 3 0x14200 smrbar systqmp
64500 196622 0 0 3 0x14200 bored systq
40239 58303 0 0 3 0x14200 tmoslp softclockmp
13701 324311 0 0 3 0x40014200 tmoslp softclock
96274 297773 0 0 3 0x40014200 idle0
1 354651 0 0 3 0x82 wait init
0 0 -1 0 3 0x10200 scheduler swapper
ddb{1}> show all locks
Process 31842 (syz-executor) thread 0xffff8000fffe7248 (120933)
exclusive rrwlock inode r = 0 (0xffffef006c5d91e8)
#0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1 rw_do_enter_write+0x419 sys/kern/kern_rwlock.c:320
#2 rrw_enter+0xc6 sys/kern/kern_rwlock.c:621
#3 VOP_LOCK+0xbd sys/kern/vfs_vops.c:527
#4 ufs_ihashins+0x4f ufs_ihash sys/ufs/ufs/ufs_ihash.c:-1 [inline]
#4 ufs_ihashins+0x4f sys/ufs/ufs/ufs_ihash.c:159
#5 ffs_vget+0x187 sys/ufs/ffs/ffs_vfsops.c:1232
#6 ffs_inode_alloc+0x279 sys/ufs/ffs/ffs_alloc.c:393
#7 ufs_mkdir+0xfc sys/ufs/ufs/ufs_vnops.c:1112
#8 VOP_MKDIR+0x101 sys/kern/vfs_vops.c:394
#9 domkdirat+0x179 sys/kern/vfs_syscalls.c:3062
#10 syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#10 syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
#11 Xsyscall+0x128
exclusive rrwlock inode r = 0 (0xffffef006ce55d68)
#0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1 rw_do_enter_write+0x419 sys/kern/kern_rwlock.c:320
#2 rrw_enter+0xc6 sys/kern/kern_rwlock.c:621
#3 VOP_LOCK+0xbd sys/kern/vfs_vops.c:527
#4 vn_lock+0xa4 sys/kern/vfs_vnops.c:576
#5 vfs_lookup+0x12b sys/kern/vfs_lookup.c:431
#6 namei+0x7c5 sys/kern/vfs_lookup.c:250
#7 domkdirat+0x8b sys/kern/vfs_syscalls.c:3047
#8 syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#8 syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
#9 Xsyscall+0x128
Process 37940 (systqmp) thread 0xffff8000ffffe000 (333119)
shared rwlock systqmp r = 0 (0xffffffff839863c8)
#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 11046 12018K 12034K 166960K 12137 0
pcb 17 12K 12K 166960K 17 0
rtable 237 6K 7K 166960K 347 0
pf 31 16K 16K 166960K 31 0
ifaddr 42 7K 7K 166960K 44 0
ifgroup 50 2K 2K 166960K 50 0
sysctl 1 1K 9K 166960K 5 0
counters 70 37K 37K 166960K 70 0
ioctlops 0 0K 4K 166960K 31 0
iov 0 0K 0K 166960K 1 0
mount 1 1K 1K 166960K 1 0
log 0 0K 0K 166960K 4 0
vnodes 1288 81K 81K 166960K 1354 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 3 0K 0K 166960K 3 0
dirhash 12 2K 2K 166960K 12 0
ACPI 1692 195K 286K 166960K 12470 0
file desc 24 89K 121K 166960K 163 0
proc 58 99K 163K 166960K 496 0
subproc 72 4K 4K 166960K 72 0
NFS srvsock 1 0K 0K 166960K 1 0
NFS daemon 1 16K 16K 166960K 1 0
ip_moptions 0 0K 0K 166960K 2 0
in_multi 99 7K 7K 166960K 101 0
ether_multi 1 0K 0K 166960K 1 0
mrt 0 0K 0K 166960K 1 0
ISOFS mount 1 32K 32K 166960K 1 0
MSDOSFS mount 1 16K 16K 166960K 1 0
ttys 37 175K 175K 166960K 37 0
exec 0 0K 1K 166960K 359 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 229 151K 168K 166960K 3166 0
UVM aobj 3 2K 2K 166960K 3 0
pinsyscall 46 92K 111K 166960K 1246 0
memdesc 1 4K 4K 166960K 1 0
crypto data 1 1K 1K 166960K 1 0
NDP 27 2K 2K 166960K 27 0
temp 35 9111K 9116K 166960K 3730 0
kqueue 16 22K 27K 166960K 38 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 31 1 0 1 1 0 8 0
rtentry 176 111 0 1 5 0 5 5 0 8 0
unpcb 144 49 0 30 1 0 1 1 0 8 0
syncache 336 5 0 5 1 0 1 1 0 8 1
tcpcb 736 16 0 12 1 0 1 1 0 8 0
arp 136 18 0 0 1 0 1 1 0 8 0
inpcb 328 71 0 63 2 0 2 2 0 8 1
nd6 152 24 0 0 1 0 1 1 0 8 0
kcovpl 48 8 0 0 1 0 1 1 0 8 0
art_heap8 4096 1 0 0 1 0 1 1 0 8 0
art_heap4 256 452 0 0 29 0 29 29 0 8 0
art_table 40 453 0 0 5 0 5 5 0 8 0
art_node 32 111 0 10 1 0 1 1 0 8 0
semapl 72 1 0 0 1 0 1 1 0 8 0
dirhash 1024 17 0 0 3 0 3 3 0 8 0
dino2pl 256 1577 0 116 92 0 92 92 0 8 0
ffsino 296 1577 0 116 113 0 113 113 0 8 0
nchpl 144 1794 0 103 63 0 63 63 0 8 0
vnodes 216 1658 0 0 93 0 93 93 0 8 0
namei 1024 5247 0 5246 1 0 1 1 0 8 0
percpumem 16 50 0 0 1 0 1 1 0 8 0
kstatmem 264 25 0 0 2 0 2 2 0 8 0
scxspl 216 6141 0 6140 4 3 1 3 1 8 0
plimitpl 152 40 0 16 2 0 2 2 0 8 1
sigapl 424 455 0 402 7 0 7 7 0 8 0
knotepl 120 292 0 0 9 0 9 9 0 8 0
kqueuepl 224 32 0 21 1 0 1 1 0 8 0
pipepl 344 121 0 94 3 0 3 3 0 8 0
fdescpl 528 439 0 402 3 0 3 3 0 8 0
filepl 160 1515 0 1305 10 0 10 10 0 8 0
lockfpl 104 12 0 10 1 0 1 1 0 8 0
lockfspl 48 6 0 4 1 0 1 1 0 8 0
sessionpl 144 25 0 8 1 0 1 1 0 8 0
pgrppl 48 33 0 8 1 0 1 1 0 8 0
ucredpl 104 122 0 103 1 0 1 1 0 8 0
zombiepl 144 403 0 402 2 1 1 1 0 8 0
processpl 1232 455 0 402 5 0 5 5 0 8 0
procpl 664 488 0 429 6 0 6 6 0 8 0
sockpl 752 154 0 124 4 0 4 4 0 8 0
mcl64k 65536 2 0 0 1 0 1 1 0 8 0
mcl16k 16384 2 0 0 1 0 1 1 0 8 0
mcl8k 8192 2 0 0 1 0 1 1 0 8 0
mcl4k 4096 128 0 0 16 0 16 16 0 8 0
mcl2k 2048 18 0 0 3 0 3 3 0 8 0
mtagpl 96 2 0 0 1 0 1 1 0 8 0
mbufpl 256 190 0 0 12 0 12 12 0 8 0
bufpl 272 2246 0 102 143 0 143 143 0 8 0
anonpl 32 3591 0 0 29 0 29 29 0 246 0
amapchunkpl 152 8149 0 7653 23 1 22 22 0 158 1
amappl16 200 957 0 939 4 0 4 4 0 8 3
amappl15 192 2 0 2 1 0 1 1 0 8 1
amappl14 184 401 0 400 2 1 1 1 0 8 0
amappl13 176 127 0 117 1 0 1 1 0 8 0
amappl12 168 671 0 635 2 0 2 2 0 8 0
amappl11 160 2 0 2 1 0 1 1 0 8 1
amappl10 152 55 0 45 1 0 1 1 0 8 0
amappl9 144 273 0 273 2 1 1 1 0 8 1
amappl8 136 105 0 104 1 0 1 1 0 8 0
amappl7 128 137 0 126 1 0 1 1 0 8 0
amappl6 120 150 0 149 2 1 1 1 0 8 0
amappl5 112 91 0 84 1 0 1 1 0 8 0
amappl4 104 264 0 249 1 0 1 1 0 8 0
amappl3 96 1483 0 1366 5 1 4 4 0 8 0
amappl2 88 524 0 469 3 1 2 2 0 8 0
amappl1 80 10597 0 10022 17 1 16 16 0 8 1
amappl 88 2487 0 2320 5 0 5 5 0 92 0
uvmvnodes 80 97 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 24 439 0 402 1 0 1 1 0 8 0
uaddrbest 32 2 0 0 1 0 1 1 0 8 0
uaddr 24 439 0 402 1 0 1 1 0 8 0
vmmpekpl 168 5620 0 5591 2 0 2 2 0 8 0
vmmpepl 168 37145 0 35134 104 1 103 103 0 357 5
vmsppl 488 438 0 402 7 1 6 6 0 8 0
rwobjpl 80 13742 0 12829 24 1 23 23 0 8 0
pdppl 4096 885 0 804 105 10 95 95 0 8 14
pvpl 32 11001 0 0 90 0 90 90 0 265 1
pmappl 256 438 0 402 4 1 3 3 0 8 0
extentpl 40 45 0 27 1 0 1 1 0 8 0
phpool 112 417 0 13 12 0 12 12 0 8 0
ddb{1}> machine ddbcpu 0
Stopped at x86_ipi_db+0x27: addq $0x8,%rsp
x86_ipi_db(ffffffff8392fff0) 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(ffffffff83a32640) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:142 [inline]
__mp_lock(ffffffff83a32640) at __mp_lock+0x192 sys/kern/kern_lock.c:173
intr_handler(ffff80003c3d6560,ffff8000002a3480) at intr_handler+0xe9 sys/arch/amd64/amd64/intr.c:560
Xintr_ioapic_edge23_untramp() at Xintr_ioapic_edge23_untramp+0x18f
__mp_lock(ffffffff83a32640) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:142 [inline]
__mp_lock(ffffffff83a32640) at __mp_lock+0x192 sys/kern/kern_lock.c:173
sysctl_file(ffff80003c3d6968,4,200000000100,ffff80003c3d6998,ffff8000fffe4d20) at sysctl_file+0x2d20 sys/kern/kern_sysctl.c:1796
kern_sysctl(ffff80003c3d6964,5,200000000100,ffff80003c3d6998,0,37,ac3c8b76fdeba9e5) at kern_sysctl+0x139 sys/kern/kern_sysctl.c:736
sys_sysctl(ffff8000fffe4d20,ffff80003c3d6ad0,ffff80003c3d6a20) at sys_sysctl+0x3e5 sys/kern/kern_sysctl.c:-1
syscall(ffff80003c3d6ad0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003c3d6ad0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x971bd0b2670, count: 3
ddb{0}> trace
x86_ipi_db(ffffffff8392fff0) 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(ffffffff83a32640) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:142 [inline]
__mp_lock(ffffffff83a32640) at __mp_lock+0x192 sys/kern/kern_lock.c:173
intr_handler(ffff80003c3d6560,ffff8000002a3480) at intr_handler+0xe9 sys/arch/amd64/amd64/intr.c:560
Xintr_ioapic_edge23_untramp() at Xintr_ioapic_edge23_untramp+0x18f
__mp_lock(ffffffff83a32640) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:142 [inline]
__mp_lock(ffffffff83a32640) at __mp_lock+0x192 sys/kern/kern_lock.c:173
sysctl_file(ffff80003c3d6968,4,200000000100,ffff80003c3d6998,ffff8000fffe4d20) at sysctl_file+0x2d20 sys/kern/kern_sysctl.c:1796
kern_sysctl(ffff80003c3d6964,5,200000000100,ffff80003c3d6998,0,37,ac3c8b76fdeba9e5) at kern_sysctl+0x139 sys/kern/kern_sysctl.c:736
sys_sysctl(ffff8000fffe4d20,ffff80003c3d6ad0,ffff80003c3d6a20) at sys_sysctl+0x3e5 sys/kern/kern_sysctl.c:-1
syscall(ffff80003c3d6ad0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003c3d6ad0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x971bd0b2670, count: -12
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(ffffffff834bd38e) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff834fa2d3,ffffffff834d4427,4c3,ffffffff8348f102) at __assert+0x29 sys/kern/subr_prf.c:-1
fdfree(ffff8000fffe5a18) at fdfree+0x349
exit1(ffff8000fffe5a18,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215
sys_exit(ffff8000fffe5a18,ffff80003539aa60,ffff80003539a9b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1
syscall(ffff80003539aa60) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003539aa60) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x76a8a0841860, count: 7
ddb{1}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff834bd38e) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff834fa2d3,ffffffff834d4427,4c3,ffffffff8348f102) at __assert+0x29 sys/kern/subr_prf.c:-1
fdfree(ffff8000fffe5a18) at fdfree+0x349
exit1(ffff8000fffe5a18,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215
sys_exit(ffff8000fffe5a18,ffff80003539aa60,ffff80003539a9b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1
syscall(ffff80003539aa60) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003539aa60) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x76a8a0841860, count: -8