panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 953 Stopped at db_enter+0x25: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8333eb70) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337b089,ffffffff833dc7dd,3b9,ffffffff833b6687) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c992080,ffffffff833359ab) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b92,ffff80003c992078) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80002a7f5778) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c9b8c80) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd805e3fa058,41,fffffd8007bfb750,ffff80002a7f5778) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8074a22880,ffff80002a7f5778) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8074a22880,ffff80002a7f5778) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8074a22880,ffff80002a7f5778) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd8074a22880,ffff80002a7f5778) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7f5778) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7f5778,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7f5778,ffff80003c9b8fe0,ffff80003c9b8f30) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff80003c9b8fd0, count: 0 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 *cpu0: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 953 ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8333eb70) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337b089,ffffffff833dc7dd,3b9,ffffffff833b6687) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c992080,ffffffff833359ab) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b92,ffff80003c992078) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80002a7f5778) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c9b8c80) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd805e3fa058,41,fffffd8007bfb750,ffff80002a7f5778) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8074a22880,ffff80002a7f5778) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8074a22880,ffff80002a7f5778) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8074a22880,ffff80002a7f5778) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd8074a22880,ffff80002a7f5778) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7f5778) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7f5778,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7f5778,ffff80003c9b8fe0,ffff80003c9b8f30) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c9b8fe0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c9b8fe0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7ad7ed6206a0, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80003c9b8a60 rbx 0 rdx 0 rcx 0 rax 0xffff80002a7f5778 r8 0x101010101010101 r9 0x8080808080808080 r10 0x31ab62fae68fc1cf r11 0xff7b464491df7bc5 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff83223325 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c9b8a50 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=391748 pid=63075 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002a7f5778 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a7f4550,0xffff80002a7f4d28 process=0xffff8000381544a0 user=0xffff80003c9b4000, vmspace=0xfffffd806ba2f180 estcpu=36, cpticks=1, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 39343 367493 40069 0 2 0 syz-executor 39343 496583 40069 0 3 0x4000080 fsleep syz-executor 39343 250121 40069 0 3 0x4000080 fsleep syz-executor 45209 106141 67766 0 2 0 syz-executor 45209 389253 67766 0 3 0x4000080 fsleep syz-executor 69754 137359 1446 0 2 0 syz-executor 69754 126801 1446 0 3 0x4000000 smrbar syz-executor 69754 518843 1446 0 3 0x4000080 fsleep syz-executor 69754 311789 1446 0 3 0x4000080 fsleep syz-executor 66980 42549 98280 0 3 0 vmmapbsy syz-executor 66980 205801 98280 0 3 0x4000000 vmmapbsy syz-executor 66980 43501 98280 0 3 0x4000080 fsleep syz-executor 66980 221492 98280 0 3 0x4000080 fsleep syz-executor 66980 345855 98280 0 3 0x4000000 fltagain2 syz-executor 44439 42473 93781 0 3 0x82 wait syz-executor 1066 438571 0 0 3 0x14200 acct acct 760 123546 0 0 3 0x14200 bored sosplice 40069 68836 93781 0 2 0xc82 syz-executor 24600 458750 93781 0 3 0x82 wait syz-executor 67766 179414 93781 0 3 0x82 nanoslp syz-executor 1446 400666 93781 0 3 0x82 nanoslp syz-executor 98280 386841 93781 0 3 0x82 nanoslp syz-executor 10903 445220 93781 0 3 0x82 nanoslp syz-executor 9912 296814 93781 0 3 0x82 nanoslp syz-executor 93781 486935 18714 0 3 0x82 kqread syz-executor 18714 514752 76701 0 3 0x10008a sigsusp ksh 76701 14906 70397 0 3 0x98 kqread sshd-session 70397 357239 54753 0 3 0x92 kqread sshd-session 73473 500792 1 0 3 0x100083 ttyopn getty 54753 77945 1 0 3 0x88 kqread sshd 9133 211211 12143 73 3 0x1100090 kqread syslogd 12143 169945 1 0 3 0x100082 sbwait syslogd 38354 315355 1 0 3 0x100080 kqread resolvd 92825 201152 62315 77 3 0x100092 kqread dhcpleased 30881 471015 62315 77 3 0x100092 kqread dhcpleased 62315 163872 1 0 3 0x80 kqread dhcpleased 52064 414885 0 0 3 0x14200 bored smr 35290 50583 0 0 2 0x14200 zerothread 18811 521204 0 0 3 0x14200 aiodoned aiodoned 37263 414677 0 0 3 0x14200 syncer update 52147 33285 0 0 3 0x14200 cleaner cleaner 48556 228511 0 0 3 0x14200 reaper reaper 47698 360173 0 0 3 0x14200 pgdaemon pagedaemon 15601 46642 0 0 3 0x14200 bored viomb 67023 368772 0 0 3 0x40014200 acpi0 acpi0 34241 275252 0 0 3 0x14200 bored softnet7 73538 392228 0 0 3 0x14200 bored softnet6 49764 522125 0 0 3 0x14200 bored softnet5 96413 132882 0 0 3 0x14200 bored softnet4 95944 263670 0 0 3 0x14200 bored softnet3 19180 244949 0 0 3 0x14200 bored softnet2 86120 165880 0 0 3 0x14200 bored softnet1 39436 507788 0 0 3 0x14200 bored softnet0 74178 430659 0 0 3 0x14200 bored systqmp 79447 387985 0 0 3 0x14200 bored systq 14942 253261 0 0 2 0x40014200 softclock 13873 278531 0 0 3 0x40014200 idle0 1 392706 0 0 3 0x82 wait init 0 0 -1 0 3 0x10010200 scheduler swapper ddb> show all locks No such command ddb> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10224 11064K 11459K 166960K 12744 0 pcb 17 16K 21K 166960K 395 0 rtable 210 7K 8K 166960K 387 0 pf 38 14K 15K 166960K 112 0 ifaddr 46 8K 8K 166960K 91 0 ifgroup 66 2K 2K 166960K 141 0 sysctl 4 1K 9K 166960K 74 0 counters 37 18K 18K 166960K 76 0 ioctlops 0 0K 4K 166960K 173 0 iov 0 0K 32K 166960K 184 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1376 87K 87K 166960K 2131 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 3 5K 9K 166960K 14 0 VM map 2 1K 1K 166960K 2 0 sem 12 0K 0K 166960K 95 0 dirhash 12 2K 3K 166960K 27 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 89K 166960K 873 0 sigio 0 0K 0K 166960K 12 0 proc 60 59K 100K 166960K 551 0 subproc 72 4K 4K 166960K 81 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 60 0 in_multi 97 7K 7K 166960K 144 0 ether_multi 1 0K 0K 166960K 8 0 mrt 0 0K 0K 166960K 5 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 223 996K 996K 166960K 223 0 exec 0 0K 1K 166960K 510 0 fusefs mount 1 32K 32K 166960K 1 0 pfkey data 0 0K 0K 166960K 2 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 242 151K 165K 166960K 9121 0 UVM aobj 6 2K 2K 166960K 6 0 pinsyscall 39 78K 92K 166960K 1946 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 26 0 NDP 14 0K 2K 166960K 60 0 temp 78 8644K 8715K 166960K 30221 0 kqueue 14 22K 31K 166960K 165 0 SYN cache 2 16K 16K 166960K 2 0 ddb> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle rtpcb 120 209 0 206 3 1 2 2 0 8 1 rtentry 136 130 0 42 4 0 4 4 0 8 0 unpcb 144 871 0 724 9 3 6 6 0 8 0 syncache 336 6 0 6 2 1 1 1 0 8 1 tcpqe 32 2 0 2 2 1 1 1 0 8 1 tcpcb 736 358 0 349 13 6 7 7 0 8 6 arp 88 15 0 2 1 0 1 1 0 8 0 ipq 40 2 0 0 1 0 1 1 0 8 0 ipqe 40 2 0 0 1 0 1 1 0 8 0 inpcb 328 905 0 891 25 15 10 18 0 8 8 ip6q 72 3 0 2 1 0 1 1 0 8 0 ip6af 40 5 0 4 1 0 1 1 0 8 0 nd6 104 26 0 8 1 0 1 1 0 8 0 pkpcb 40 9 0 9 1 0 1 1 0 8 1 kcovpl 48 9 0 1 1 0 1 1 0 8 0 mppekey 1024 1 0 1 1 1 0 1 0 8 0 ppxss 1072 34 0 32 2 1 1 1 0 8 0 pppxif 1384 6 0 4 2 1 1 1 0 8 0 pfstscr 40 1 0 0 1 0 1 1 0 8 0 pfstitem 24 2 0 0 1 0 1 1 0 8 0 pfstkey 128 2 0 0 1 0 1 1 0 8 0 pfstate 384 1 0 0 1 0 1 1 0 8 0 art_heap8 4096 2 0 0 2 0 2 2 0 8 0 art_heap4 256 634 0 239 29 0 29 29 0 8 2 art_table 40 636 0 239 5 0 5 5 0 8 0 art_node 32 130 0 52 1 0 1 1 0 8 0 sysvmsgpl 40 6 0 4 1 0 1 1 0 8 0 semupl 112 2 0 2 1 0 1 1 0 8 1 semapl 112 92 0 82 1 0 1 1 0 8 0 shmpl 112 3 0 0 1 0 1 1 0 8 0 dirhash 1024 27 0 10 3 0 3 3 0 8 0 dino2pl 256 2946 0 1441 95 0 95 95 0 8 0 ffsino 256 2946 0 1441 95 0 95 95 0 8 0 nchpl 144 4110 0 2419 63 0 63 63 0 8 0 rtmask 32 5 0 5 2 1 1 1 0 8 1 uvmvnodes 80 3493 0 0 72 0 72 72 0 8 0 vnodes 216 3493 0 0 195 0 195 195 0 8 0 namei 1024 13694 0 13694 3 2 1 2 0 8 1 kstatmem 264 84 0 56 3 1 2 3 0 8 0 scsiplug 72 1 0 1 1 1 0 1 0 8 0 scxspl 216 20636 0 20636 15 7 8 8 1 8 8 plimitpl 152 162 0 145 1 0 1 1 0 8 0 sigapl 424 1161 0 1109 7 1 6 7 0 8 0 knotepl 120 31724 0 31675 17 7 10 10 0 8 8 kqueuepl 184 462 0 449 4 0 4 4 0 8 3 pipepl 304 332 0 304 8 0 8 8 0 8 5 fdescpl 448 1138 0 1108 5 1 4 5 0 8 0 filepl 120 7532 0 7169 20 4 16 16 0 8 4 lockfpl 104 412 0 409 1 0 1 1 0 8 0 lockfspl 48 183 0 180 1 0 1 1 0 8 0 sessionpl 144 25 0 17 1 0 1 1 0 8 0 pgrppl 48 37 0 21 1 0 1 1 0 8 0 ucredpl 104 1197 0 1185 1 0 1 1 0 8 0 zombiepl 144 1113 0 1109 1 0 1 1 0 8 0 processpl 1152 1161 0 1109 5 1 4 5 0 8 0 procpl 664 2258 0 2196 7 0 7 7 0 8 1 sosppl 168 1 0 1 1 0 1 1 0 8 1 sockpl 552 2114 0 1950 29 17 12 19 0 8 0 mcl64k 65536 32 0 32 2 1 1 1 0 8 1 mcl16k 16384 2 0 2 1 0 1 1 0 8 1 mcl12k 12288 33 0 33 1 0 1 1 0 8 1 mcl8k 8192 13 0 12 2 1 1 1 0 8 0 mcl4k 4096 3539 0 3488 14 6 8 13 0 8 1 mcl2k2 2112 7 0 7 2 1 1 1 0 8 1 mcl2k 2048 1268 0 1263 3 1 2 2 0 8 1 mtagpl 96 16 0 9 2 1 1 1 0 8 0 mbufpl 256 12175 0 12014 14 0 14 14 0 8 1 bufpl 280 10755 0 4527 445 0 445 445 0 8 0 anonpl 24 210298 0 204801 73 1 72 72 0 187 35 amapchunkpl 152 31012 0 30487 30 0 30 30 0 158 9 amappl16 200 4353 0 4177 58 28 30 30 0 8 19 amappl15 192 2 0 2 1 1 0 1 0 8 0 amappl14 184 109 0 99 1 0 1 1 0 8 0 amappl13 176 7 0 7 1 1 0 1 0 8 0 amappl12 168 1768 0 1738 3 1 2 3 0 8 0 amappl11 160 47 0 36 1 0 1 1 0 8 0 amappl10 152 4 0 4 1 1 0 1 0 8 0 amappl9 144 268 0 268 1 1 0 1 0 8 0 amappl8 136 18 0 17 1 0 1 1 0 8 0 amappl7 128 103 0 93 1 0 1 1 0 8 0 amappl6 120 186 0 183 1 0 1 1 0 8 0 amappl5 112 117 0 110 1 0 1 1 0 8 0 amappl4 104 311 0 295 1 0 1 1 0 8 0 amappl3 96 5954 0 5834 4 0 4 4 0 8 1 amappl2 88 669 0 612 2 0 2 2 0 8 0 amappl1 80 11755 0 11204 14 0 14 14 0 8 0 amappl 88 8301 0 8126 5 0 5 5 0 92 0 dma4096 4096 1 0 1 1 1 0 1 0 8 0 dma2048 2048 1 0 1 1 0 1 1 0 8 1 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 128 254 0 254 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 19 0 18 1 0 1 1 0 8 0 aobjpl 72 5 0 0 1 0 1 1 0 8 0 uaddrrnd 24 1138 0 1108 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 1138 0 1108 1 0 1 1 0 8 0 vmmpekpl 168 10260 0 10222 2 0 2 2 0 8 0 vmmpepl 168 77687 0 75612 109 2 107 107 0 357 16 vmsppl 368 1137 0 1108 4 1 3 4 0 8 0 rwobjpl 40 25752 0 21237 50 0 50 50 0 8 1 pdppl 4096 2282 0 2216 100 34 66 78 0 8 0 pvpl 32 533929 0 522938 150 1 149 149 0 265 52 pmappl 216 1137 0 1108 2 0 2 2 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 392 0 57 10 0 10 10 0 8 0 ddb> machine ddbcpu 0 No such command ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8333eb70) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337b089,ffffffff833dc7dd,3b9,ffffffff833b6687) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c992080,ffffffff833359ab) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b92,ffff80003c992078) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80002a7f5778) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c9b8c80) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd805e3fa058,41,fffffd8007bfb750,ffff80002a7f5778) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8074a22880,ffff80002a7f5778) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8074a22880,ffff80002a7f5778) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8074a22880,ffff80002a7f5778) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd8074a22880,ffff80002a7f5778) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7f5778) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7f5778,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7f5778,ffff80003c9b8fe0,ffff80003c9b8f30) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c9b8fe0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c9b8fe0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7ad7ed6206a0, count: -16 ddb> machine ddbcpu 1 No such command ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8333eb70) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337b089,ffffffff833dc7dd,3b9,ffffffff833b6687) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c992080,ffffffff833359ab) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b92,ffff80003c992078) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80002a7f5778) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c9b8c80) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd805e3fa058,41,fffffd8007bfb750,ffff80002a7f5778) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8074a22880,ffff80002a7f5778) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8074a22880,ffff80002a7f5778) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8074a22880,ffff80002a7f5778) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd8074a22880,ffff80002a7f5778) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7f5778) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7f5778,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7f5778,ffff80003c9b8fe0,ffff80003c9b8f30) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c9b8fe0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c9b8fe0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7ad7ed6206a0, count: -16