panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 944 Stopped at db_enter+0x25: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 299196 45346 0 0 0 1 syz-executor db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff8343d9f2) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e5449,ffffffff833eba8a,3b0,ffffffff833ebad2) at __assert+0x29 refcnt_finalize(ffff8000334cb990,ffffffff8332f94c) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff8000334cb988) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff80002a374028) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff8000380d2330) at spec_close+0x412 VOP_CLOSE(fffffd806ba68b28,1,fffffd807f7d2548,ffff80002a374028) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806bd7d1e8,ffff80002a374028) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806bd7d1e8,ffff80002a374028) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806bd7d1e8,ffff80002a374028) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd806bd7d1e8,ffff80002a374028) at closef+0x192 sys/kern/kern_descrip.c:1249 fdfree(ffff80002a374028) at fdfree+0x116 sys/kern/kern_descrip.c:1181 exit1(ffff80002a374028,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff80002a374028,ffff8000380d26a0,ffff8000380d25f0) at sys_exit+0x1a end trace frame: 0xffff8000380d2690, 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{0}> ddb{0}> set $lines = 0 ddb{0}> set $maxwidth = 0 ddb{0}> show panic *cpu0: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 944 ddb{0}> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff8343d9f2) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e5449,ffffffff833eba8a,3b0,ffffffff833ebad2) at __assert+0x29 refcnt_finalize(ffff8000334cb990,ffffffff8332f94c) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff8000334cb988) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff80002a374028) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff8000380d2330) at spec_close+0x412 VOP_CLOSE(fffffd806ba68b28,1,fffffd807f7d2548,ffff80002a374028) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806bd7d1e8,ffff80002a374028) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806bd7d1e8,ffff80002a374028) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806bd7d1e8,ffff80002a374028) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd806bd7d1e8,ffff80002a374028) at closef+0x192 sys/kern/kern_descrip.c:1249 fdfree(ffff80002a374028) at fdfree+0x116 sys/kern/kern_descrip.c:1181 exit1(ffff80002a374028,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff80002a374028,ffff8000380d26a0,ffff8000380d25f0) at sys_exit+0x1a syscall(ffff8000380d26a0) at syscall+0xb08 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff8000380d26a0) at syscall+0xb08 sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x748e87e7e7a0, count: -16 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff8000380d2100 rbx 0xffffffff837e4dc7 cpu_info_full_primary+0x2dc7 rdx 0 rcx 0xffff80002a374028 rax 0xffffffff837e3ff0 cpu_info_full_primary+0x1ff0 r8 0 r9 0x8080808080808080 r10 0x2e102ffd87978a40 r11 0x17542d83db266378 r12 0xffffffff837e4bc8 cpu_info_full_primary+0x2bc8 r13 0 r14 0 r15 0x1 rip 0xffffffff8162a2e5 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff8000380d20f0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor) tid=484959 pid=63516 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002a374028 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a375468,0xffff80002a368f60 process=0xffff8000398d5010 user=0xffff8000380cd000, vmspace=0xfffffd806321e580 estcpu=36, cpticks=3, pctcpu=0.0, user=0, sys=1, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 96112 464022 26115 0 2 0 syz-executor 96112 148185 26115 0 3 0x4000000 smrbar syz-executor 45346 299196 40393 0 7 0 syz-executor 45346 201185 40393 0 2 0x4000080 syz-executor 69059 316588 79352 0 2 0 syz-executor 69059 357828 79352 0 3 0x4000080 piperd syz-executor 34997 100214 63720 0 3 0x80 nanoslp syz-executor 34997 178341 63720 0 3 0x4000080 fsleep syz-executor 34997 41165 63720 0 3 0x4000080 fsleep syz-executor 55021 405751 20797 0 3 0x80 nanoslp syz-executor 55021 108582 20797 0 3 0x4000080 kqread syz-executor 55021 331187 20797 0 3 0x4000080 fsleep syz-executor 4531 88537 73706 0 3 0x80 nanoslp syz-executor 4531 20375 73706 0 3 0x4000080 fifor syz-executor 4531 389719 73706 0 3 0x4000080 kqread syz-executor 55974 261897 0 0 3 0x14200 bored sosplice 63720 2440 51132 0 3 0x82 nanoslp syz-executor 20797 519910 51132 0 2 0x482 syz-executor 26115 198285 51132 0 3 0x82 nanoslp syz-executor 40393 69072 51132 0 2 0x482 syz-executor 70031 212702 51132 0 3 0x82 nanoslp syz-executor 79352 434627 51132 0 2 0x2 syz-executor 73706 9501 51132 0 2 0x482 syz-executor 80138 475295 51132 0 2 0x2 syz-executor 51132 49939 49501 0 3 0x82 kqread syz-executor 49501 183269 65273 0 3 0x10008a sigsusp ksh 65273 361297 85345 0 3 0x98 kqread sshd-session 85345 399011 55038 0 3 0x92 kqread sshd-session 90696 307498 1 0 3 0x100083 ttyopn getty 55038 267978 1 0 3 0x88 kqread sshd 88966 486659 10888 74 3 0x1100092 bpf pflogd 10888 313640 1 0 3 0x80 sbwait pflogd 18649 170263 21150 73 3 0x1100090 kqread syslogd 21150 220413 1 0 3 0x100082 sbwait syslogd 14838 514797 1 0 3 0x100080 kqread resolvd 57825 161005 58483 77 3 0x100092 kqread dhcpleased 29377 210468 58483 77 3 0x100092 kqread dhcpleased 58483 425965 1 0 3 0x80 kqread dhcpleased 86546 274221 0 0 3 0x14200 bored smr 39802 193495 0 0 2 0x14200 zerothread 99281 73132 0 0 3 0x14200 aiodoned aiodoned 26623 100894 0 0 3 0x14200 syncer update 71269 238173 0 0 3 0x14200 cleaner cleaner 95470 204043 0 0 3 0x14200 reaper reaper 59409 327237 0 0 3 0x14200 pgdaemon pagedaemon 29705 219547 0 0 3 0x14200 bored viomb 68201 136296 0 0 3 0x40014200 acpi0 acpi0 7657 403468 0 0 3 0x40014200 idle1 36270 347954 0 0 3 0x14200 bored softnet3 1087 460609 0 0 3 0x14200 bored softnet2 41715 506297 0 0 3 0x14200 bored softnet1 22577 460502 0 0 3 0x14200 bored softnet0 23767 338087 0 0 3 0x14200 bored systqmp 18709 321892 0 0 3 0x14200 bored systq 94390 217167 0 0 3 0x14200 tmoslp softclockmp 49344 312474 0 0 2 0x40014200 softclock 87266 285145 0 0 3 0x40014200 idle0 1 355025 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{0}> show all locks Process 45346 (syz-executor) thread 0xffff80002a368f50 (299196) exclusive rwlock vmmaplk r = 0 (0xfffffd806321eda0) #0 witness_lock+0x5bb stacktrace_save sys/sys/stacktrace.h:37 [inline] #0 witness_lock+0x5bb sys/kern/subr_witness.c:1155 #1 rw_do_enter_write+0x3ea sys/kern/kern_rwlock.c:316 #2 vm_map_lock_ln+0x12e sys/uvm/uvm_map.c:5250 #3 uvm_map_protect+0xe1 sys/uvm/uvm_map.c:3057 #4 sys_mprotect+0x34c sys/uvm/uvm_mmap.c:590 #5 syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] #5 syscall+0xbc6 sys/arch/amd64/amd64/trap.c:577 #6 Xsyscall+0x128 ddb{0}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10202 11028K 11351K 166960K 11820 0 pcb 20 12K 12K 166960K 83 0 rtable 248 11K 12K 166960K 401 0 pf 38 18K 19K 166960K 128 0 ifaddr 45 8K 8K 166960K 58 0 ifgroup 60 2K 2K 166960K 79 0 sysctl 3 1K 1K 166960K 3 0 counters 68 36K 37K 166960K 80 0 ioctlops 0 0K 4K 166960K 1593 0 iov 1 12K 16K 166960K 21 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1335 84K 84K 166960K 1674 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 14 0 dirhash 12 2K 2K 166960K 18 0 ACPI 1690 195K 286K 166960K 12468 0 file desc 17 61K 97K 166960K 468 0 sigio 0 0K 0K 166960K 9 0 proc 73 103K 128K 166960K 553 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 2 0K 0K 166960K 54 0 in_multi 100 7K 7K 166960K 124 0 ether_multi 1 0K 0K 166960K 2 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 85 387K 387K 166960K 85 0 exec 0 0K 1K 166960K 464 0 fusefs mount 1 32K 32K 166960K 1 0 pfkey data 0 0K 0K 166960K 1 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 220 72K 73K 166960K 5900 0 UVM aobj 23 2K 2K 166960K 23 0 pinsyscall 42 84K 105K 166960K 1551 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 18 0 NDP 13 0K 2K 166960K 36 0 temp 54 8638K 8704K 166960K 13739 0 kqueue 15 24K 28K 166960K 73 0 SYN cache 2 16K 16K 166960K 2 0 ddb{0}> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle plcache 128 24 0 0 1 0 1 1 0 8 0 rtpcb 120 58 0 54 1 0 1 1 0 8 0 rtentry 112 120 0 7 4 0 4 4 0 8 0 unpcb 144 231 0 210 2 0 2 2 0 8 1 syncache 336 4 0 4 2 1 1 1 0 8 1 tcpcb 808 145 0 139 7 2 5 7 0 8 4 arp 120 19 0 0 1 0 1 1 0 8 0 inpcb 376 419 0 404 8 2 6 8 0 8 4 nd6 136 25 0 0 1 0 1 1 0 8 0 pkpcb 40 1 0 0 1 0 1 1 0 8 0 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1168 4 0 3 2 1 1 1 0 8 0 pppxif 1472 2 0 1 2 1 1 1 0 8 0 pffrag 232 2 0 1 1 0 1 1 0 482 0 pffrnode 88 2 0 1 1 0 1 1 0 8 0 pffrent 40 3 0 2 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 41 0 1 1 0 1 1 0 8 0 pfstkey 128 43 0 3 2 0 2 2 0 8 0 pfstate 376 41 0 2 4 0 4 4 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 256 524 0 64 32 1 31 31 0 8 2 art_table 32 525 0 64 4 0 4 4 0 8 0 art_node 16 117 0 15 1 0 1 1 0 8 0 sysvmsgpl 40 8 0 6 1 0 1 1 0 8 0 semupl 112 1 0 1 1 0 1 1 0 8 1 semapl 112 12 0 2 1 0 1 1 0 8 0 shmpl 112 20 0 0 1 0 1 1 0 8 0 dirhash 1024 21 0 4 3 0 3 3 0 8 0 dino2pl 256 2268 0 763 95 0 95 95 0 8 0 ffsino 280 2268 0 763 109 0 109 109 0 8 0 nchpl 144 2945 0 1252 63 0 63 63 0 8 0 uvmvnodes 80 2460 0 0 51 0 51 51 0 8 0 vnodes 216 2460 0 0 137 0 137 137 0 8 0 namei 1024 9516 0 9516 1 0 1 1 0 8 1 percpumem 16 54 0 6 1 0 1 1 0 8 0 kstatmem 264 36 0 10 2 0 2 2 0 8 0 scsiplug 72 1 0 1 1 0 1 1 0 8 1 scxspl 216 8624 0 8624 3 2 1 2 1 8 1 plimitpl 152 98 0 80 1 0 1 1 0 8 0 sigapl 424 768 0 718 7 1 6 7 0 8 0 futexpl 64 5362 0 5359 1 0 1 1 0 8 0 knotepl 120 544 0 0 17 0 17 17 0 8 0 kqueuepl 216 106 0 93 1 0 1 1 0 8 0 pipepl 328 139 0 111 3 0 3 3 0 8 0 fdescpl 504 749 0 718 6 1 5 6 0 8 0 filepl 152 4119 0 3881 12 0 12 12 0 8 0 lockfpl 104 148 0 145 1 0 1 1 0 8 0 lockfspl 48 56 0 53 1 0 1 1 0 8 0 sessionpl 144 23 0 14 1 0 1 1 0 8 0 pgrppl 48 38 0 21 1 0 1 1 0 8 0 ucredpl 104 792 0 779 1 0 1 1 0 8 0 zombiepl 144 719 0 718 1 0 1 1 0 8 0 processpl 1168 768 0 718 5 1 4 5 0 8 0 procpl 648 1347 0 1288 6 0 6 6 0 8 0 sosppl 168 4 0 4 1 0 1 1 0 8 1 sockpl 688 714 0 672 10 2 8 10 0 8 3 mcl64k 65536 2 0 0 1 0 1 1 0 8 0 mcl12k 12288 1 0 0 1 0 1 1 0 8 0 mcl9k 9216 1 0 0 1 0 1 1 0 8 0 mcl8k 8192 5 0 0 1 0 1 1 0 8 0 mcl4k 4096 122 0 0 16 0 16 16 0 8 0 mcl2k 2048 18 0 0 3 0 3 3 0 8 0 mtagpl 96 46 0 0 2 0 2 2 0 8 0 mbufpl 256 186 0 0 12 0 12 12 0 8 0 bufpl 280 2866 0 130 196 0 196 196 0 8 0 anonpl 24 100844 0 97371 46 0 46 46 0 184 18 amapchunkpl 152 17707 0 17243 24 0 24 24 0 158 3 amappl16 200 1461 0 1428 19 8 11 15 0 8 8 amappl15 192 3 0 3 1 1 0 1 0 8 0 amappl14 184 109 0 97 1 0 1 1 0 8 0 amappl13 176 3 0 3 2 1 1 1 0 8 1 amappl12 168 1385 0 1354 4 1 3 3 0 8 0 amappl11 160 67 0 53 1 0 1 1 0 8 0 amappl10 152 15 0 15 1 1 0 1 0 8 0 amappl9 144 254 0 254 1 1 0 1 0 8 0 amappl8 136 20 0 17 1 0 1 1 0 8 0 amappl7 128 130 0 117 1 0 1 1 0 8 0 amappl6 120 219 0 216 1 0 1 1 0 8 0 amappl5 112 123 0 113 1 0 1 1 0 8 0 amappl4 104 326 0 305 1 0 1 1 0 8 0 amappl3 96 3523 0 3417 5 1 4 4 0 8 0 amappl2 88 638 0 574 2 0 2 2 0 8 0 amappl1 80 8923 0 8343 15 1 14 15 0 8 1 amappl 88 5508 0 5345 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 7 0 7 2 1 1 1 0 8 1 dma128 128 254 0 254 2 1 1 1 0 8 1 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 22 0 0 1 0 1 1 0 8 0 uaddrrnd 24 749 0 718 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 749 0 718 1 0 1 1 0 8 0 vmmpekpl 168 7587 0 7543 3 0 3 3 0 8 0 vmmpepl 168 50900 0 49025 94 0 94 94 0 357 9 vmsppl 456 748 0 718 6 1 5 5 0 8 1 rwobjpl 64 17966 0 14560 56 0 56 56 0 8 0 pdppl 4096 1506 0 1436 104 32 72 88 0 8 2 pvpl 32 14590 0 0 120 2 118 118 0 265 0 pmappl 248 748 0 718 3 0 3 3 0 8 0 extentpl 40 55 0 38 1 0 1 1 0 8 0 phpool 112 296 0 41 8 0 8 8 0 8 0 ddb{0}> machine ddbcpu 0 Invalid cpu 0 ddb{0}> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff8343d9f2) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e5449,ffffffff833eba8a,3b0,ffffffff833ebad2) at __assert+0x29 refcnt_finalize(ffff8000334cb990,ffffffff8332f94c) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff8000334cb988) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff80002a374028) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff8000380d2330) at spec_close+0x412 VOP_CLOSE(fffffd806ba68b28,1,fffffd807f7d2548,ffff80002a374028) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806bd7d1e8,ffff80002a374028) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806bd7d1e8,ffff80002a374028) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806bd7d1e8,ffff80002a374028) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd806bd7d1e8,ffff80002a374028) at closef+0x192 sys/kern/kern_descrip.c:1249 fdfree(ffff80002a374028) at fdfree+0x116 sys/kern/kern_descrip.c:1181 exit1(ffff80002a374028,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff80002a374028,ffff8000380d26a0,ffff8000380d25f0) at sys_exit+0x1a syscall(ffff8000380d26a0) at syscall+0xb08 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff8000380d26a0) at syscall+0xb08 sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x748e87e7e7a0, count: -16 ddb{0}> machine ddbcpu 1 Stopped at x86_ipi_db+0x27: addq $0x8,%rsp x86_ipi_db(ffff800029aabff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:393 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 end of kernel end trace frame: 0x734e0a3123c0, count: 12 ddb{1}> trace x86_ipi_db(ffff800029aabff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:393 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 end of kernel end trace frame: 0x734e0a3123c0, count: -3