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 495835 11035 0 0 0 1 syz-executor db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff8343b582) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e7d34,ffffffff833f04dc,3b0,ffffffff833f0524) at __assert+0x29 refcnt_finalize(ffff80003b0d2e08,ffffffff8332fc97) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003b0d2e00) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff80003b0cecd8) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c518380) at spec_close+0x412 VOP_CLOSE(fffffd805d477b38,1,fffffd807f7d3680,ffff80003b0cecd8) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806be32278,ffff80003b0cecd8) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806be32278,ffff80003b0cecd8) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806be32278,ffff80003b0cecd8) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd806be32278,ffff80003b0cecd8) at closef+0x192 sys/kern/kern_descrip.c:1249 fdfree(ffff80003b0cecd8) at fdfree+0x116 sys/kern/kern_descrip.c:1181 exit1(ffff80003b0cecd8,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff80003b0cecd8,ffff80003c5186f0,ffff80003c518640) at sys_exit+0x1a end trace frame: 0xffff80003c5186e0, 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(ffffffff8343b582) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e7d34,ffffffff833f04dc,3b0,ffffffff833f0524) at __assert+0x29 refcnt_finalize(ffff80003b0d2e08,ffffffff8332fc97) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003b0d2e00) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff80003b0cecd8) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c518380) at spec_close+0x412 VOP_CLOSE(fffffd805d477b38,1,fffffd807f7d3680,ffff80003b0cecd8) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806be32278,ffff80003b0cecd8) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806be32278,ffff80003b0cecd8) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806be32278,ffff80003b0cecd8) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd806be32278,ffff80003b0cecd8) at closef+0x192 sys/kern/kern_descrip.c:1249 fdfree(ffff80003b0cecd8) at fdfree+0x116 sys/kern/kern_descrip.c:1181 exit1(ffff80003b0cecd8,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff80003b0cecd8,ffff80003c5186f0,ffff80003c518640) at sys_exit+0x1a syscall(ffff80003c5186f0) at syscall+0xb08 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c5186f0) at syscall+0xb08 sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72951e6eccc0, count: -16 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff80003c518150 rbx 0xffffffff83884dc7 cpu_info_full_primary+0x2dc7 rdx 0 rcx 0xffff80003b0cecd8 rax 0xffffffff83883ff0 cpu_info_full_primary+0x1ff0 r8 0 r9 0x8080808080808080 r10 0xb9107ea21c1f764 r11 0x1f4d0917c7d84fa1 r12 0xffffffff83884bc8 cpu_info_full_primary+0x2bc8 r13 0 r14 0 r15 0x1 rip 0xffffffff811241e5 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c518140 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor) tid=254586 pid=7036 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=77, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80003b0cecd8 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80003b0cf470,0xffff8000ffff9470 process=0xffff80002f8a6b78 user=0xffff80003c513000, vmspace=0xfffffd8068f13578 estcpu=27, cpticks=5, pctcpu=0.0, user=0, sys=2, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 98164 34566 9667 0 2 0x480 syz-executor 98164 284894 9667 0 3 0x4000080 fsleep syz-executor 98164 510789 9667 0 2 0x4000000 syz-executor 98164 384232 9667 0 3 0x4000080 fsleep syz-executor 21109 19846 68881 0 2 0 syz-executor 21109 419509 68881 0 3 0x4000080 fsleep syz-executor 11035 495835 45030 0 7 0 syz-executor 11035 279711 45030 0 3 0x4000000 smrbar syz-executor 55786 373233 53390 0 2 0 syz-executor 55786 267185 53390 0 3 0x4000080 fsleep syz-executor 55786 349418 53390 0 2 0x4000000 syz-executor 41296 134400 7216 0 2 0 syz-executor 41296 257208 7216 0 3 0x4000080 kqsel syz-executor 78323 313291 27366 0 2 0 syz-executor 78323 455132 27366 0 3 0x4000080 kqread syz-executor 78323 116308 27366 0 3 0x4000080 fsleep syz-executor 75670 224634 23963 0 2 0x480 syz-executor 75670 234932 23963 0 3 0x4000080 ttyin syz-executor 43039 327398 0 0 3 0x14200 bored sosplice 37403 16383 96699 0 3 0x82 nanoslp syz-executor 68881 237483 96699 0 2 0x482 syz-executor 53390 483669 96699 0 2 0x2 syz-executor 27366 227190 96699 0 3 0x82 nanoslp syz-executor 9667 361010 96699 0 2 0x482 syz-executor 23963 120503 96699 0 3 0x82 nanoslp syz-executor 7216 179642 96699 0 2 0x2 syz-executor 45030 270335 96699 0 2 0x482 syz-executor 96699 76859 12444 0 3 0x82 kqread syz-executor 12444 431466 8354 0 3 0x10008a sigsusp ksh 8354 169029 60461 0 3 0x98 kqread sshd-session 60461 55124 11533 0 3 0x92 kqread sshd-session 35794 370882 1 0 3 0x100083 ttyin getty 11533 54502 1 0 3 0x88 kqread sshd 30806 2478 65855 74 3 0x1100092 bpf pflogd 65855 469077 1 0 3 0x80 sbwait pflogd 96467 330225 49456 73 3 0x1100090 kqread syslogd 49456 216552 1 0 3 0x100082 sbwait syslogd 11918 1680 1 0 3 0x100080 kqread resolvd 43533 154669 91406 77 3 0x100092 kqread dhcpleased 99666 231964 91406 77 3 0x100092 kqread dhcpleased 91406 143405 1 0 3 0x80 kqread dhcpleased 82491 161405 0 0 3 0x14200 pause smr 54512 110780 0 0 2 0x14200 zerothread 68747 129830 0 0 3 0x14200 aiodoned aiodoned 730 297294 0 0 3 0x14200 syncer update 4696 24762 0 0 3 0x14200 cleaner cleaner 34499 411901 0 0 3 0x14200 reaper reaper 32068 429256 0 0 3 0x14200 pgdaemon pagedaemon 25600 21769 0 0 3 0x14200 bored viomb 42769 359368 0 0 3 0x40014200 acpi0 acpi0 28036 446931 0 0 3 0x40014200 idle1 1839 471373 0 0 3 0x14200 bored softnet3 82647 309427 0 0 3 0x14200 bored softnet2 46077 367778 0 0 3 0x14200 bored softnet1 61568 316457 0 0 3 0x14200 bored softnet0 24283 13271 0 0 3 0x14200 bored systqmp 38591 324797 0 0 3 0x14200 bored systq 71397 163941 0 0 3 0x14200 tmoslp softclockmp 66373 486819 0 0 3 0x40014200 tmoslp softclock 19221 25679 0 0 3 0x40014200 idle0 1 15758 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{0}> show all locks Process 75670 (syz-executor) thread 0xffff80003b0d7988 (234932) exclusive rrwlock inode r = 0 (0xfffffd8068c11500) #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 rrw_enter+0xc6 sys/kern/kern_rwlock.c:616 #3 VOP_LOCK+0xa6 sys/kern/vfs_vops.c:524 #4 vn_lock+0xa4 sys/kern/vfs_vnops.c:570 #5 spec_open+0x305 sys/kern/spec_vnops.c:151 #6 VOP_OPEN+0x8b sys/kern/vfs_vops.c:138 #7 vn_open+0x708 sys/kern/vfs_vnops.c:177 #8 vndioctl+0xcb1 sys/dev/vnd.c:457 #9 VOP_IOCTL+0xac sys/kern/vfs_vops.c:264 #10 vn_ioctl+0xf8 sys/kern/vfs_vnops.c:531 #11 sys_ioctl+0x5c3 #12 syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] #12 syscall+0xbc6 sys/arch/amd64/amd64/trap.c:577 #13 Xsyscall+0x128 ddb{0}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10203 11149K 11417K 166960K 11526 0 pcb 18 14K 16K 166960K 128 0 rtable 221 7K 7K 166960K 409 0 pf 35 17K 18K 166960K 55 0 ifaddr 42 7K 7K 166960K 53 0 ifgroup 56 2K 2K 166960K 69 0 sysctl 3 1K 1K 166960K 3 0 counters 66 36K 36K 166960K 74 0 ioctlops 0 0K 4K 166960K 1500 0 iov 0 0K 16K 166960K 7 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1378 87K 87K 166960K 1568 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 5K 166960K 4 0 VM map 2 1K 1K 166960K 2 0 sem 6 0K 0K 166960K 8 0 dirhash 12 2K 2K 166960K 12 0 ACPI 1690 195K 286K 166960K 12468 0 file desc 18 65K 89K 166960K 285 0 sigio 0 0K 0K 166960K 3 0 proc 72 91K 128K 166960K 554 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 4 0K 0K 166960K 24 0 in_multi 93 6K 7K 166960K 108 0 ether_multi 1 0K 0K 166960K 1 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 73 334K 334K 166960K 73 0 exec 0 0K 1K 166960K 394 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 232 73K 73K 166960K 4228 0 UVM aobj 10 2K 2K 166960K 10 0 pinsyscall 43 86K 104K 166960K 1363 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 6 0 NDP 12 0K 2K 166960K 33 0 temp 42 8635K 8702K 166960K 6768 0 kqueue 16 26K 30K 166960K 63 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 42 0 39 1 0 1 1 0 8 0 rtentry 112 117 0 16 4 0 4 4 0 8 0 unpcb 144 103 0 83 2 0 2 2 0 8 0 syncache 336 3 0 3 1 0 1 1 0 8 1 tcpcb 808 41 0 37 1 0 1 1 0 8 0 arp 120 19 0 3 1 0 1 1 0 8 0 inpcb 376 256 0 246 8 0 8 8 0 8 7 nd6 136 25 0 3 1 0 1 1 0 8 0 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1168 3 0 2 1 0 1 1 0 8 0 pppxif 1472 1 0 0 1 0 1 1 0 8 0 pffrag 232 1 0 0 1 0 1 1 0 482 0 pffrnode 88 1 0 0 1 0 1 1 0 8 0 pffrent 40 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 31 0 0 1 0 1 1 0 8 0 pfstkey 128 31 0 0 1 0 1 1 0 8 0 pfstate 376 31 0 0 4 0 4 4 0 8 0 pfrule 1344 24 0 17 2 1 1 2 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 517 0 46 30 0 30 30 0 8 0 art_table 32 518 0 46 4 0 4 4 0 8 0 art_node 16 115 0 24 1 0 1 1 0 8 0 sysvmsgpl 40 1 0 1 1 0 1 1 0 8 1 semapl 112 5 0 1 1 0 1 1 0 8 0 shmpl 112 7 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1900 0 391 95 0 95 95 0 8 0 ffsino 280 1900 0 391 109 0 109 109 0 8 0 nchpl 144 2304 0 612 63 0 63 63 0 8 0 uvmvnodes 80 2091 0 0 43 0 43 43 0 8 0 vnodes 216 2091 0 0 117 0 117 117 0 8 0 namei 1024 7394 0 7394 2 0 2 2 0 8 2 percpumem 16 51 0 4 1 0 1 1 0 8 0 kstatmem 264 32 0 8 2 0 2 2 0 8 0 scsiplug 72 1 0 1 1 0 1 1 0 8 1 scxspl 216 7143 0 7143 4 1 3 3 1 8 3 plimitpl 152 43 0 25 1 0 1 1 0 8 0 sigapl 424 584 0 533 8 1 7 7 0 8 1 futexpl 64 2403 0 2398 1 0 1 1 0 8 0 knotepl 120 327 0 0 10 0 10 10 0 8 0 kqueuepl 216 105 0 89 3 0 3 3 0 8 2 pipepl 328 120 0 93 3 0 3 3 0 8 0 fdescpl 504 565 0 533 5 0 5 5 0 8 0 filepl 152 2716 0 2488 16 0 16 16 0 8 6 lockfpl 104 77 0 74 1 0 1 1 0 8 0 lockfspl 48 35 0 32 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 104 414 0 400 1 0 1 1 0 8 0 zombiepl 144 534 0 533 1 0 1 1 0 8 0 processpl 1168 584 0 533 5 0 5 5 0 8 1 procpl 648 863 0 801 8 1 7 7 0 8 1 srpgc 96 2 0 2 1 0 1 1 0 8 1 sockpl 688 404 0 371 9 0 9 9 0 8 5 mcl64k 65536 1 0 0 1 0 1 1 0 8 0 mcl8k 8192 4 0 0 1 0 1 1 0 8 0 mcl4k 4096 113 0 0 15 0 15 15 0 8 0 mcl2k 2048 18 0 0 3 0 3 3 0 8 0 mtagpl 96 6 0 0 1 0 1 1 0 8 0 mbufpl 256 222 0 0 14 0 14 14 0 8 0 bufpl 280 2688 0 132 183 0 183 183 0 8 0 anonpl 24 116532 0 113133 47 1 46 46 0 184 22 amapchunkpl 152 13097 0 12587 24 0 24 24 0 158 2 amappl16 200 2333 0 2302 11 1 10 11 0 8 7 amappl15 192 17 0 17 2 2 0 1 0 8 0 amappl14 184 148 0 136 1 0 1 1 0 8 0 amappl13 176 7 0 7 2 2 0 1 0 8 0 amappl12 168 1203 0 1170 3 1 2 2 0 8 0 amappl11 160 50 0 35 1 0 1 1 0 8 0 amappl10 152 4 0 4 1 1 0 1 0 8 0 amappl9 144 250 0 249 1 0 1 1 0 8 0 amappl8 136 63 0 61 1 0 1 1 0 8 0 amappl7 128 107 0 95 1 0 1 1 0 8 0 amappl6 120 179 0 176 1 0 1 1 0 8 0 amappl5 112 117 0 108 1 0 1 1 0 8 0 amappl4 104 309 0 289 1 0 1 1 0 8 0 amappl3 96 2307 0 2188 5 1 4 5 0 8 0 amappl2 88 635 0 574 2 0 2 2 0 8 0 amappl1 80 8124 0 7547 14 0 14 14 0 8 1 amappl 88 3849 0 3674 5 0 5 5 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 128 255 0 255 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 18 0 17 1 0 1 1 0 8 0 aobjpl 72 9 0 0 1 0 1 1 0 8 0 uaddrrnd 24 565 0 533 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 565 0 533 1 0 1 1 0 8 0 vmmpekpl 168 6291 0 6261 2 0 2 2 0 8 0 vmmpepl 168 41065 0 39146 91 0 91 91 0 357 5 vmsppl 456 564 0 533 5 0 5 5 0 8 1 rwobjpl 64 16507 0 13470 50 0 50 50 0 8 0 pdppl 4096 1137 0 1066 93 22 71 83 0 8 0 pvpl 32 13806 0 0 112 0 112 112 0 265 0 pmappl 248 564 0 533 3 0 3 3 0 8 0 extentpl 40 55 0 38 1 0 1 1 0 8 0 phpool 112 274 0 24 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(ffffffff8343b582) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e7d34,ffffffff833f04dc,3b0,ffffffff833f0524) at __assert+0x29 refcnt_finalize(ffff80003b0d2e08,ffffffff8332fc97) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003b0d2e00) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff80003b0cecd8) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c518380) at spec_close+0x412 VOP_CLOSE(fffffd805d477b38,1,fffffd807f7d3680,ffff80003b0cecd8) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806be32278,ffff80003b0cecd8) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806be32278,ffff80003b0cecd8) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806be32278,ffff80003b0cecd8) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd806be32278,ffff80003b0cecd8) at closef+0x192 sys/kern/kern_descrip.c:1249 fdfree(ffff80003b0cecd8) at fdfree+0x116 sys/kern/kern_descrip.c:1181 exit1(ffff80003b0cecd8,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff80003b0cecd8,ffff80003c5186f0,ffff80003c518640) at sys_exit+0x1a syscall(ffff80003c5186f0) at syscall+0xb08 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c5186f0) at syscall+0xb08 sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72951e6eccc0, 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: 0x7c5584308820, 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: 0x7c5584308820, count: -3