panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 953 Stopped at db_enter+37: addq $8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 31941 52500 0 0x2 0 1 syz-executor db_enter() at db_enter+37 panic(ffffffff833943a7) at panic+485 __assert(ffffffff833d16ba,ffffffff833e4470,3b9,ffffffff8340e057) at __assert+41 refcnt_finalize(ffff80002a7cf580,ffffffff83384e88) at refcnt_finalize+475 pppx_if_destroy(285b9a,ffff80002a7cf578) at pppx_if_destroy+61 pppxclose(285b9a,1,2000,ffff80003c463cc0) at pppxclose+160 spec_close(ffff80002a31e600) at spec_close+1047 VOP_CLOSE(fffffd806e054870,1,fffffd80097fb618,ffff80003c463cc0) at VOP_CLOSE+306 vn_closefile(fffffd806c210ad0,ffff80003c463cc0) at vn_closefile+299 fdrop(fffffd806c210ad0,ffff80003c463cc0) at fdrop+289 closef(fffffd806c210ad0,ffff80003c463cc0) at closef+402 fdfree(ffff80003c463cc0) at fdfree+278 exit1(ffff80003c463cc0,0,0,1) at exit1+1398 sys_exit(ffff80003c463cc0,ffff80002a31e970,ffff80002a31e8c0) at sys_exit+26 end trace frame: 0xffff80002a31e960, 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 953 ddb{0}> trace db_enter() at db_enter+37 panic(ffffffff833943a7) at panic+485 __assert(ffffffff833d16ba,ffffffff833e4470,3b9,ffffffff8340e057) at __assert+41 refcnt_finalize(ffff80002a7cf580,ffffffff83384e88) at refcnt_finalize+475 pppx_if_destroy(285b9a,ffff80002a7cf578) at pppx_if_destroy+61 pppxclose(285b9a,1,2000,ffff80003c463cc0) at pppxclose+160 spec_close(ffff80002a31e600) at spec_close+1047 VOP_CLOSE(fffffd806e054870,1,fffffd80097fb618,ffff80003c463cc0) at VOP_CLOSE+306 vn_closefile(fffffd806c210ad0,ffff80003c463cc0) at vn_closefile+299 fdrop(fffffd806c210ad0,ffff80003c463cc0) at fdrop+289 closef(fffffd806c210ad0,ffff80003c463cc0) at closef+402 fdfree(ffff80003c463cc0) at fdfree+278 exit1(ffff80003c463cc0,0,0,1) at exit1+1398 sys_exit(ffff80003c463cc0,ffff80002a31e970,ffff80002a31e8c0) at sys_exit+26 syscall(ffff80002a31e970) at syscall+2839 Xsyscall() at Xsyscall+296 end of kernel end trace frame: 0x74c157424d10, count: -16 ddb{0}> show registers rdi 0 rsi 1 rbp 18446603336929108944 rbx 18446744071621283295 cpu_info_full_primary+11743 rdx 0 rcx 18446603337232432320 rax 18446744071621279728 cpu_info_full_primary+8176 r8 72340172838076673 r9 9259542123273814144 r10 3688331665349045764 r11 11644887011100172201 r12 18446744071621282784 cpu_info_full_primary+11232 r13 0 r14 0 r15 1 rip 18446744071579008149 db_enter+37 cs 8 rflags 582 rsp 18446603336929108928 ss 16 db_enter+37: addq $8,%rsp ddb{0}> show proc PROC (syz-executor) tid=406475 pid=75996 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80003c463cc0 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80003c463790,0xffff8000fffee7f0 process=0xffff80003c41eb80 user=0xffff80002a319000, vmspace=0xfffffd80657cc210 estcpu=36, cpticks=35, pctcpu=0.0, user=0, sys=1, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 83931 195451 34886 0 2 0 syz-executor 94088 337668 38030 0 2 0 syz-executor 63017 433075 52500 0 2 0 syz-executor 63017 142268 52500 0 3 0x4000000 getblk syz-executor 42012 482891 79714 0 2 0x100002 sh 52133 361429 31907 0 3 0x80 nanoslp syz-executor 52133 191792 31907 0 3 0x4000000 smrbar syz-executor 52133 337293 31907 0 3 0x4000080 fsleep syz-executor 66561 420547 53793 0 3 0x80 nanoslp syz-executor 66561 63168 53793 0 3 0x4000080 sbwait syz-executor 66561 177584 53793 0 3 0x4000080 fsleep syz-executor 66561 327735 53793 0 3 0x4000080 fsleep syz-executor 79714 161681 45706 0 3 0x82 wait syz-executor 93940 232225 45706 0 2 0x2 syz-executor 73353 208937 45706 0 2 0x2 syz-executor 38030 159128 45706 0 2 0x3 syz-executor 53793 507588 45706 0 2 0x2 syz-executor 31907 453348 45706 0 3 0x82 nanoslp syz-executor 34886 486089 45706 0 2 0xc82 syz-executor 52500 31941 45706 0 7 0x2 syz-executor 93849 406553 1 0 3 0x100083 ttyopn getty 45706 292815 47575 0 2 0x2 syz-executor 47575 394604 5247 0 3 0x10008a sigsusp ksh 5247 264504 55019 0 3 0x98 kqread sshd-session 55019 197454 86897 0 3 0x92 kqread sshd-session 86897 240689 1 0 3 0x88 kqread sshd 36194 426468 45652 74 3 0x1100092 bpf pflogd 45652 245894 1 0 3 0x80 sbwait pflogd 52892 267468 68255 73 3 0x1100090 kqread syslogd 68255 180043 1 0 3 0x100082 sbwait syslogd 3934 186571 1 0 3 0x100080 kqread resolvd 16271 324050 60947 77 3 0x100092 kqread dhcpleased 96524 449070 60947 77 3 0x100092 kqread dhcpleased 60947 97929 1 0 3 0x80 kqread dhcpleased 36349 399673 0 0 3 0x14200 bored smr 23137 137850 0 0 2 0x14200 zerothread 13110 332220 0 0 3 0x14200 aiodoned aiodoned 74985 259209 0 0 3 0x14200 syncer update 10926 415265 0 0 3 0x14200 cleaner cleaner 46630 419860 0 0 2 0x14200 reaper 20324 15426 0 0 3 0x14200 pgdaemon pagedaemon 90031 96811 0 0 3 0x14200 bored viomb 62818 134865 0 0 3 0x40014200 acpi0 acpi0 20990 46384 0 0 3 0x40014200 idle1 93156 369305 0 0 3 0x14200 bored softnet1 54971 55987 0 0 3 0x14200 bored softnet0 71144 452242 0 0 3 0x14200 bored systqmp 80226 516312 0 0 3 0x14200 bored systq 36930 307282 0 0 3 0x14200 tmoslp softclockmp 72145 111249 0 0 3 0x40014200 tmoslp softclock 18013 31654 0 0 3 0x40014200 idle0 1 340510 0 0 3 0x82 wait init 0 0 -1 0 3 0x10010200 scheduler swapper ddb{0}> show all locks Process 94088 (syz-executor) thread 0xffff8000fffefca0 (337668) exclusive rrwlock inode r = 0 (0xfffffd8067fbb338) #0 witness_lock+1521 #1 rw_do_enter_write+1049 #2 rrw_enter+198 #3 VOP_LOCK+163 #4 vn_lock+164 #5 vget+674 #6 ufs_ihashget+389 #7 ffs_vget+140 #8 ufs_lookup+5821 #9 VOP_LOOKUP+110 #10 vfs_lookup+2362 #11 namei+1994 #12 sys_chdir+136 #13 syscall+2839 #14 Xsyscall+296 Process 63017 (syz-executor) thread 0xffff8000fffee018 (142268) exclusive rrwlock inode r = 0 (0xfffffd806c18e208) #0 witness_lock+1521 #1 rw_do_enter_write+1049 #2 rrw_enter+198 #3 VOP_LOCK+163 #4 ufs_ihashins+79 #5 ffs_vget+391 #6 ffs_inode_alloc+633 #7 ufs_makeinode+205 #8 ufs_mknod+91 #9 VOP_MKNOD+257 #10 domknodat+1129 #11 syscall+2839 #12 Xsyscall+296 exclusive rrwlock inode r = 0 (0xfffffd806e066ed8) #0 witness_lock+1521 #1 rw_do_enter_write+1049 #2 rrw_enter+198 #3 VOP_LOCK+163 #4 vn_lock+164 #5 vfs_lookup+284 #6 namei+1994 #7 domknodat+180 #8 syscall+2839 #9 Xsyscall+296 Process 42012 (sh) thread 0xffff80003c462d30 (482891) exclusive rwlock vmmaplk r = 0 (0xfffffd806ae24500) #0 witness_lock+1521 #1 rw_do_enter_write+1049 #2 vm_map_lock_ln+302 #3 uvmspace_fork+68 #4 process_new+1399 #5 fork1+1014 #6 syscall+2839 #7 Xsyscall+296 Process 73353 (syz-executor) thread 0xffff800033fd4aa0 (208937) exclusive rrwlock inode r = 0 (0xfffffd806aed1a38) #0 witness_lock+1521 #1 rw_do_enter_write+1049 #2 rrw_enter+198 #3 VOP_LOCK+163 #4 ufs_ihashins+79 #5 ffs_vget+391 #6 ffs_inode_alloc+633 #7 ufs_mkdir+252 #8 VOP_MKDIR+257 #9 domkdirat+377 #10 syscall+2839 #11 Xsyscall+296 exclusive rrwlock inode r = 0 (0xfffffd806e7e3d90) #0 witness_lock+1521 #1 rw_do_enter_write+1049 #2 rrw_enter+198 #3 VOP_LOCK+163 #4 vn_lock+164 #5 vfs_lookup+284 #6 namei+1994 #7 domkdirat+139 #8 syscall+2839 #9 Xsyscall+296 Process 46630 (reaper) thread 0xffff8000ffffd4c8 (419860) exclusive rwlock kmmaplk r = 0 (0xffffffff8389b4d8) #0 witness_lock+1521 #1 rw_do_enter_write+1049 #2 vm_map_lock_ln+302 #3 uvm_unmap+125 #4 km_free+135 #5 uvm_uarea_free+79 #6 reaper+426 #7 proc_trampoline+16 ddb{0}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10244 11047K 12495K 166960K 18410 0 pcb 19 17K 22K 166960K 1299 0 rtable 280 19K 20K 166960K 2007 0 pf 49 20K 67488K 166960K 900 0 ifaddr 46 11K 12K 166960K 488 0 ifgroup 64 2K 3K 166960K 1007 0 sysctl 4 1K 9K 166960K 114 0 counters 74 37K 38K 166960K 1382 0 ioctlops 0 0K 5K 166960K 3415 0 iov 0 0K 24K 166960K 600 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1487 93K 94K 166960K 6664 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 48K 56K 166960K 98 0 VM map 2 1K 1K 166960K 2 0 sem 59 155K 155K 166960K 323 0 dirhash 12 2K 2K 166960K 162 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 240K 166960K 6447 0 sigio 0 0K 0K 166960K 391 0 proc 73 115K 180K 166960K 1695 0 subproc 72 4K 4K 166960K 235 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 892 0 in_multi 87 6K 7K 166960K 589 0 ether_multi 1 0K 0K 166960K 101 0 mrt 1 0K 0K 166960K 46 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 265 1182K 1182K 166960K 265 0 exec 0 0K 1K 166960K 1922 0 fusefs mount 1 32K 32K 166960K 1 0 pfkey data 0 0K 0K 166960K 9 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 245 161K 177K 166960K 59469 0 UVM aobj 44 6K 6K 166960K 47 0 pinsyscall 43 86K 102K 166960K 7964 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 1K 166960K 486 0 NDP 14 0K 1K 166960K 367 0 temp 155 8661K 8778K 166960K 366314 0 kqueue 16 22K 34K 166960K 1407 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 26 0 0 1 0 1 1 0 8 0 rtpcb 120 888 0 885 9 8 1 2 0 8 0 rtentry 176 541 0 443 5 0 5 5 0 8 0 unpcb 144 5415 0 5392 51 50 1 7 0 8 0 syncache 336 7 0 7 5 5 0 1 0 8 0 tcpqe 32 1 0 1 1 1 0 1 0 8 0 tcpcb 736 2494 0 2490 56 52 4 7 0 8 3 arp 136 71 0 51 1 0 1 1 0 8 0 inpcb 328 8055 0 8044 96 89 7 18 0 8 5 nd6 152 95 0 73 2 1 1 2 0 8 0 pkpcb 40 117 0 117 17 16 1 1 0 8 1 kcovpl 48 26 0 18 1 0 1 1 0 8 0 mppekey 1024 7 0 7 7 7 0 1 0 8 0 ppxss 1192 528 0 527 8 7 1 1 0 8 0 pppxif 1504 114 0 113 20 19 1 1 0 8 0 pfstscr 40 6 0 6 2 2 0 1 0 8 0 pffrag 232 58 0 55 1 0 1 1 0 482 0 pffrnode 88 47 0 44 1 0 1 1 0 8 0 pffrent 40 128 0 125 1 0 1 1 0 8 0 pfosfp 40 1429 0 1005 5 0 5 5 0 8 0 pfosfpen 112 1429 0 714 21 0 21 21 0 8 0 pfrktable 1344 13 0 9 1 0 1 1 0 8 0 pfanchor 1288 2 0 0 1 0 1 1 0 8 0 pftag 88 2 0 0 1 0 1 1 0 8 0 pfstitem 24 500 0 435 1 0 1 1 0 8 0 pfstkey 128 516 0 453 4 0 4 4 0 8 0 pfstate 384 505 0 443 15 7 8 13 0 8 0 pfrule 1344 52 0 37 3 1 2 2 0 8 0 rttmr 136 7 0 7 5 5 0 1 0 8 0 art_heap8 4096 6 0 1 6 0 6 6 0 8 1 art_heap4 256 2181 0 1778 55 29 26 29 0 8 0 art_table 40 2187 0 1779 5 0 5 5 0 8 0 art_node 32 522 0 438 1 0 1 1 0 8 0 sysvmsgpl 40 13 0 7 1 0 1 1 0 8 0 semupl 112 1 0 1 1 1 0 1 0 8 0 semapl 112 315 0 258 2 0 2 2 0 8 0 shmpl 112 44 0 3 2 0 2 2 0 8 0 dirhash 1024 117 0 100 3 0 3 3 0 8 0 dino2pl 256 13785 0 12235 98 0 98 98 0 8 0 ffsino 296 13786 0 12235 120 0 120 120 0 8 0 nchpl 144 22682 0 22009 65 39 26 64 0 8 0 rtmask 32 59 0 59 14 13 1 1 0 8 1 vnodes 216 5926 0 0 330 0 330 330 0 8 0 namei 1024 83875 0 83872 10 9 1 2 0 8 0 percpumem 16 706 0 654 1 0 1 1 0 8 0 pfiaddrpl 120 4 0 0 1 0 1 1 0 8 0 kstatmem 264 634 0 602 5 2 3 3 0 8 0 acpiwqpl 32 2 0 2 1 0 1 1 1 8 1 scsiplug 72 39 0 39 16 15 1 1 0 8 1 scxspl 216 139660 0 139660 18 17 1 7 1 8 1 plimitpl 152 1800 0 1783 1 0 1 1 0 8 0 sigapl 424 6714 0 6666 9 2 7 8 0 8 0 knotepl 120 1111 0 0 25 0 25 25 0 8 0 kqueuepl 224 3441 0 3431 42 41 1 5 0 8 0 pipepl 344 952 0 925 14 11 3 9 0 8 0 fdescpl 528 6645 0 6613 3 0 3 3 0 8 0 filepl 160 52290 0 52068 71 58 13 21 0 8 2 lockfpl 104 2703 0 2664 6 4 2 2 0 8 0 lockfspl 48 1086 0 1050 1 0 1 1 0 8 0 sessionpl 144 41 0 32 1 0 1 1 0 8 0 pgrppl 48 347 0 330 1 0 1 1 0 8 0 ucredpl 104 9236 0 9223 1 0 1 1 0 8 0 zombiepl 144 9529 0 9528 1 0 1 1 0 8 0 processpl 1232 6714 0 6666 7 2 5 6 0 8 0 procpl 664 17604 0 17547 9 2 7 8 0 8 1 sosppl 176 56 0 56 20 19 1 1 0 8 1 sockpl 752 14728 0 14691 196 187 9 30 0 8 5 mcl64k 65536 57 0 0 6 1 5 5 0 8 0 mcl16k 16384 3 0 0 1 0 1 1 0 8 0 mcl12k 12288 2 0 0 1 0 1 1 0 8 0 mcl9k 9216 1 0 0 1 0 1 1 0 8 0 mcl8k 8192 2 0 0 1 0 1 1 0 8 0 mcl4k 4096 115 0 0 15 0 15 15 0 8 0 mcl2k2 2112 1 0 0 1 0 1 1 0 8 0 mcl2k 2048 162 0 0 10 2 8 10 0 8 1 mtagpl 96 13 0 0 1 0 1 1 0 8 0 mbufpl 256 1872 0 0 111 0 111 111 0 8 0 bufpl 280 53396 0 47259 439 0 439 439 0 8 0 anonpl 32 23520 0 0 188 0 188 188 0 246 0 amapchunkpl 152 226751 0 226107 151 108 43 45 0 158 9 amappl16 200 22046 0 21442 137 92 45 55 0 8 0 amappl15 192 10 0 9 1 0 1 1 0 8 0 amappl14 184 4 0 4 2 2 0 1 0 8 0 amappl13 176 639 0 637 1 0 1 1 0 8 0 amappl12 168 7106 0 7064 3 0 3 3 0 8 0 amappl11 160 5 0 5 1 1 0 1 0 8 0 amappl10 152 53 0 38 1 0 1 1 0 8 0 amappl9 144 295 0 294 2 1 1 1 0 8 0 amappl8 136 32 0 29 1 0 1 1 0 8 0 amappl7 128 178 0 176 1 0 1 1 0 8 0 amappl6 120 499 0 484 1 0 1 1 0 8 0 amappl5 112 72 0 61 1 0 1 1 0 8 0 amappl4 104 520 0 487 1 0 1 1 0 8 0 amappl3 96 38239 0 38152 4 1 3 3 0 8 0 amappl2 88 6706 0 6628 2 0 2 2 0 8 0 amappl1 80 35432 0 34837 14 1 13 14 0 8 0 amappl 88 57400 0 57233 5 0 5 5 0 92 0 uvmvnodes 80 5926 0 0 121 0 121 121 0 8 0 dma65536 65536 3 0 3 2 2 0 1 0 8 0 dma16384 16384 1 0 1 1 1 0 1 0 8 0 dma4096 4096 3 0 3 3 3 0 1 0 8 0 dma1024 1024 2 0 1 1 0 1 1 0 8 0 dma256 256 8 0 8 3 3 0 1 0 8 0 dma128 128 264 0 264 9 8 1 1 0 8 1 dma64 64 8 0 8 3 3 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 46 0 3 1 0 1 1 0 8 0 uaddrrnd 24 6644 0 6613 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 6644 0 6613 1 0 1 1 0 8 0 vmmpekpl 168 45202 0 45141 4 0 4 4 0 8 0 vmmpepl 168 423826 0 421308 277 138 139 147 0 357 8 vmsppl 488 6644 0 6613 7 2 5 5 0 8 0 rwobjpl 80 108613 0 101108 180 21 159 164 0 8 0 pdppl 4096 13296 0 13226 158 86 72 86 0 8 2 pvpl 32 32279 0 0 259 0 259 259 0 265 0 pmappl 256 6644 0 6613 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 555 0 200 11 0 11 11 0 8 0 ddb{0}> machine ddbcpu 0 Invalid cpu 0 ddb{0}> trace db_enter() at db_enter+37 panic(ffffffff833943a7) at panic+485 __assert(ffffffff833d16ba,ffffffff833e4470,3b9,ffffffff8340e057) at __assert+41 refcnt_finalize(ffff80002a7cf580,ffffffff83384e88) at refcnt_finalize+475 pppx_if_destroy(285b9a,ffff80002a7cf578) at pppx_if_destroy+61 pppxclose(285b9a,1,2000,ffff80003c463cc0) at pppxclose+160 spec_close(ffff80002a31e600) at spec_close+1047 VOP_CLOSE(fffffd806e054870,1,fffffd80097fb618,ffff80003c463cc0) at VOP_CLOSE+306 vn_closefile(fffffd806c210ad0,ffff80003c463cc0) at vn_closefile+299 fdrop(fffffd806c210ad0,ffff80003c463cc0) at fdrop+289 closef(fffffd806c210ad0,ffff80003c463cc0) at closef+402 fdfree(ffff80003c463cc0) at fdfree+278 exit1(ffff80003c463cc0,0,0,1) at exit1+1398 sys_exit(ffff80003c463cc0,ffff80002a31e970,ffff80002a31e8c0) at sys_exit+26 syscall(ffff80002a31e970) at syscall+2839 Xsyscall() at Xsyscall+296 end of kernel end trace frame: 0x74c157424d10, count: -16 ddb{0}> machine ddbcpu 1 Stopped at x86_ipi_db+39: addq $8,%rsp x86_ipi_db(ffff8000299edff0) at x86_ipi_db+39 x86_ipi_handler() at x86_ipi_handler+217 Xresume_lapic_ipi() at Xresume_lapic_ipi+39 __sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc+61 syscall(ffff80003a3f1dd0) at syscall+2804 Xsyscall() at Xsyscall+296 end of kernel end trace frame: 0x72d39d729d10, count: 9 ddb{1}> trace x86_ipi_db(ffff8000299edff0) at x86_ipi_db+39 x86_ipi_handler() at x86_ipi_handler+217 Xresume_lapic_ipi() at Xresume_lapic_ipi+39 __sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc+61 syscall(ffff80003a3f1dd0) at syscall+2804 Xsyscall() at Xsyscall+296 end of kernel end trace frame: 0x72d39d729d10, count: -6