panic: kernel diagnostic assertion "TAILQ_EMPTY(&kq->kq_head)" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_event.c", line 1268 Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *483275 29128 0 0 0x4000000 0 syz-executor.0 174656 62957 0 0x2 0x480 1 syz-executor.1 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff823c3c11) at panic+0x15e sys/kern/subr_prf.c:218 __assert(ffffffff8242d86c,ffffffff82425328,4f4,ffffffff823ad335) at __assert+0x2b sys/kern/subr_prf.c:162 kqueue_terminate(ffff8000214ac000,fffffd80686ec220) at kqueue_terminate+0x152 sys/kern/kern_event.c:1268 kqueue_close(fffffd8069a12130,ffff80002123c7e0) at kqueue_close+0x40 sys/kern/kern_event.c:1286 fdrop(fffffd8069a12130,ffff80002123c7e0) at fdrop+0xc2 sys/kern/kern_descrip.c:1279 closef(fffffd8069a12130,ffff80002123c7e0) at closef+0x11c sys/kern/kern_descrip.c:1263 finishdup(ffff80002123c7e0,fffffd8069a122f8,4,3,ffff8000222dfb40,2) at finishdup+0x321 sys/kern/kern_descrip.c:691 dodup3(ffff80002123c7e0,4,3,0,ffff8000222dfb40) at dodup3+0x5cf sys/kern/kern_descrip.c:397 syscall(ffff8000222dfbc0) at syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222dfbc0) at syscall+0x4a1 sys/arch/amd64/amd64/trap.c:590 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xff030cab130, count: 4 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 kernel diagnostic assertion "TAILQ_EMPTY(&kq->kq_head)" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_event.c", line 1268 ddb{0}> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff823c3c11) at panic+0x15e sys/kern/subr_prf.c:218 __assert(ffffffff8242d86c,ffffffff82425328,4f4,ffffffff823ad335) at __assert+0x2b sys/kern/subr_prf.c:162 kqueue_terminate(ffff8000214ac000,fffffd80686ec220) at kqueue_terminate+0x152 sys/kern/kern_event.c:1268 kqueue_close(fffffd8069a12130,ffff80002123c7e0) at kqueue_close+0x40 sys/kern/kern_event.c:1286 fdrop(fffffd8069a12130,ffff80002123c7e0) at fdrop+0xc2 sys/kern/kern_descrip.c:1279 closef(fffffd8069a12130,ffff80002123c7e0) at closef+0x11c sys/kern/kern_descrip.c:1263 finishdup(ffff80002123c7e0,fffffd8069a122f8,4,3,ffff8000222dfb40,2) at finishdup+0x321 sys/kern/kern_descrip.c:691 dodup3(ffff80002123c7e0,4,3,0,ffff8000222dfb40) at dodup3+0x5cf sys/kern/kern_descrip.c:397 syscall(ffff8000222dfbc0) at syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222dfbc0) at syscall+0x4a1 sys/arch/amd64/amd64/trap.c:590 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xff030cab130, count: -11 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff8000222df760 rbx 0xffff8000222df770 rdx 0x8b rcx 0x2 rax 0x1 r8 0xffffffff821c43c5 kprintf+0x145 r9 0x1 r10 0x2b1eb14d2e853785 r11 0x109c9fc891b5566b r12 0x3000000008 r13 0xffff8000222df810 r14 0x100 r15 0x1 rip 0xffffffff81df8258 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff8000222df750 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor.0) pid=483275 stat=onproc flags process=0 proc=4000000 pri=65, usrpri=65, nice=20 forw=0xffffffffffffffff, list=0xffff80002123cfc0,0xffffffff828cc870 process=0xffff800021235960 user=0xffff8000222da000, vmspace=0xfffffd80084968a0 estcpu=15, cpticks=2, pctcpu=0.0 user=0, sys=2, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 29128 158928 47874 0 2 0 syz-executor.0 29128 73032 47874 0 3 0x4000080 kqread syz-executor.0 *29128 483275 47874 0 7 0x4000000 syz-executor.0 62957 174656 24241 0 7 0x482 syz-executor.1 47874 72719 24241 0 2 0x2 syz-executor.0 24241 29677 86784 0 3 0x82 thrsleep syz-fuzzer 24241 212995 86784 0 3 0x4000082 thrsleep syz-fuzzer 24241 275826 86784 0 3 0x4000082 thrsleep syz-fuzzer 24241 60661 86784 0 3 0x4000082 kqread syz-fuzzer 24241 367464 86784 0 3 0x4000082 thrsleep syz-fuzzer 24241 105237 86784 0 3 0x4000082 thrsleep syz-fuzzer 24241 176077 86784 0 3 0x4000082 thrsleep syz-fuzzer 24241 251763 86784 0 3 0x4000082 thrsleep syz-fuzzer 86784 8880 42810 0 3 0x10008a sigsusp ksh 42810 418943 42095 0 3 0x92 select sshd 53128 95631 1 0 3 0x100083 ttyin getty 42095 323626 1 0 3 0x80 select sshd 42605 227811 15979 74 3 0x100092 bpf pflogd 15979 295403 1 0 3 0x80 netio pflogd 26789 111695 50244 73 3 0x100090 kqread syslogd 50244 1796 1 0 3 0x100082 netio syslogd 47110 346746 1 77 3 0x100090 poll dhclient 51936 62735 1 0 3 0x80 poll dhclient 86468 203016 0 0 3 0x14200 bored smr 6753 412620 0 0 2 0x14200 zerothread 83659 346568 0 0 3 0x14200 aiodoned aiodoned 46730 323586 0 0 3 0x14200 syncer update 25715 520712 0 0 3 0x14200 cleaner cleaner 34779 9088 0 0 3 0x14200 reaper reaper 85014 61930 0 0 3 0x14200 pgdaemon pagedaemon 81558 314126 0 0 3 0x14200 bored crynlk 38693 175608 0 0 3 0x14200 bored crypto 54336 125190 0 0 3 0x14200 bored viomb 13677 360890 0 0 3 0x40014200 acpi0 acpi0 50155 289024 0 0 3 0x40014200 idle1 58589 417037 0 0 3 0x14200 bored softnet 68316 241999 0 0 3 0x14200 bored systqmp 18871 326611 0 0 3 0x14200 bored systq 59609 359580 0 0 2 0x40014200 softclock 45042 464869 0 0 3 0x40014200 idle0 1 112848 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{0}> show all locks Process 29128 (syz-executor.0) thread 0xffff80002123c7e0 (483275) exclusive kernel_lock &kernel_lock r = 0 (0xffffffff828cca98) #0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline] #0 witness_lock+0x4b0 sys/kern/subr_witness.c:1176 #1 kqueue_close+0x2d sys/kern/kern_event.c:1284 #2 fdrop+0xc2 sys/kern/kern_descrip.c:1279 #3 closef+0x11c sys/kern/kern_descrip.c:1263 #4 finishdup+0x321 sys/kern/kern_descrip.c:691 #5 dodup3+0x5cf sys/kern/kern_descrip.c:397 #6 syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline] #6 syscall+0x4a1 sys/arch/amd64/amd64/trap.c:590 #7 Xsyscall+0x128 ddb{0}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 9490 6441K 6446K 78643K 26441 0 pcb 13 8K 8K 78643K 451 0 rtable 111 3K 3K 78643K 205 0 ifaddr 44 10K 10K 78643K 45 0 sysctl 2 0K 0K 78643K 2 0 counters 44 34K 34K 78643K 44 0 ioctlops 0 0K 4K 78643K 3005 0 iov 0 0K 16K 78643K 945 0 mount 1 1K 1K 78643K 1 0 vnodes 1222 77K 77K 78643K 10934 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 5K 78643K 168 0 VM map 2 1K 1K 78643K 2 0 sem 12 0K 0K 78643K 330 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12598 0 file desc 5 13K 25K 78643K 53845 0 proc 60 63K 95K 78643K 448 0 subproc 32 2K 2K 78643K 34 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 in_multi 33 2K 2K 78643K 33 0 ether_multi 1 0K 0K 78643K 1 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 55 254K 254K 78643K 55 0 exec 0 0K 2K 78643K 358 0 pagedep 1 8K 8K 78643K 1 0 inodedep 1 32K 32K 78643K 1 0 newblk 1 0K 0K 78643K 1 0 VM swap 7 26K 26K 78643K 7 0 UVM amap 185 26K 27K 78643K 124331 0 UVM aobj 131 4K 4K 78643K 267 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 NDP 6 0K 0K 78643K 10 0 temp 106 3981K 4047K 78643K 122538 0 kqueue 7 8K 15K 78643K 4691 0 SYN cache 2 16K 16K 78643K 2 0 ddb{0}> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle arp 64 6 0 0 1 0 1 1 0 8 0 plcache 128 20 0 0 1 0 1 1 0 8 0 rtpcb 120 19 0 17 1 0 1 1 0 8 0 rtentry 112 48 0 1 2 0 2 2 0 8 0 unpcb 120 16078 0 16068 1 0 1 1 0 8 0 syncache 296 4 0 4 1 1 0 1 0 8 0 tcpcb 736 400 0 396 14 13 1 6 0 8 0 inpcb 304 4936 0 4929 1 0 1 1 0 8 0 nd6 48 9 0 0 1 0 1 1 0 8 0 kcovpl 48 2 0 0 1 0 1 1 0 8 0 pffrag 232 8 0 8 4 3 1 1 0 482 1 pffrnode 88 7 0 7 4 3 1 1 0 8 1 pffrent 40 143 0 143 4 3 1 1 0 8 1 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 72 0 70 1 0 1 1 0 8 0 pfstkey 112 72 0 70 2 1 1 2 0 8 0 pfstate 328 72 0 70 5 4 1 4 0 8 0 pfrule 1360 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 256 193 0 0 13 0 13 13 0 8 0 art_table 32 194 0 0 2 0 2 2 0 8 0 art_node 16 47 0 4 1 0 1 1 0 8 0 semapl 112 328 0 318 1 0 1 1 0 8 0 shmpl 112 264 0 136 4 0 4 4 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 60661 0 59260 88 0 88 88 0 8 0 ffsino 272 60661 0 59260 94 0 94 94 0 8 0 nchpl 144 137840 0 136233 60 0 60 60 0 8 0 uvmvnodes 72 5926 0 0 108 0 108 108 0 8 0 vnodes 224 5926 0 0 349 0 349 349 0 8 0 namei 1024 370721 0 370721 1 0 1 1 0 8 1 percpumem 16 33 0 0 1 0 1 1 0 8 0 scxspl 216 345652 0 345652 9 8 1 8 0 8 1 plimitpl 152 181 0 173 1 0 1 1 0 8 0 sigapl 424 54061 0 54029 4 0 4 4 0 8 0 futexpl 56 235236 0 235236 3 2 1 1 0 8 1 knotepl 112 4654 0 4634 1 0 1 1 0 8 0 kqueuepl 168 6801 0 6716 6 2 4 4 0 8 0 pipepl 336 4427 0 4416 60 59 1 2 0 8 0 fdescpl 496 54045 0 54029 3 0 3 3 0 8 0 filepl 152 180810 0 180706 11 6 5 5 0 8 0 lockfpl 104 5184 0 5183 1 0 1 1 0 8 0 lockfspl 48 2142 0 2141 1 0 1 1 0 8 0 sessionpl 144 18 0 7 1 0 1 1 0 8 0 pgrppl 48 236 0 225 1 0 1 1 0 8 0 ucredpl 96 19810 0 19801 1 0 1 1 0 8 0 zombiepl 144 54029 0 54028 1 0 1 1 0 8 0 processpl 1080 54061 0 54028 3 0 3 3 0 8 0 procpl 672 123677 0 123635 8 4 4 5 0 8 0 sockpl 432 21059 0 21040 18 15 3 4 0 8 0 mcl64k 65536 35 0 0 4 1 3 3 0 8 0 mcl16k 16384 30 0 0 3 1 2 3 0 8 0 mcl12k 12288 72 0 0 3 1 2 2 0 8 0 mcl9k 9216 32 0 0 2 0 2 2 0 8 0 mcl8k 8192 27 0 0 3 0 3 3 0 8 0 mcl4k 4096 25 0 0 4 1 3 3 0 8 0 mcl2k2 2112 26 0 0 2 0 2 2 0 8 0 mcl2k 2048 178 0 0 13 1 12 12 0 8 0 mtagpl 96 1 0 0 1 0 1 1 0 8 0 mbufpl 256 1543 0 0 18 3 15 18 0 8 0 bufpl 280 57692 0 51445 447 0 447 447 0 8 0 anonpl 24 3382145 0 3376960 63 27 36 59 0 186 0 amapchunkpl 152 194273 0 194099 16 8 8 8 0 158 0 amappl16 200 165683 0 165504 32 21 11 23 0 8 0 amappl15 192 2 0 0 1 0 1 1 0 8 0 amappl14 184 26692 0 26686 1 0 1 1 0 8 0 amappl13 176 27 0 24 1 0 1 1 0 8 0 amappl12 168 5 0 3 1 0 1 1 0 8 0 amappl11 160 27214 0 27196 1 0 1 1 0 8 0 amappl10 152 15 0 9 1 0 1 1 0 8 0 amappl9 144 283 0 283 1 1 0 1 0 8 0 amappl8 136 1264 0 1128 5 0 5 5 0 8 0 amappl7 128 243 0 235 1 0 1 1 0 8 0 amappl6 120 69 0 57 1 0 1 1 0 8 0 amappl5 112 55640 0 55622 1 0 1 1 0 8 0 amappl4 104 27671 0 27645 1 0 1 1 0 8 0 amappl3 96 3359 0 3351 1 0 1 1 0 8 0 amappl2 88 459003 0 458931 3 1 2 3 0 8 0 amappl1 80 1497475 0 1497001 27 15 12 21 0 8 0 amappl 88 123914 0 123862 2 0 2 2 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 128 253 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 64 266 0 136 3 0 3 3 0 8 0 uaddrrnd 24 54045 0 54029 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 54045 0 54029 1 0 1 1 0 8 0 vmmpekpl 168 310292 0 310267 2 0 2 2 0 8 0 vmmpepl 168 6664272 0 6662770 190 118 72 83 0 357 1 vmsppl 368 54044 0 54029 2 0 2 2 0 8 0 rwobjpl 56 1381814 0 1380843 50 35 15 19 0 8 0 pdppl 4096 108097 0 108058 57 16 41 45 0 8 2 pvpl 32 10536487 0 10528244 232 158 74 117 0 265 0 pmappl 232 54044 0 54029 2 1 1 2 0 8 0 extentpl 40 58 0 40 1 0 1 1 0 8 0 phpool 112 383 0 98 9 0 9 9 0 8 0 ddb{0}> machine ddbcpu 0 Invalid cpu 0 ddb{0}> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff823c3c11) at panic+0x15e sys/kern/subr_prf.c:218 __assert(ffffffff8242d86c,ffffffff82425328,4f4,ffffffff823ad335) at __assert+0x2b sys/kern/subr_prf.c:162 kqueue_terminate(ffff8000214ac000,fffffd80686ec220) at kqueue_terminate+0x152 sys/kern/kern_event.c:1268 kqueue_close(fffffd8069a12130,ffff80002123c7e0) at kqueue_close+0x40 sys/kern/kern_event.c:1286 fdrop(fffffd8069a12130,ffff80002123c7e0) at fdrop+0xc2 sys/kern/kern_descrip.c:1279 closef(fffffd8069a12130,ffff80002123c7e0) at closef+0x11c sys/kern/kern_descrip.c:1263 finishdup(ffff80002123c7e0,fffffd8069a122f8,4,3,ffff8000222dfb40,2) at finishdup+0x321 sys/kern/kern_descrip.c:691 dodup3(ffff80002123c7e0,4,3,0,ffff8000222dfb40) at dodup3+0x5cf sys/kern/kern_descrip.c:397 syscall(ffff8000222dfbc0) at syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222dfbc0) at syscall+0x4a1 sys/arch/amd64/amd64/trap.c:590 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xff030cab130, count: -11 ddb{0}> machine ddbcpu 1