panic: mutex 0xfffffd806e9a9af8 not held in knote_dequeue Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 352233 54917 32767 0x10 0 1 syz-executor.0 * 41166 54917 32767 0x10 0x4000000 0K syz-executor.0 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic(ffffffff8246025e) at panic+0x177 sys/kern/subr_prf.c:202 knote_dequeue(fffffd806e8a4690) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000256ba9d0,fffffd806e8a4690) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9a9af8,ffff8000256ba9d0,ffff8000ffff5508) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9a9af8,ffff8000256ba9d0,ffff8000ffff5508) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff8000ffff5508,ffff8000256bac88,ffff8000256bacd0) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000256bad50) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000256bad50) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x9089f0f6400, count: 7 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: mutex 0xfffffd806e9a9af8 not held in knote_dequeue ddb{0}> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic(ffffffff8246025e) at panic+0x177 sys/kern/subr_prf.c:202 knote_dequeue(fffffd806e8a4690) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000256ba9d0,fffffd806e8a4690) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9a9af8,ffff8000256ba9d0,ffff8000ffff5508) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9a9af8,ffff8000256ba9d0,ffff8000ffff5508) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff8000ffff5508,ffff8000256bac88,ffff8000256bacd0) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000256bad50) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000256bad50) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x9089f0f6400, count: -8 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff8000256ba7c0 rbx 0xffffffff8270abf7 cpu_info_full_primary+0x2bf7 rdx 0x8b rcx 0x2 rax 0x3a r8 0xffffffff81bb3f14 kprintf+0x144 r9 0x1 r10 0x897db90f52284d86 r11 0x3e0f6550d6585759 r12 0xffffffff8270a9f8 cpu_info_full_primary+0x29f8 r13 0 r14 0 r15 0x1 rip 0xffffffff81b43698 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff8000256ba7b0 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor.0) pid=41166 stat=onproc flags process=10 proc=4000000 pri=32, usrpri=74, nice=20 forw=0xffffffffffffffff, list=0xffff8000ffff4008,0xffffffff828f5570 process=0xffff8000ffff1100 user=0xffff8000256b5000, vmspace=0xfffffd807f009730 estcpu=24, cpticks=0, pctcpu=0.0 user=0, sys=0, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 54917 352233 61064 32767 7 0x10 syz-executor.0 54917 328885 61064 32767 3 0x4000090 kqread syz-executor.0 54917 354254 61064 32767 3 0x4000090 kqread syz-executor.0 54917 510425 61064 32767 2 0x4000010 syz-executor.0 *54917 41166 61064 32767 7 0x4000010 syz-executor.0 56177 466349 12262 32767 3 0x90 nanoslp syz-executor.1 12262 217506 10834 0 3 0x82 wait syz-executor.1 35884 249126 0 0 3 0x14200 bored sosplice 61064 138711 15237 32767 3 0x90 nanoslp syz-executor.0 15237 89101 10834 0 3 0x82 wait syz-executor.0 10834 217639 96686 0 3 0x82 thrsleep syz-fuzzer 10834 309868 96686 0 3 0x4000082 thrsleep syz-fuzzer 10834 28424 96686 0 3 0x4000082 kqread syz-fuzzer 10834 378298 96686 0 3 0x4000082 thrsleep syz-fuzzer 10834 53292 96686 0 3 0x4000082 thrsleep syz-fuzzer 10834 499682 96686 0 3 0x4000082 thrsleep syz-fuzzer 10834 176095 96686 0 3 0x4000082 thrsleep syz-fuzzer 10834 507296 96686 0 3 0x4000082 thrsleep syz-fuzzer 96686 384760 52745 0 3 0x10008a sigsusp ksh 52745 338469 77341 0 3 0x92 select sshd 37164 390136 1 0 3 0x100083 ttyin getty 77341 294651 1 0 3 0x80 select sshd 74361 378150 35926 73 3 0x100090 kqread syslogd 35926 266265 1 0 3 0x100082 netio syslogd 46197 344221 1 77 3 0x100090 poll dhclient 46190 212831 1 0 3 0x80 poll dhclient 91023 268852 0 0 3 0x14200 bored smr 2166 285896 0 0 3 0x14200 pgzero zerothread 35320 108944 0 0 3 0x14200 aiodoned aiodoned 35213 183117 0 0 3 0x14200 syncer update 63256 467627 0 0 3 0x14200 cleaner cleaner 16145 328123 0 0 3 0x14200 reaper reaper 21552 169935 0 0 3 0x14200 pgdaemon pagedaemon 80596 246036 0 0 3 0x14200 bored crynlk 77743 138873 0 0 3 0x14200 bored crypto 74085 495472 0 0 3 0x14200 bored viomb 22128 447337 0 0 3 0x40014200 acpi0 acpi0 71882 408523 0 0 3 0x40014200 idle1 76316 303274 0 0 3 0x14200 bored softnet 99185 281181 0 0 3 0x14200 bored systqmp 36149 483266 0 0 3 0x14200 bored systq 40004 412236 0 0 3 0x40014200 bored softclock 90922 234893 0 0 3 0x40014200 idle0 1 355252 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{0}> show all locks Process 54917 (syz-executor.0) thread 0xffff8000ffff5508 (41166) exclusive kernel_lock &kernel_lock r = 1 (0xffffffff8294f968) #0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline] #0 witness_lock+0x4b0 sys/kern/subr_witness.c:1182 #1 syscall+0x439 mi_syscall sys/sys/syscall_mi.h:93 [inline] #1 syscall+0x439 sys/arch/amd64/amd64/trap.c:587 #2 Xsyscall+0x128 ddb{0}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10118 6414K 6414K 78643K 11211 0 pcb 13 8K 8K 78643K 13 0 rtable 105 3K 3K 78643K 260 0 ifaddr 39 10K 10K 78643K 46 0 counters 44 34K 34K 78643K 46 0 ioctlops 0 0K 2K 78643K 26 0 iov 0 0K 16K 78643K 51 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 1 0 vnodes 1216 76K 76K 78643K 1270 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 1K 78643K 2 0 VM map 2 1K 1K 78643K 2 0 sem 12 0K 0K 78643K 910 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12598 0 file desc 7 21K 33K 78643K 1428 0 sigio 0 0K 0K 78643K 10 0 proc 48 50K 83K 78643K 420 0 subproc 34 2K 2K 78643K 51 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 ip_moptions 0 0K 0K 78643K 96 0 in_multi 33 2K 2K 78643K 69 0 ether_multi 1 0K 0K 78643K 9 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 49 228K 228K 78643K 49 0 exec 0 0K 2K 78643K 429 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 258 37K 49K 78643K 19064 0 UVM aobj 8 2K 2K 78643K 18 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 46 0 NDP 5 0K 0K 78643K 12 0 temp 102 3989K 4053K 78643K 4802 0 kqueue 13 8K 12K 78643K 92 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 plcache 128 22 0 0 1 0 1 1 0 8 0 rtpcb 120 60 0 58 1 0 1 1 0 8 0 rtentry 112 56 0 12 2 0 2 2 0 8 0 unpcb 120 461 0 452 1 0 1 1 0 8 0 syncache 296 21 0 21 3 3 0 1 0 8 0 tcpqe 32 981 0 981 3 3 0 2 0 8 0 tcpcb 736 299 0 290 4 2 2 3 0 8 0 arp 120 8 0 2 1 0 1 1 0 8 0 ipq 40 2 0 2 1 0 1 1 0 8 1 ipqe 40 4 0 4 1 0 1 1 0 8 1 inpcb 304 680 0 673 4 2 2 2 0 8 1 ip6q 72 1 0 1 1 1 0 1 0 8 0 ip6af 40 2 0 2 1 1 0 1 0 8 0 nd6 48 9 0 3 1 0 1 1 0 8 0 kcovpl 48 3 0 1 1 0 1 1 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 232 0 44 12 0 12 12 0 8 0 art_table 32 233 0 44 2 0 2 2 0 8 0 art_node 16 55 0 15 1 0 1 1 0 8 0 semupl 112 9 0 9 1 1 0 1 0 8 0 semapl 112 908 0 898 1 0 1 1 0 8 0 shmpl 112 15 0 10 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 3020 0 1621 88 0 88 88 0 8 0 ffsino 272 3020 0 1621 94 0 94 94 0 8 0 nchpl 144 5121 0 3523 60 0 60 60 0 8 0 uvmvnodes 72 3080 0 0 56 0 56 56 0 8 0 vnodes 224 3080 0 0 182 0 182 182 0 8 0 namei 1024 11890 0 11890 2 1 1 1 0 8 1 percpumem 16 35 0 1 1 0 1 1 0 8 0 scxspl 216 16733 0 16733 14 10 4 8 0 8 4 plimitpl 152 49 0 40 1 0 1 1 0 8 0 sigapl 424 1613 0 1580 4 0 4 4 0 8 0 futexpl 56 19380 0 19380 1 0 1 1 0 8 1 knotepl 112 33 0 0 1 0 1 1 0 8 0 kqueuepl 216 1873 0 1862 1 0 1 1 0 8 0 pipepl 336 149 0 138 4 2 2 2 0 8 1 fdescpl 496 1596 0 1580 3 0 3 3 0 8 0 filepl 152 6827 0 6720 7 2 5 5 0 8 0 lockfpl 104 124 0 123 1 0 1 1 0 8 0 lockfspl 48 47 0 46 1 0 1 1 0 8 0 sessionpl 144 18 0 8 1 0 1 1 0 8 0 pgrppl 48 18 0 8 1 0 1 1 0 8 0 ucredpl 96 609 0 600 1 0 1 1 0 8 0 zombiepl 144 1580 0 1579 2 1 1 1 0 8 0 processpl 1080 1613 0 1579 5 2 3 3 0 8 0 procpl 672 3584 0 3539 7 2 5 5 0 8 1 sosppl 168 53 0 53 3 2 1 1 0 8 1 sockpl 480 1211 0 1193 7 3 4 5 0 8 1 mcl64k 65536 8 0 0 1 0 1 1 0 8 0 mcl16k 16384 6 0 0 1 0 1 1 0 8 0 mcl12k 12288 9 0 0 1 0 1 1 0 8 0 mcl9k 9216 3 0 0 1 0 1 1 0 8 0 mcl8k 8192 6 0 0 1 0 1 1 0 8 0 mcl4k 4096 17 0 0 3 0 3 3 0 8 0 mcl2k2 2112 4 0 0 1 0 1 1 0 8 0 mcl2k 2048 321 0 0 40 0 40 40 0 8 0 mtagpl 96 1 0 0 1 0 1 1 0 8 0 mbufpl 256 1003 0 0 61 1 60 60 0 8 0 bufpl 280 6433 0 141 450 0 450 450 0 8 0 anonpl 24 430233 0 402030 179 4 175 176 0 186 0 amapchunkpl 152 44942 0 44085 46 10 36 46 0 158 0 amappl16 200 3687 0 2624 60 2 58 58 0 8 1 amappl15 192 59 0 53 1 0 1 1 0 8 0 amappl14 184 458 0 456 1 0 1 1 0 8 0 amappl13 176 49 0 46 1 0 1 1 0 8 0 amappl12 168 952 0 948 1 0 1 1 0 8 0 amappl11 160 36 0 27 1 0 1 1 0 8 0 amappl10 152 43 0 35 1 0 1 1 0 8 0 amappl9 144 234 0 234 2 2 0 1 0 8 0 amappl8 136 344 0 289 2 0 2 2 0 8 0 amappl7 128 66 0 56 1 0 1 1 0 8 0 amappl6 120 113 0 96 1 0 1 1 0 8 0 amappl5 112 125 0 118 1 0 1 1 0 8 0 amappl4 104 977 0 948 1 0 1 1 0 8 0 amappl3 96 1138 0 1122 1 0 1 1 0 8 0 amappl2 88 2678 0 2627 3 1 2 2 0 8 0 amappl1 80 29579 0 29173 14 5 9 12 0 8 0 amappl 88 18358 0 18171 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 128 253 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 17 0 10 1 0 1 1 0 8 0 uaddrrnd 24 1596 0 1580 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 1596 0 1580 1 0 1 1 0 8 0 vmmpekpl 168 12348 0 12328 3 1 2 2 0 8 0 vmmpepl 168 186247 0 183788 187 54 133 154 0 357 22 vmsppl 368 1595 0 1580 2 0 2 2 0 8 0 rwobjpl 56 35217 0 33442 28 2 26 26 0 8 0 pdppl 4096 3199 0 3160 63 22 41 45 0 8 2 pvpl 32 1043909 0 1012336 280 9 271 271 0 265 9 pmappl 232 1595 0 1580 2 1 1 2 0 8 0 extentpl 40 58 0 40 1 0 1 1 0 8 0 phpool 112 383 0 30 11 0 11 11 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:399 panic(ffffffff8246025e) at panic+0x177 sys/kern/subr_prf.c:202 knote_dequeue(fffffd806e8a4690) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000256ba9d0,fffffd806e8a4690) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9a9af8,ffff8000256ba9d0,ffff8000ffff5508) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9a9af8,ffff8000256ba9d0,ffff8000ffff5508) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff8000ffff5508,ffff8000256bac88,ffff8000256bacd0) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000256bad50) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000256bad50) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x9089f0f6400, count: -8 ddb{0}> machine ddbcpu 1 Stopped at x86_ipi_db+0x1a: addq $0x8,%rsp x86_ipi_db(ffff800020d58ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:353 x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23 end of kernel end trace frame: 0x7f7ffffe7cb0, count: 12 ddb{1}> trace x86_ipi_db(ffff800020d58ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:353 x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23 end of kernel end trace frame: 0x7f7ffffe7cb0, count: -3