panic: mutex 0xfffffd806e9a8a20 not held in knote_dequeue Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 29064 74811 32767 0x10 0 0 syz-executor.1 * 86867 74811 32767 0x10 0x4000000 1K syz-executor.1 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(fffffd806e8a4460) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000256d6600,fffffd806e8a4460) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9a8a20,ffff8000256d6600,ffff80002129dce8) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9a8a20,ffff8000256d6600,ffff80002129dce8) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff80002129dce8,ffff8000256d6818,ffff8000256d6860) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000256d68e0) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000256d68e0) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xa1636a0d1f0, 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{1}> ddb{1}> set $lines = 0 ddb{1}> set $maxwidth = 0 ddb{1}> show panic *cpu1: mutex 0xfffffd806e9a8a20 not held in knote_dequeue ddb{1}> 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(fffffd806e8a4460) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000256d6600,fffffd806e8a4460) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9a8a20,ffff8000256d6600,ffff80002129dce8) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9a8a20,ffff8000256d6600,ffff80002129dce8) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff80002129dce8,ffff8000256d6818,ffff8000256d6860) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000256d68e0) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000256d68e0) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xa1636a0d1f0, count: -8 ddb{1}> show registers rdi 0 rsi 0x1 rbp 0xffff8000256d6350 rbx 0xffff800020d59bf7 rdx 0x8b rcx 0x2 rax 0x3a r8 0xffffffff81bb3f14 kprintf+0x144 r9 0x1 r10 0x7e93a7c10975f0f4 r11 0x432975a8070b1a12 r12 0xffff800020d599f8 r13 0 r14 0 r15 0x1 rip 0xffffffff81b43698 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff8000256d6340 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb{1}> show proc PROC (syz-executor.1) pid=86867 stat=onproc flags process=10 proc=4000000 pri=32, usrpri=80, nice=20 forw=0xffffffffffffffff, list=0xffff80002129da48,0xffff80002129d278 process=0xffff8000ffff1970 user=0xffff8000256d1000, vmspace=0xfffffd807f009730 estcpu=36, cpticks=0, pctcpu=0.0 user=0, sys=0, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 70783 367079 42426 32767 2 0x10 syz-executor.0 74811 29064 69021 32767 7 0x10 syz-executor.1 *74811 86867 69021 32767 7 0x4000010 syz-executor.1 42426 400541 2619 32767 3 0x90 nanoslp syz-executor.0 2619 68678 12161 0 3 0x82 wait syz-executor.0 69021 190383 73925 32767 3 0x90 nanoslp syz-executor.1 73925 6693 12161 0 3 0x82 wait syz-executor.1 68570 3309 0 0 3 0x14200 bored sosplice 12161 380057 56241 0 3 0x82 thrsleep syz-fuzzer 12161 203471 56241 0 3 0x4000082 nanoslp syz-fuzzer 12161 194020 56241 0 3 0x4000082 thrsleep syz-fuzzer 12161 371080 56241 0 3 0x4000082 thrsleep syz-fuzzer 12161 204734 56241 0 3 0x4000082 thrsleep syz-fuzzer 12161 129278 56241 0 3 0x4000082 kqread syz-fuzzer 12161 58423 56241 0 3 0x4000082 thrsleep syz-fuzzer 12161 28252 56241 0 3 0x4000082 thrsleep syz-fuzzer 56241 191328 37144 0 3 0x10008a sigsusp ksh 37144 264597 65753 0 3 0x92 select sshd 73854 949 1 0 3 0x100083 ttyin getty 65753 460494 1 0 3 0x80 select sshd 25164 402705 54401 73 3 0x100090 kqread syslogd 54401 168590 1 0 3 0x100082 netio syslogd 77479 196738 1 77 3 0x100090 poll dhclient 46783 276342 1 0 3 0x80 poll dhclient 18225 473932 0 0 3 0x14200 bored smr 22912 510543 0 0 2 0x14200 zerothread 64048 31313 0 0 3 0x14200 aiodoned aiodoned 44499 33877 0 0 3 0x14200 syncer update 74909 305274 0 0 3 0x14200 cleaner cleaner 85536 451379 0 0 3 0x14200 reaper reaper 59259 240063 0 0 3 0x14200 pgdaemon pagedaemon 17442 436240 0 0 3 0x14200 bored crynlk 85621 229333 0 0 3 0x14200 bored crypto 6479 151901 0 0 3 0x14200 bored viomb 55333 310672 0 0 3 0x40014200 acpi0 acpi0 30650 400643 0 0 3 0x40014200 idle1 89655 275124 0 0 3 0x14200 bored softnet 39594 513486 0 0 3 0x14200 bored systqmp 51130 48162 0 0 3 0x14200 bored systq 18858 395077 0 0 3 0x40014200 bored softclock 41296 20714 0 0 3 0x40014200 idle0 1 220801 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{1}> show all locks Process 74811 (syz-executor.1) thread 0xffff80002129dce8 (86867) 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{1}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10119 6414K 6414K 78643K 11215 0 pcb 13 8K 8K 78643K 13 0 rtable 109 3K 3K 78643K 304 0 ifaddr 39 10K 10K 78643K 53 0 sysctl 3 1K 1K 78643K 3 0 counters 44 34K 34K 78643K 48 0 ioctlops 0 0K 2K 78643K 53 0 iov 0 0K 12K 78643K 47 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 1 0 vnodes 1216 76K 76K 78643K 1313 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 5K 78643K 4 0 VM map 2 1K 1K 78643K 2 0 sem 12 0K 1K 78643K 1812 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12598 0 file desc 8 25K 33K 78643K 2159 0 sigio 0 0K 0K 78643K 4 0 proc 48 50K 83K 78643K 501 0 subproc 34 2K 2K 78643K 68 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 ip_moptions 0 0K 0K 78643K 112 0 in_multi 33 2K 2K 78643K 80 0 ether_multi 1 0K 0K 78643K 6 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 494 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 261 34K 41K 78643K 28163 0 UVM aobj 29 2K 2K 78643K 36 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 40 0 NDP 5 0K 0K 78643K 15 0 temp 101 3985K 4049K 78643K 6424 0 kqueue 7 5K 10K 78643K 77 0 SYN cache 2 16K 16K 78643K 2 0 ddb{1}> 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 78 0 76 1 0 1 1 0 8 0 rtentry 112 71 0 25 2 0 2 2 0 8 0 unpcb 120 754 0 744 1 0 1 1 0 8 0 syncache 296 17 0 17 4 4 0 1 0 8 0 sackhl 24 2 0 2 1 0 1 1 0 8 1 tcpqe 32 526 0 526 4 4 0 1 0 8 0 tcpcb 736 350 0 342 3 0 3 3 0 8 0 arp 120 10 0 4 1 0 1 1 0 8 0 ipq 40 3 0 3 2 2 0 1 0 8 0 ipqe 40 51 0 51 2 2 0 1 0 8 0 inpcb 304 706 0 699 2 0 2 2 0 8 1 ip6q 72 3 0 2 2 1 1 1 0 8 0 ip6af 40 4 0 4 2 2 0 1 0 8 0 nd6 48 16 0 8 1 0 1 1 0 8 0 kcovpl 48 4 0 2 1 0 1 1 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 296 0 103 13 0 13 13 0 8 0 art_table 32 297 0 103 2 0 2 2 0 8 0 art_node 16 70 0 28 1 0 1 1 0 8 0 sysvmsgpl 40 32 0 12 1 0 1 1 0 8 0 semupl 112 4 0 4 1 1 0 1 0 8 0 semapl 112 1802 0 1792 1 0 1 1 0 8 0 shmpl 112 33 0 7 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 3836 0 2434 88 0 88 88 0 8 0 ffsino 272 3836 0 2434 94 0 94 94 0 8 0 nchpl 144 7054 0 5458 60 0 60 60 0 8 0 uvmvnodes 72 3913 0 0 72 0 72 72 0 8 0 vnodes 224 3913 0 0 231 0 231 231 0 8 0 namei 1024 16471 0 16471 2 1 1 1 0 8 1 percpumem 16 36 0 2 1 0 1 1 0 8 0 scxspl 216 18730 0 18730 10 9 1 8 0 8 1 plimitpl 152 68 0 59 1 0 1 1 0 8 0 sigapl 424 2341 0 2307 4 0 4 4 0 8 0 futexpl 56 32876 0 32876 1 0 1 1 0 8 1 knotepl 112 38 0 0 2 0 2 2 0 8 0 kqueuepl 216 3316 0 3312 1 0 1 1 0 8 0 pipepl 336 242 0 231 3 1 2 2 0 8 0 fdescpl 496 2324 0 2307 3 0 3 3 0 8 0 filepl 152 10525 0 10426 6 1 5 5 0 8 1 lockfpl 104 338 0 336 1 0 1 1 0 8 0 lockfspl 48 125 0 123 1 0 1 1 0 8 0 sessionpl 144 19 0 9 1 0 1 1 0 8 0 pgrppl 48 19 0 9 1 0 1 1 0 8 0 ucredpl 96 927 0 918 1 0 1 1 0 8 0 zombiepl 144 2307 0 2307 2 1 1 1 0 8 1 processpl 1080 2341 0 2307 5 2 3 3 0 8 0 procpl 672 5349 0 5307 6 2 4 5 0 8 0 sosppl 168 13 0 13 3 3 0 1 0 8 0 sockpl 480 1552 0 1533 4 0 4 4 0 8 0 mcl64k 65536 13 0 0 2 0 2 2 0 8 0 mcl16k 16384 15 0 0 2 0 2 2 0 8 0 mcl12k 12288 17 0 0 2 0 2 2 0 8 0 mcl9k 9216 4 0 0 1 0 1 1 0 8 0 mcl8k 8192 16 0 0 2 0 2 2 0 8 0 mcl4k 4096 17 0 0 3 0 3 3 0 8 0 mcl2k2 2112 7 0 0 1 0 1 1 0 8 0 mcl2k 2048 336 0 0 41 0 41 41 0 8 0 mtagpl 96 1 0 0 1 0 1 1 0 8 0 mbufpl 256 1006 0 0 62 0 62 62 0 8 0 bufpl 280 5671 0 145 395 0 395 395 0 8 0 anonpl 24 643535 0 612952 213 18 195 208 0 186 3 amapchunkpl 152 65855 0 65024 38 4 34 38 0 158 0 amappl16 200 5624 0 4337 84 14 70 81 0 8 2 amappl15 192 62 0 54 1 0 1 1 0 8 0 amappl14 184 432 0 431 2 1 1 1 0 8 0 amappl13 176 78 0 75 1 0 1 1 0 8 0 amappl12 168 684 0 682 1 0 1 1 0 8 0 amappl11 160 41 0 31 1 0 1 1 0 8 0 amappl10 152 53 0 46 1 0 1 1 0 8 0 amappl9 144 605 0 602 1 0 1 1 0 8 0 amappl8 136 1017 0 956 3 0 3 3 0 8 0 amappl7 128 714 0 704 1 0 1 1 0 8 0 amappl6 120 483 0 464 1 0 1 1 0 8 0 amappl5 112 1144 0 1134 1 0 1 1 0 8 0 amappl4 104 1006 0 977 1 0 1 1 0 8 0 amappl3 96 946 0 938 1 0 1 1 0 8 0 amappl2 88 3191 0 3144 3 1 2 2 0 8 0 amappl1 80 41256 0 40851 14 5 9 12 0 8 0 amappl 88 27179 0 26992 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 35 0 7 1 0 1 1 0 8 0 uaddrrnd 24 2324 0 2307 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 2324 0 2307 1 0 1 1 0 8 0 vmmpekpl 168 16992 0 16965 2 0 2 2 0 8 0 vmmpepl 168 272868 0 270133 213 55 158 173 0 357 38 vmsppl 368 2323 0 2307 2 0 2 2 0 8 0 rwobjpl 56 50226 0 48236 33 4 29 32 0 8 0 pdppl 4096 4655 0 4614 62 21 41 45 0 8 0 pvpl 32 1566313 0 1532226 325 27 298 310 0 265 15 pmappl 232 2323 0 2307 2 1 1 2 0 8 0 extentpl 40 58 0 40 1 0 1 1 0 8 0 phpool 112 386 0 25 11 0 11 11 0 8 0 ddb{1}> machine ddbcpu 0 Stopped at x86_ipi_db+0x1a: addq $0x8,%rsp x86_ipi_db(ffffffff82709ff0) 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: 0x7f7ffffdf660, count: 12 ddb{0}> trace x86_ipi_db(ffffffff82709ff0) 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: 0x7f7ffffdf660, count: -3 ddb{0}> machine ddbcpu 1 Stopped at db_enter+0x18: addq $0x8,%rsp 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(fffffd806e8a4460) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000256d6600,fffffd806e8a4460) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9a8a20,ffff8000256d6600,ffff80002129dce8) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9a8a20,ffff8000256d6600,ffff80002129dce8) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff80002129dce8,ffff8000256d6818,ffff8000256d6860) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000256d68e0) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000256d68e0) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xa1636a0d1f0, count: 7 ddb{1}> 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(fffffd806e8a4460) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000256d6600,fffffd806e8a4460) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9a8a20,ffff8000256d6600,ffff80002129dce8) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9a8a20,ffff8000256d6600,ffff80002129dce8) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff80002129dce8,ffff8000256d6818,ffff8000256d6860) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000256d68e0) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000256d68e0) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xa1636a0d1f0, count: -8