panic: mutex 0xfffffd806e9aa948 not held in knote_dequeue Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *486006 98803 32767 0x10 0x4000000 0K syz-executor.1 394364 39334 32767 0x10 0 1 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(fffffd806e8a5d20) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000234a6a90,fffffd806e8a5d20) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9aa948,ffff8000234a6a90,ffff8000ffff47e0) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9aa948,ffff8000234a6a90,ffff8000ffff47e0) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff8000ffff47e0,ffff8000234a6ca8,ffff8000234a6cf0) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000234a6d70) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000234a6d70) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7274b78dde0, 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 0xfffffd806e9aa948 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(fffffd806e8a5d20) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000234a6a90,fffffd806e8a5d20) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9aa948,ffff8000234a6a90,ffff8000ffff47e0) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9aa948,ffff8000234a6a90,ffff8000ffff47e0) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff8000ffff47e0,ffff8000234a6ca8,ffff8000234a6cf0) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000234a6d70) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000234a6d70) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7274b78dde0, count: -8 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff8000234a67e0 rbx 0xffffffff8270abf7 cpu_info_full_primary+0x2bf7 rdx 0x8b rcx 0x2 rax 0x3a r8 0xffffffff81bb3f14 kprintf+0x144 r9 0x1 r10 0xb0b8b1a583bc9a11 r11 0x6e85f4b0469cbeb0 r12 0xffffffff8270a9f8 cpu_info_full_primary+0x29f8 r13 0 r14 0 r15 0x1 rip 0xffffffff81b43698 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff8000234a67d0 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor.1) pid=486006 stat=onproc flags process=10 proc=4000000 pri=86, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff8000ffff4d20,0xffffffff828f5570 process=0xffff8000ffff2610 user=0xffff8000234a1000, vmspace=0xfffffd807f009730 estcpu=36, cpticks=0, pctcpu=0.0 user=0, sys=0, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 98803 495233 40322 32767 2 0x10 syz-executor.1 98803 457684 40322 32767 3 0x4000090 kqread syz-executor.1 *98803 486006 40322 32767 7 0x4000010 syz-executor.1 8077 333517 0 0 3 0x14200 bored sosplice 40322 253242 10355 32767 3 0x90 nanoslp syz-executor.1 39334 394364 57451 32767 7 0x10 syz-executor.0 10355 36186 47391 0 3 0x82 wait syz-executor.1 57451 34306 47391 0 3 0x82 wait syz-executor.0 47391 27385 21182 0 3 0x82 thrsleep syz-fuzzer 47391 398363 21182 0 3 0x4000082 nanoslp syz-fuzzer 47391 198426 21182 0 3 0x4000082 thrsleep syz-fuzzer 47391 464383 21182 0 3 0x4000082 thrsleep syz-fuzzer 47391 111165 21182 0 3 0x4000082 kqread syz-fuzzer 47391 269723 21182 0 3 0x4000082 thrsleep syz-fuzzer 47391 193290 21182 0 3 0x4000082 thrsleep syz-fuzzer 47391 20504 21182 0 3 0x4000082 thrsleep syz-fuzzer 21182 98086 50627 0 3 0x10008a sigsusp ksh 50627 228999 90405 0 3 0x92 select sshd 46889 395217 1 0 3 0x100083 ttyin getty 90405 201679 1 0 3 0x80 select sshd 85292 489893 1859 73 3 0x100090 kqread syslogd 1859 486519 1 0 3 0x100082 netio syslogd 64097 123243 1 77 3 0x100090 poll dhclient 86972 283626 1 0 3 0x80 poll dhclient 37521 183533 0 0 3 0x14200 bored smr 75757 392727 0 0 2 0x14200 zerothread 8929 372574 0 0 3 0x14200 aiodoned aiodoned 48517 17710 0 0 3 0x14200 syncer update 20875 501614 0 0 3 0x14200 cleaner cleaner 54103 326733 0 0 3 0x14200 reaper reaper 88147 244977 0 0 3 0x14200 pgdaemon pagedaemon 9910 415791 0 0 3 0x14200 bored crynlk 13184 192680 0 0 3 0x14200 bored crypto 79242 47454 0 0 3 0x14200 bored viomb 49601 413745 0 0 3 0x40014200 acpi0 acpi0 81451 330464 0 0 3 0x40014200 idle1 75713 506981 0 0 3 0x14200 bored softnet 43087 450101 0 0 3 0x14200 bored systqmp 60888 27244 0 0 3 0x14200 bored systq 68476 227793 0 0 3 0x40014200 bored softclock 36219 301635 0 0 3 0x40014200 idle0 1 315989 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{0}> show all locks Process 98803 (syz-executor.1) thread 0xffff8000ffff47e0 (486006) 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 10117 6414K 6414K 78643K 11207 0 pcb 13 8K 8K 78643K 13 0 rtable 107 3K 3K 78643K 221 0 ifaddr 39 10K 10K 78643K 39 0 counters 44 34K 34K 78643K 44 0 ioctlops 0 0K 2K 78643K 37 0 iov 0 0K 24K 78643K 35 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 1 0 vnodes 1216 76K 77K 78643K 1277 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 10 1K 1K 78643K 12 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12598 0 file desc 7 21K 33K 78643K 1855 0 sigio 0 0K 0K 78643K 14 0 proc 48 50K 70K 78643K 438 0 subproc 34 2K 2K 78643K 34 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 ip_moptions 0 0K 0K 78643K 293 0 in_multi 33 2K 2K 78643K 92 0 ether_multi 1 0K 0K 78643K 11 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 43 201K 201K 78643K 43 0 exec 0 0K 2K 78643K 426 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 199 28K 58K 78643K 23745 0 UVM aobj 19 2K 2K 78643K 19 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 47 0 NDP 5 0K 0K 78643K 9 0 temp 101 3985K 4049K 78643K 5606 0 kqueue 5 5K 9K 78643K 104 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 68 0 66 1 0 1 1 0 8 0 rtentry 112 47 0 2 2 0 2 2 0 8 0 unpcb 120 717 0 709 1 0 1 1 0 8 0 syncache 296 19 0 19 4 3 1 1 0 8 1 tcpqe 32 101 0 101 5 4 1 1 0 8 1 tcpcb 736 540 0 535 12 6 6 7 0 8 5 arp 120 6 0 0 1 0 1 1 0 8 0 inpcb 304 919 0 912 4 2 2 2 0 8 1 nd6 48 8 0 1 1 0 1 1 0 8 0 kcovpl 48 2 0 0 1 0 1 1 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 193 0 2 12 0 12 12 0 8 0 art_table 32 194 0 2 2 0 2 2 0 8 0 art_node 16 46 0 5 1 0 1 1 0 8 0 sysvmsgpl 40 39 0 12 1 0 1 1 0 8 0 semupl 112 6 0 6 1 1 0 1 0 8 0 semapl 112 8 0 0 1 0 1 1 0 8 0 shmpl 112 16 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 3576 0 2178 88 0 88 88 0 8 0 ffsino 272 3576 0 2178 94 0 94 94 0 8 0 nchpl 144 6194 0 4586 60 0 60 60 0 8 0 uvmvnodes 72 3619 0 0 66 0 66 66 0 8 0 vnodes 224 3619 0 0 213 0 213 213 0 8 0 namei 1024 14002 0 14002 2 1 1 1 0 8 1 percpumem 16 34 0 0 1 0 1 1 0 8 0 scxspl 216 17278 0 17278 9 8 1 8 0 8 1 plimitpl 152 94 0 85 1 0 1 1 0 8 0 sigapl 424 2043 0 2010 4 0 4 4 0 8 0 futexpl 56 22627 0 22627 2 1 1 1 0 8 1 knotepl 112 35 0 0 1 0 1 1 0 8 0 kqueuepl 216 1647 0 1643 1 0 1 1 0 8 0 pipepl 336 208 0 197 5 3 2 2 0 8 1 fdescpl 496 2026 0 2010 3 0 3 3 0 8 0 filepl 152 7669 0 7569 6 1 5 5 0 8 1 lockfpl 104 207 0 206 1 0 1 1 0 8 0 lockfspl 48 90 0 89 1 0 1 1 0 8 0 sessionpl 144 17 0 7 1 0 1 1 0 8 0 pgrppl 48 55 0 45 1 0 1 1 0 8 0 ucredpl 96 552 0 543 1 0 1 1 0 8 0 zombiepl 144 2010 0 2010 1 0 1 1 0 8 1 processpl 1080 2043 0 2010 4 1 3 3 0 8 0 procpl 672 4224 0 4182 4 0 4 4 0 8 0 sockpl 480 1704 0 1687 6 3 3 4 0 8 0 mcl64k 65536 6 0 0 1 0 1 1 0 8 0 mcl16k 16384 17 0 0 3 0 3 3 0 8 0 mcl12k 12288 25 0 0 2 0 2 2 0 8 0 mcl9k 9216 4 0 0 1 0 1 1 0 8 0 mcl8k 8192 12 0 0 2 0 2 2 0 8 0 mcl4k 4096 17 0 0 3 0 3 3 0 8 0 mcl2k2 2112 2 0 0 1 0 1 1 0 8 0 mcl2k 2048 193 0 0 21 0 21 21 0 8 0 mtagpl 96 1 0 0 1 0 1 1 0 8 0 mbufpl 256 670 0 0 40 0 40 40 0 8 0 bufpl 280 5795 0 144 404 0 404 404 0 8 0 anonpl 24 503684 0 495947 55 6 49 49 0 186 1 amapchunkpl 152 60948 0 60544 41 3 38 38 0 158 21 amappl16 200 3518 0 3316 13 2 11 11 0 8 0 amappl15 192 54 0 48 1 0 1 1 0 8 0 amappl14 184 899 0 895 1 0 1 1 0 8 0 amappl13 176 44 0 43 1 0 1 1 0 8 0 amappl12 168 6 0 4 1 0 1 1 0 8 0 amappl11 160 35 0 26 1 0 1 1 0 8 0 amappl10 152 42 0 33 1 0 1 1 0 8 0 amappl9 144 960 0 957 1 0 1 1 0 8 0 amappl8 136 372 0 302 3 0 3 3 0 8 0 amappl7 128 60 0 52 1 0 1 1 0 8 0 amappl6 120 1052 0 1036 1 0 1 1 0 8 0 amappl5 112 1540 0 1531 1 0 1 1 0 8 0 amappl4 104 1433 0 1402 1 0 1 1 0 8 0 amappl3 96 264 0 255 1 0 1 1 0 8 0 amappl2 88 2188 0 2144 4 2 2 2 0 8 1 amappl1 80 35539 0 35127 12 3 9 12 0 8 0 amappl 88 23035 0 22914 4 0 4 4 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 18 0 0 1 0 1 1 0 8 0 uaddrrnd 24 2026 0 2010 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 2026 0 2010 1 0 1 1 0 8 0 vmmpekpl 168 13240 0 13220 2 0 2 2 0 8 0 vmmpepl 168 230656 0 229105 75 2 73 73 0 357 1 vmsppl 368 2025 0 2010 2 0 2 2 0 8 0 rwobjpl 56 40944 0 40072 15 2 13 13 0 8 0 pdppl 4096 4059 0 4020 57 16 41 45 0 8 2 pvpl 32 1165408 0 1154322 149 52 97 129 0 265 4 pmappl 232 2025 0 2010 2 1 1 2 0 8 0 extentpl 40 58 0 40 1 0 1 1 0 8 0 phpool 112 349 0 28 10 0 10 10 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(fffffd806e8a5d20) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000234a6a90,fffffd806e8a5d20) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e9aa948,ffff8000234a6a90,ffff8000ffff47e0) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e9aa948,ffff8000234a6a90,ffff8000ffff47e0) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff8000ffff47e0,ffff8000234a6ca8,ffff8000234a6cf0) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000234a6d70) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000234a6d70) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7274b78dde0, 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 __sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc syscall(ffff800021298da0) at syscall+0x439 mi_syscall sys/sys/syscall_mi.h:93 [inline] syscall(ffff800021298da0) at syscall+0x439 sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffbe450, count: 9 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 __sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc syscall(ffff800021298da0) at syscall+0x439 mi_syscall sys/sys/syscall_mi.h:93 [inline] syscall(ffff800021298da0) at syscall+0x439 sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffbe450, count: -6