panic: mutex 0xfffffd806e8b3438 not held in knote_dequeue Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 273047 97114 0 0 0x4000000 0 syz-executor.1 *329393 97114 0 0 0x4000000 1K syz-executor.1 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic(ffffffff82460c20) at panic+0x177 sys/kern/subr_prf.c:202 knote_dequeue(fffffd806e7b1ee0) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000222db560,fffffd806e7b1ee0) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e8b3438,ffff8000222db560,ffff800021273500) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e8b3438,ffff8000222db560,ffff800021273500) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff800021273500,ffff8000222db818,ffff8000222db860) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000222db8e0) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222db8e0) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x25b140aefc0, 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 0xfffffd806e8b3438 not held in knote_dequeue ddb{1}> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic(ffffffff82460c20) at panic+0x177 sys/kern/subr_prf.c:202 knote_dequeue(fffffd806e7b1ee0) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000222db560,fffffd806e7b1ee0) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e8b3438,ffff8000222db560,ffff800021273500) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e8b3438,ffff8000222db560,ffff800021273500) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff800021273500,ffff8000222db818,ffff8000222db860) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000222db8e0) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222db8e0) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x25b140aefc0, count: -8 ddb{1}> show registers rdi 0 rsi 0x1 rbp 0xffff8000222db350 rbx 0xffff800020d59bf7 rdx 0x8b rcx 0x2 rax 0x3a r8 0xffffffff816e1c04 kprintf+0x144 r9 0x1 r10 0xfe592468e2d509c1 r11 0xb3e75b3444706bbd r12 0xffff800020d599f8 r13 0 r14 0 r15 0x1 rip 0xffffffff81910f78 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff8000222db340 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb{1}> show proc PROC (syz-executor.1) pid=329393 stat=onproc flags process=0 proc=4000000 pri=32, usrpri=82, nice=20 forw=0xffffffffffffffff, list=0xffff800021272000,0xffffffff827da780 process=0xffff800021226a40 user=0xffff8000222d6000, vmspace=0xfffffd807f009a10 estcpu=36, cpticks=0, pctcpu=0.0 user=0, sys=0, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 2026 11873 77904 0 2 0 syz-executor.0 97114 194113 98531 0 2 0 syz-executor.1 97114 273047 98531 0 7 0x4000000 syz-executor.1 *97114 329393 98531 0 7 0x4000000 syz-executor.1 98531 344078 57586 0 3 0x82 nanoslp syz-executor.1 11581 41157 0 0 3 0x14200 acct acct 77904 405890 57586 0 3 0x82 nanoslp syz-executor.0 57586 215489 14877 0 3 0x82 thrsleep syz-fuzzer 57586 103925 14877 0 3 0x4000082 thrsleep syz-fuzzer 57586 58993 14877 0 3 0x4000082 kqread syz-fuzzer 57586 212258 14877 0 3 0x4000082 thrsleep syz-fuzzer 57586 453130 14877 0 3 0x4000082 thrsleep syz-fuzzer 57586 453458 14877 0 3 0x4000082 thrsleep syz-fuzzer 57586 343600 14877 0 3 0x4000082 thrsleep syz-fuzzer 57586 77197 14877 0 3 0x4000082 thrsleep syz-fuzzer 14877 125450 3818 0 3 0x10008a sigsusp ksh 3818 62534 70369 0 3 0x92 select sshd 10175 350149 1 0 3 0x100083 ttyin getty 70369 58803 1 0 3 0x80 select sshd 48021 306340 9649 74 3 0x100092 bpf pflogd 9649 54626 1 0 3 0x80 netio pflogd 78490 226928 1314 73 3 0x100090 kqread syslogd 1314 519135 1 0 3 0x100082 netio syslogd 99506 93647 1 77 3 0x100090 poll dhclient 85681 248642 1 0 3 0x80 poll dhclient 77458 504266 0 0 3 0x14200 bored smr 55680 317030 0 0 2 0x14200 zerothread 42926 461518 0 0 3 0x14200 aiodoned aiodoned 31365 330839 0 0 3 0x14200 syncer update 98048 335622 0 0 3 0x14200 cleaner cleaner 46148 326989 0 0 3 0x14200 reaper reaper 43142 205794 0 0 3 0x14200 pgdaemon pagedaemon 5016 207919 0 0 3 0x14200 bored crynlk 10736 150050 0 0 3 0x14200 bored crypto 10939 326311 0 0 3 0x14200 bored viomb 37533 3272 0 0 3 0x40014200 acpi0 acpi0 6114 137233 0 0 3 0x40014200 idle1 85459 471004 0 0 3 0x14200 bored softnet 59315 428920 0 0 3 0x14200 bored systqmp 53224 73602 0 0 3 0x14200 bored systq 21690 328499 0 0 3 0x40014200 bored softclock 63428 149037 0 0 3 0x40014200 idle0 1 147543 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{1}> show all locks Process 97114 (syz-executor.1) thread 0xffff800021273500 (329393) exclusive kernel_lock &kernel_lock r = 1 (0xffffffff827d4278) #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 10131 6486K 6678K 78643K 17678 0 pcb 13 8K 8K 78643K 409 0 rtable 105 3K 3K 78643K 237 0 ifaddr 44 10K 10K 78643K 52 0 counters 44 34K 34K 78643K 46 0 ioctlops 0 0K 4K 78643K 2109 0 iov 0 0K 12K 78643K 839 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 1 0 vnodes 1219 77K 77K 78643K 4377 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 9K 78643K 275 0 VM map 2 1K 1K 78643K 2 0 sem 12 0K 0K 78643K 321 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12598 0 file desc 6 17K 25K 78643K 34384 0 sigio 0 0K 0K 78643K 65 0 proc 60 63K 95K 78643K 478 0 subproc 32 2K 2K 78643K 51 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 in_multi 33 2K 2K 78643K 44 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 43 201K 201K 78643K 43 0 exec 0 0K 2K 78643K 378 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 227 27K 27K 78643K 408637 0 UVM aobj 131 4K 4K 78643K 152 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 NDP 6 0K 0K 78643K 13 0 temp 105 3985K 4049K 78643K 81017 0 kqueue 6 7K 9K 78643K 909 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 21 0 19 1 0 1 1 0 8 0 rtentry 112 56 0 12 2 0 2 2 0 8 0 unpcb 120 9653 0 9643 1 0 1 1 0 8 0 syncache 296 4 0 4 1 1 0 1 0 8 0 tcpcb 736 95 0 91 5 4 1 3 0 8 0 arp 120 8 0 2 1 0 1 1 0 8 0 inpcb 304 1610 0 1604 1 0 1 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 pffrag 232 6 0 6 1 1 0 1 0 482 0 pffrnode 88 4 0 4 1 1 0 1 0 8 0 pffrent 40 152 0 152 1 1 0 1 0 8 0 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 17 0 15 1 0 1 1 0 8 0 pfstkey 112 17 0 15 1 0 1 1 0 8 0 pfstate 320 17 0 15 1 0 1 1 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 256 233 0 44 12 0 12 12 0 8 0 art_table 32 234 0 44 2 0 2 2 0 8 0 art_node 16 55 0 15 1 0 1 1 0 8 0 semapl 112 319 0 309 1 0 1 1 0 8 0 shmpl 112 149 0 21 4 0 4 4 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 40522 0 39117 90 1 89 89 0 8 0 ffsino 272 40522 0 39117 96 2 94 95 0 8 0 nchpl 144 83641 0 82038 76 15 61 61 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 208762 0 208762 3 2 1 1 0 8 1 percpumem 16 35 0 1 1 0 1 1 0 8 0 scxspl 216 234507 0 234507 10 9 1 8 0 8 1 plimitpl 152 16 0 8 1 0 1 1 0 8 0 sigapl 424 34609 0 34575 4 0 4 4 0 8 0 futexpl 56 130989 0 130989 11 10 1 1 0 8 1 knotepl 112 40 0 0 2 0 2 2 0 8 0 kqueuepl 216 2378 0 2374 1 0 1 1 0 8 0 pipepl 336 80 0 69 2 0 2 2 0 8 0 fdescpl 496 34580 0 34563 3 0 3 3 0 8 0 filepl 152 89116 0 89011 31 26 5 5 0 8 0 lockfpl 104 1674 0 1673 1 0 1 1 0 8 0 lockfspl 48 745 0 744 1 0 1 1 0 8 0 sessionpl 144 19 0 8 1 0 1 1 0 8 0 pgrppl 48 306 0 295 1 0 1 1 0 8 0 ucredpl 96 2986 0 2977 1 0 1 1 0 8 0 zombiepl 144 34575 0 34575 1 0 1 1 0 8 1 processpl 1080 34609 0 34575 3 0 3 3 0 8 0 procpl 672 74294 0 74251 5 1 4 5 0 8 0 sockpl 480 11284 0 11266 13 9 4 4 0 8 1 mcl64k 65536 26 0 0 4 1 3 3 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 28 0 0 2 0 2 2 0 8 0 mcl8k 8192 30 0 0 4 1 3 3 0 8 0 mcl4k 4096 38 0 0 3 0 3 3 0 8 0 mcl2k2 2112 15 0 0 1 0 1 1 0 8 0 mcl2k 2048 155 0 0 10 0 10 10 0 8 0 mtagpl 96 1 0 0 1 0 1 1 0 8 0 mbufpl 256 1144 0 0 20 4 16 17 0 8 1 bufpl 280 41548 0 35228 452 0 452 452 0 8 0 anonpl 24 8699778 0 8693094 92 26 66 66 0 186 24 amapchunkpl 152 967463 0 967073 36 19 17 17 0 158 2 amappl16 200 66043 0 65884 24 2 22 22 0 8 13 amappl15 192 64 0 57 1 0 1 1 0 8 0 amappl14 184 3 0 2 1 0 1 1 0 8 0 amappl13 176 16405 0 16404 1 0 1 1 0 8 0 amappl12 168 6 0 6 2 2 0 1 0 8 0 amappl11 160 17247 0 17233 1 0 1 1 0 8 0 amappl10 152 809 0 796 1 0 1 1 0 8 0 amappl9 144 241 0 240 1 0 1 1 0 8 0 amappl8 136 731 0 640 4 0 4 4 0 8 0 amappl7 128 69 0 61 1 0 1 1 0 8 0 amappl6 120 125 0 106 1 0 1 1 0 8 0 amappl5 112 36125 0 36110 1 0 1 1 0 8 0 amappl4 104 17938 0 17906 1 0 1 1 0 8 0 amappl3 96 1356 0 1345 1 0 1 1 0 8 0 amappl2 88 51793 0 51748 6 4 2 2 0 8 0 amappl1 80 522909 0 522477 14 4 10 12 0 8 0 amappl 88 408293 0 408165 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 64 151 0 21 3 0 3 3 0 8 0 uaddrrnd 24 34580 0 34563 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 34580 0 34563 1 0 1 1 0 8 0 vmmpekpl 168 116578 0 116551 2 0 2 2 0 8 0 vmmpepl 168 3814819 0 3813286 114 35 79 79 0 357 11 vmsppl 368 34579 0 34563 2 0 2 2 0 8 0 rwobjpl 56 625280 0 624390 22 5 17 17 0 8 4 pdppl 4096 69167 0 69126 59 18 41 45 0 8 0 pvpl 32 14532050 0 14521997 297 180 117 132 0 265 35 pmappl 232 34579 0 34563 2 1 1 2 0 8 0 extentpl 40 58 0 40 1 0 1 1 0 8 0 phpool 112 322 0 36 9 0 9 9 0 8 0 ddb{1}> machine ddbcpu 0 Stopped at x86_ipi_db+0x1a: addq $0x8,%rsp x86_ipi_db(ffffffff8275cff0) 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 __mp_lock(ffffffff827d4070) at __mp_lock+0x129 __mp_lock_spin sys/kern/kern_lock.c:116 [inline] __mp_lock(ffffffff827d4070) at __mp_lock+0x129 sys/kern/kern_lock.c:147 sys_futex(ffff800021272d20,ffff8000222cef40,ffff8000222cef90) at sys_futex+0xfb sys/kern/sys_futex.c:110 syscall(ffff8000222cf010) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222cf010) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x25b1a0c3af0, count: 8 ddb{0}> trace x86_ipi_db(ffffffff8275cff0) 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 __mp_lock(ffffffff827d4070) at __mp_lock+0x129 __mp_lock_spin sys/kern/kern_lock.c:116 [inline] __mp_lock(ffffffff827d4070) at __mp_lock+0x129 sys/kern/kern_lock.c:147 sys_futex(ffff800021272d20,ffff8000222cef40,ffff8000222cef90) at sys_futex+0xfb sys/kern/sys_futex.c:110 syscall(ffff8000222cf010) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222cf010) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x25b1a0c3af0, count: -7 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(ffffffff82460c20) at panic+0x177 sys/kern/subr_prf.c:202 knote_dequeue(fffffd806e7b1ee0) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000222db560,fffffd806e7b1ee0) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e8b3438,ffff8000222db560,ffff800021273500) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e8b3438,ffff8000222db560,ffff800021273500) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff800021273500,ffff8000222db818,ffff8000222db860) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000222db8e0) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222db8e0) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x25b140aefc0, count: 7 ddb{1}> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic(ffffffff82460c20) at panic+0x177 sys/kern/subr_prf.c:202 knote_dequeue(fffffd806e7b1ee0) at knote_dequeue+0x12b sys/kern/kern_event.c:1860 filt_timermodify(ffff8000222db560,fffffd806e7b1ee0) at filt_timermodify+0x6f sys/kern/kern_event.c:479 kqueue_register(fffffd806e8b3438,ffff8000222db560,ffff800021273500) at kqueue_register+0xa89 filter_modify sys/kern/kern_event.c:662 [inline] kqueue_register(fffffd806e8b3438,ffff8000222db560,ffff800021273500) at kqueue_register+0xa89 sys/kern/kern_event.c:1125 sys_kevent(ffff800021273500,ffff8000222db818,ffff8000222db860) at sys_kevent+0x214 sys/kern/kern_event.c:887 syscall(ffff8000222db8e0) at syscall+0x5bf mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff8000222db8e0) at syscall+0x5bf sys/arch/amd64/amd64/trap.c:587 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x25b140aefc0, count: -8