witness: lock order reversal: 1st 0xffffffff82cfb918 &sched_lock (&sched_lock) 2nd 0xffff80002e46cdc0 &pr->ps_mtx (&pr->ps_mtx) lock order "&pr->ps_mtx"(mutex) -> "&sched_lock"(sched_lock) first seen at: #0 __mp_lock+0xa2 read_rflags machine/cpufunc.h:195 [inline] #0 __mp_lock+0xa2 intr_disable machine/cpufunc.h:216 [inline] #0 __mp_lock+0xa2 sys/kern/kern_lock.c:142 #1 donice+0x178 sys/kern/kern_resource.c:218 #2 syscall+0x5e2 mi_syscall sys/sys/syscall_mi.h:110 [inline] #2 syscall+0x5e2 sys/arch/amd64/amd64/trap.c:623 #3 Xsyscall+0x128 lock order "&sched_lock"(sched_lock) -> "&pr->ps_mtx"(mutex) first seen at: #0 mtx_enter+0x3e sys/kern/kern_lock.c:265 #1 single_thread_set+0x35a single_thread_wait sys/kern/kern_sig.c:2172 [inline] #1 single_thread_set+0x35a sys/kern/kern_sig.c:2155 #2 sigexit+0x90 sys/kern/kern_sig.c:1562 #3 postsig+0x4a9 sys/kern/kern_sig.c:1494 #4 userret+0x16e sys/kern/kern_sig.c:1987 #5 syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] #5 syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 #6 Xsyscall+0x128 Stopped at db_enter+0x1c: addq $0x8,%rsp ddb{1}> ddb{1}> set $lines = 0 ddb{1}> set $maxwidth = 0 ddb{1}> show panic the kernel did not panic ddb{1}> trace db_enter() at db_enter+0x1c sys/arch/amd64/amd64/db_interface.c:437 witness_checkorder(ffff80002e46cdc0,9,0) at witness_checkorder+0x10b7 witness_debugger sys/kern/subr_witness.c:2510 [inline] witness_checkorder(ffff80002e46cdc0,9,0) at witness_checkorder+0x10b7 sys/kern/subr_witness.c:1110 mtx_enter(ffff80002e46cdb0) at mtx_enter+0x3e sys/kern/kern_lock.c:265 single_thread_set(ffff8000211f4020,0,1) at single_thread_set+0x35a single_thread_wait sys/kern/kern_sig.c:2172 [inline] single_thread_set(ffff8000211f4020,0,1) at single_thread_set+0x35a sys/kern/kern_sig.c:2155 sigexit(ffff8000211f4020,6) at sigexit+0x90 sys/kern/kern_sig.c:1562 postsig(ffff8000211f4020,6,ffff800029dcd348) at postsig+0x4a9 sys/kern/kern_sig.c:1494 userret(ffff8000211f4020) at userret+0x16e sys/kern/kern_sig.c:1987 syscall(ffff800029dcd480) at syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] syscall(ffff800029dcd480) at syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x8ee02465c70, count: -9 ddb{1}> show registers rdi 0x3 rsi 0xffffffff82b8e4a0 __sancov_gen_cov_switch_values.134 rbp 0xffff800029dcd050 rbx 0x3 rdx 0 rcx 0xffff8000211f4020 rax 0xffff800020d58ff0 r8 0xffff800029dccfc0 r9 0x8080808080808080 r10 0xbd48a52827f9a080 r11 0x74dc0c49bdb60361 r12 0xfffffd8003a0e7a0 r13 0 r14 0xfffffd80039fc6e0 r15 0xfffffd80031cbbc0 rip 0xffffffff810eab1c db_enter+0x1c cs 0x8 rflags 0x246 rsp 0xffff800029dcd040 ss 0x10 db_enter+0x1c: addq $0x8,%rsp ddb{1}> show proc PROC (syz-executor.5) pid=308740 stat=onproc flags process=500000 proc=4002000 pri=32, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff80002127a558,0xffff80002127ad60 process=0xffff80002e46ccb0 user=0xffff800029dc8000, vmspace=0xfffffd806994aaf8 estcpu=36, cpticks=0, pctcpu=0.0 user=0, sys=0, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 28449 221807 13076 0 2 0 syz-executor.3 28449 516294 13076 0 2 0x4000000 syz-executor.3 6175 138692 48348 0 4 0x582000 syz-executor.5 * 6175 308740 48348 0 7 0x4502000 syz-executor.5 6175 174655 48348 0 4 0x4580080 fsleep syz-executor.5 74112 235111 14508 0 3 0x80 nanoslp syz-executor.2 74112 397516 14508 0 3 0x4000080 fsleep syz-executor.2 74112 511803 14508 0 2 0x4000000 syz-executor.2 74112 146170 14508 0 3 0x4000080 fsleep syz-executor.2 6797 376444 74119 0 3 0x3000 suspend syz-executor.4 6797 448903 74119 0 7 0x4081000 syz-executor.4 6797 70656 74119 0 2 0x4081080 syz-executor.4 6797 195968 74119 0 2 0x4081080 syz-executor.4 31328 50333 0 0 3 0x14280 nfsidl nfsio 98978 133470 0 0 3 0x14280 nfsidl nfsio 90385 400523 0 0 3 0x14280 nfsidl nfsio 82164 15649 0 0 3 0x14280 nfsidl nfsio 789 262497 0 0 3 0x14280 nfsidl nfsio 34917 160953 0 0 3 0x14280 nfsidl nfsio 97931 12699 0 0 3 0x14280 nfsidl nfsio 48856 6302 0 0 3 0x14280 nfsidl nfsio 92146 269143 0 0 3 0x14280 nfsidl nfsio 27090 463269 0 0 3 0x14280 nfsidl nfsio 35783 8933 0 0 3 0x14280 nfsidl nfsio 54904 435197 0 0 3 0x14280 nfsidl nfsio 48668 475006 0 0 3 0x14280 nfsidl nfsio 69675 443395 0 0 3 0x14280 nfsidl nfsio 12807 298424 0 0 3 0x14280 nfsidl nfsio 38256 292085 0 0 3 0x14280 nfsidl nfsio 94309 162467 0 0 3 0x14280 nfsidl nfsio 81005 135394 0 0 3 0x14280 nfsidl nfsio 90540 385012 0 0 3 0x14280 nfsidl nfsio 38480 201369 0 0 3 0x14280 nfsidl nfsio 47646 107786 79762 0 3 0x2 biowait syz-executor.6 15067 341141 79762 0 3 0x82 nanoslp syz-executor.7 49313 462093 79762 0 3 0x82 nanoslp syz-executor.1 48348 158676 79762 0 3 0x82 nanoslp syz-executor.5 13076 298320 79762 0 3 0x82 nanoslp syz-executor.3 74119 171806 79762 0 3 0x82 nanoslp syz-executor.4 14508 130853 79762 0 3 0x82 nanoslp syz-executor.2 9694 298536 79762 0 2 0x2 syz-executor.0 79762 361054 3993 0 3 0x2000082 wait syz-fuzzer 79762 29834 3993 0 3 0x6000082 nanoslp syz-fuzzer 79762 518411 3993 0 3 0x6000082 wait syz-fuzzer 79762 409487 3993 0 3 0x6000082 wait syz-fuzzer 79762 174909 3993 0 3 0x6000082 wait syz-fuzzer 79762 486753 3993 0 3 0x6000082 wait syz-fuzzer 79762 407599 3993 0 3 0x6000082 thrsleep syz-fuzzer 79762 202589 3993 0 3 0x6000082 thrsleep syz-fuzzer 79762 149656 3993 0 3 0x6000082 wait syz-fuzzer 79762 304674 3993 0 3 0x6000082 thrsleep syz-fuzzer 79762 362347 3993 0 3 0x6000082 kqread syz-fuzzer 79762 4874 3993 0 3 0x6000082 thrsleep syz-fuzzer 79762 245033 3993 0 3 0x6000082 wait syz-fuzzer 79762 377463 3993 0 3 0x6000082 wait syz-fuzzer 79762 431014 3993 0 3 0x6000082 thrsleep syz-fuzzer 79762 188935 3993 0 3 0x6000082 thrsleep syz-fuzzer 3993 273418 8156 0 3 0x10008a sigsusp ksh 8156 156388 23759 0 3 0x9a kqread sshd 49221 170500 1 0 3 0x100083 ttyin getty 23759 406183 1 0 3 0x88 kqread sshd 10027 164027 83948 74 3 0x1100092 bpf pflogd 83948 302480 1 0 3 0x80 netio pflogd 72952 64775 14401 73 3 0x1100090 kqread syslogd 14401 506480 1 0 3 0x100082 netio syslogd 14245 31538 1 0 3 0x100080 kqread resolvd 95046 315918 63962 77 3 0x100092 kqread dhcpleased 39596 367631 63962 77 3 0x100092 kqread dhcpleased 63962 341202 1 0 3 0x80 kqread dhcpleased 35556 33614 0 0 3 0x14200 bored smr 49219 27429 0 0 2 0x14200 zerothread 20083 30104 0 0 3 0x14200 aiodoned aiodoned 18548 430992 0 0 3 0x14200 syncer update 73605 346201 0 0 3 0x14200 cleaner cleaner 59116 146411 0 0 3 0x14200 reaper reaper 6577 177847 0 0 3 0x14200 pgdaemon pagedaemon 85851 427195 0 0 3 0x14200 bored viomb 57590 203040 0 0 3 0x40014200 acpi0 acpi0 12082 395399 0 0 3 0x40014200 idle1 63109 154230 0 0 3 0x14200 bored softnet3 54331 128286 0 0 3 0x14200 bored softnet2 88734 522121 0 0 3 0x14200 bored softnet1 47286 252551 0 0 3 0x14200 bored softnet0 98111 314849 0 0 3 0x14200 bored systqmp 93999 254716 0 0 3 0x14200 bored systq 88678 212363 0 0 3 0x40014200 bored softclock 59995 74645 0 0 3 0x40014200 idle0 1 265427 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{1}> show all locks CPU 1: exclusive sched_lock &sched_lock r = 0 (0xffffffff82cfb918) #0 witness_lock+0x447 #1 single_thread_set+0x179 sys/kern/kern_sig.c:2113 #2 sigexit+0x90 sys/kern/kern_sig.c:1562 #3 postsig+0x4a9 sys/kern/kern_sig.c:1494 #4 userret+0x16e sys/kern/kern_sig.c:1987 #5 syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] #5 syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 #6 Xsyscall+0x128 Process 6175 (syz-executor.5) thread 0xffff8000211f4020 (308740) exclusive kernel_lock &kernel_lock r = 0 (0xffffffff82c82c68) #0 witness_lock+0x447 #1 postsig+0x49e sys/kern/kern_sig.c:1500 #2 userret+0x16e sys/kern/kern_sig.c:1987 #3 syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] #3 syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 #4 Xsyscall+0x128 exclusive sched_lock &sched_lock r = 0 (0xffffffff82cfb918) #0 witness_lock+0x447 #1 single_thread_set+0x179 sys/kern/kern_sig.c:2113 #2 sigexit+0x90 sys/kern/kern_sig.c:1562 #3 postsig+0x4a9 sys/kern/kern_sig.c:1494 #4 userret+0x16e sys/kern/kern_sig.c:1987 #5 syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] #5 syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 #6 Xsyscall+0x128 Process 47646 (syz-executor.6) thread 0xffff80002124ba98 (107786) exclusive rrwlock inode r = 0 (0xfffffd8069e346f8) #0 witness_lock+0x447 #1 rw_enter+0x3c8 sys/kern/kern_rwlock.c:309 #2 rrw_enter+0x8c sys/kern/kern_rwlock.c:464 #3 VOP_LOCK+0x8b sys/kern/vfs_vops.c:518 #4 ufs_ihashins+0x46 sys/ufs/ufs/ufs_ihash.c:140 #5 ffs_vget+0x141 sys/ufs/ffs/ffs_vfsops.c:1343 #6 ffs_inode_alloc+0x1c2 sys/ufs/ffs/ffs_alloc.c:394 #7 ufs_mkdir+0xf8 sys/ufs/ufs/ufs_vnops.c:1149 #8 VOP_MKDIR+0xc3 sys/kern/vfs_vops.c:388 #9 domkdirat+0x125 sys/kern/vfs_syscalls.c:3073 #10 syscall+0x5e2 mi_syscall sys/sys/syscall_mi.h:110 [inline] #10 syscall+0x5e2 sys/arch/amd64/amd64/trap.c:623 #11 Xsyscall+0x128 exclusive rrwlock inode r = 0 (0xfffffd80661c9928) #0 witness_lock+0x447 #1 rw_enter+0x3c8 sys/kern/kern_rwlock.c:309 #2 rrw_enter+0x8c sys/kern/kern_rwlock.c:464 #3 VOP_LOCK+0x8b sys/kern/vfs_vops.c:518 #4 vn_lock+0x84 sys/kern/vfs_vnops.c:564 #5 vfs_lookup+0xd5 sys/kern/vfs_lookup.c:418 #6 namei+0x55a sys/kern/vfs_lookup.c:250 #7 domkdirat+0x79 sys/kern/vfs_syscalls.c:3058 #8 syscall+0x5e2 mi_syscall sys/sys/syscall_mi.h:110 [inline] #8 syscall+0x5e2 sys/arch/amd64/amd64/trap.c:623 #9 Xsyscall+0x128 ddb{1}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10193 6483K 6498K 78643K 18305 0 pcb 13 8K 8K 78643K 136 0 rtable 234 6K 6K 78643K 348 0 pf 32 9K 10K 78643K 43 0 ifaddr 45 15K 15K 78643K 47 0 ifgroup 55 2K 2K 78643K 55 0 counters 60 35K 35K 78643K 60 0 ioctlops 0 0K 4K 78643K 3643 0 iov 0 0K 0K 78643K 163 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 4 0 vnodes 1285 80K 80K 78643K 2788 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 4 9K 9K 78643K 228 0 VM map 2 1K 1K 78643K 2 0 sem 12 0K 0K 78643K 135 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12548 0 file desc 14 49K 89K 78643K 18354 0 sigio 0 0K 0K 78643K 12 0 proc 67 91K 128K 78643K 526 0 subproc 104 6K 6K 78643K 104 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 in_multi 99 7K 7K 78643K 99 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 61 281K 281K 78643K 61 0 exec 0 0K 1K 78643K 378 0 tdb 3 0K 0K 78643K 3 0 pagedep 1 8K 8K 78643K 1 0 inodedep 1 32K 32K 78643K 1 0 newblk 1 0K 0K 78643K 1 0 VM swap 8 62K 64K 78643K 10 0 UVM amap 329 84K 85K 78643K 155516 0 UVM aobj 131 4K 4K 78643K 131 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 NDP 12 0K 2K 78643K 28 0 temp 73 5916K 5980K 78643K 42082 0 kqueue 12 18K 18K 78643K 22 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 33 0 30 1 0 1 1 0 8 0 rtentry 112 111 0 1 4 0 4 4 0 8 0 unpcb 144 3597 0 3582 7 4 3 4 0 8 2 syncache 304 4 0 4 1 1 0 1 0 8 0 tcpqe 32 151 0 151 1 1 0 1 0 8 0 tcpcb 808 8 0 4 1 0 1 1 0 8 0 arp 120 18 0 0 1 0 1 1 0 8 0 inpcb 368 550 0 543 1 0 1 1 0 8 0 nd6 136 24 0 0 1 0 1 1 0 8 0 kcovpl 48 8 0 0 1 0 1 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 27 0 25 1 0 1 1 0 8 0 pfstkey 128 27 0 25 1 0 1 1 0 8 0 pfstate 376 27 0 25 3 2 1 3 0 8 0 pfrule 1344 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 256 452 0 0 29 0 29 29 0 8 0 art_table 32 453 0 0 4 0 4 4 0 8 0 art_node 16 110 0 10 1 0 1 1 0 8 0 semupl 112 3 0 3 1 1 0 1 0 8 0 semapl 112 133 0 123 1 0 1 1 0 8 0 shmpl 112 128 0 0 4 0 4 4 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 21132 0 19684 91 0 91 91 0 8 0 ffsino 272 21132 0 19684 97 0 97 97 0 8 0 nchpl 144 42120 0 40431 63 0 63 63 0 8 0 uvmvnodes 80 5926 0 0 121 0 121 121 0 8 0 vnodes 216 5926 0 0 330 0 330 330 0 8 0 namei 1024 114525 0 114524 2 1 1 2 0 8 0 percpumem 16 43 0 0 1 0 1 1 0 8 0 kstatmem 264 24 0 0 2 0 2 2 0 8 0 scxspl 216 119430 0 119429 10 9 1 8 1 8 0 plimitpl 152 34 0 18 1 0 1 1 0 8 0 sigapl 424 18687 0 18621 10 2 8 8 0 8 0 futexpl 64 169056 0 169051 1 0 1 1 0 8 0 knotepl 120 114 0 0 4 0 4 4 0 8 0 kqueuepl 216 6730 0 6721 23 17 6 7 0 8 5 pipepl 320 6656 0 6628 19 11 8 8 0 8 5 fdescpl 496 18650 0 18623 5 1 4 5 0 8 0 filepl 152 72014 0 71726 37 22 15 17 0 8 3 lockfpl 104 524 0 522 1 0 1 1 0 8 0 lockfspl 48 256 0 254 1 0 1 1 0 8 0 sessionpl 144 24 0 7 1 0 1 1 0 8 0 pgrppl 48 111 0 94 1 0 1 1 0 8 0 ucredpl 104 6606 0 6594 1 0 1 1 0 8 0 zombiepl 144 18623 0 18621 1 0 1 1 0 8 0 processpl 1072 18687 0 18621 5 0 5 5 0 8 0 procpl 680 38137 0 38047 14 5 9 9 0 8 1 sockpl 488 4180 0 4155 22 10 12 13 0 8 8 mcl64k 65536 25 0 0 3 0 3 3 0 8 0 mcl16k 16384 26 0 0 3 0 3 3 0 8 0 mcl12k 12288 17 0 0 2 0 2 2 0 8 0 mcl9k 9216 17 0 0 2 0 2 2 0 8 0 mcl8k 8192 19 0 0 3 0 3 3 0 8 0 mcl4k 4096 28 0 0 3 0 3 3 0 8 0 mcl2k2 2112 12 0 0 1 0 1 1 0 8 0 mcl2k 2048 318 0 0 37 4 33 37 0 8 0 mtagpl 96 3 0 0 1 0 1 1 0 8 0 mbufpl 256 545 0 0 19 0 19 19 0 8 0 bufpl 288 22449 0 16120 453 0 453 453 0 8 0 anonpl 24 1397920 0 1389526 68 14 54 59 0 186 0 amapchunkpl 152 487855 0 487090 52 18 34 34 0 158 2 amappl16 200 20564 0 20388 10 0 10 10 0 8 0 amappl15 192 44 0 42 1 0 1 1 0 8 0 amappl14 184 156 0 142 2 1 1 2 0 8 0 amappl13 176 22 0 21 1 0 1 1 0 8 0 amappl12 168 19327 0 19298 4 1 3 3 0 8 0 amappl11 160 73 0 58 1 0 1 1 0 8 0 amappl10 152 25 0 16 1 0 1 1 0 8 0 amappl9 144 2458 0 2458 1 0 1 1 0 8 1 amappl8 136 437 0 339 4 0 4 4 0 8 0 amappl7 128 276 0 265 2 0 2 2 0 8 0 amappl6 120 267 0 248 2 1 1 2 0 8 0 amappl5 112 548 0 536 1 0 1 1 0 8 0 amappl4 104 1632 0 1591 3 1 2 3 0 8 0 amappl3 96 98905 0 98823 4 1 3 3 0 8 0 amappl2 88 21004 0 20937 3 1 2 3 0 8 0 amappl1 80 69928 0 69373 23 11 12 23 0 8 0 amappl 88 154621 0 154417 6 0 6 6 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 72 130 0 0 3 0 3 3 0 8 0 uaddrrnd 24 18650 0 18623 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 18650 0 18623 1 0 1 1 0 8 0 vmmpekpl 168 118092 0 118024 4 0 4 4 0 8 0 vmmpepl 168 995876 0 993826 135 37 98 119 0 357 2 vmsppl 464 18649 0 18623 5 1 4 5 0 8 0 rwobjpl 56 208998 0 201646 112 8 104 105 0 8 0 pdppl 4096 37308 0 37246 292 222 70 82 0 8 8 pvpl 32 4430004 0 4415849 373 248 125 367 0 265 0 pmappl 248 18649 0 18623 3 1 2 3 0 8 0 extentpl 40 56 0 38 1 0 1 1 0 8 0 phpool 112 1055 0 234 24 0 24 24 0 8 0 ddb{1}> machine ddbcpu 0 Stopped at x86_ipi_db+0x1e: addq $0x8,%rsp ddb{0}> trace x86_ipi_db(ffffffff82be4ff0) at x86_ipi_db+0x1e sys/arch/amd64/amd64/db_interface.c:393 x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 __mp_lock(ffffffff82c82a60) at __mp_lock+0x122 __mp_lock_spin sys/kern/kern_lock.c:116 [inline] __mp_lock(ffffffff82c82a60) at __mp_lock+0x122 sys/kern/kern_lock.c:147 intr_handler(ffff80002e493b30,ffff80000006bc00) at intr_handler+0x62 sys/arch/amd64/amd64/intr.c:532 Xintr_ioapic_edge23_untramp() at Xintr_ioapic_edge23_untramp+0x18f __mp_lock(ffffffff82c82a60) at __mp_lock+0x129 __mp_lock_spin sys/kern/kern_lock.c:116 [inline] __mp_lock(ffffffff82c82a60) at __mp_lock+0x129 sys/kern/kern_lock.c:147 single_thread_check_locked(ffff80002124ad50,0) at single_thread_check_locked+0x23a sys/kern/kern_sig.c:2033 userret(ffff80002124ad50) at userret+0x72 single_thread_check sys/kern/kern_sig.c:2060 [inline] userret(ffff80002124ad50) at userret+0x72 sys/kern/kern_sig.c:1970 syscall(ffff80002e493de0) at syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] syscall(ffff80002e493de0) at syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x45c355194b0, count: -11 ddb{0}> machine ddbcpu 1 Stopped at db_enter+0x1c: addq $0x8,%rsp ddb{1}> trace db_enter() at db_enter+0x1c sys/arch/amd64/amd64/db_interface.c:437 witness_checkorder(ffff80002e46cdc0,9,0) at witness_checkorder+0x10b7 witness_debugger sys/kern/subr_witness.c:2510 [inline] witness_checkorder(ffff80002e46cdc0,9,0) at witness_checkorder+0x10b7 sys/kern/subr_witness.c:1110 mtx_enter(ffff80002e46cdb0) at mtx_enter+0x3e sys/kern/kern_lock.c:265 single_thread_set(ffff8000211f4020,0,1) at single_thread_set+0x35a single_thread_wait sys/kern/kern_sig.c:2172 [inline] single_thread_set(ffff8000211f4020,0,1) at single_thread_set+0x35a sys/kern/kern_sig.c:2155 sigexit(ffff8000211f4020,6) at sigexit+0x90 sys/kern/kern_sig.c:1562 postsig(ffff8000211f4020,6,ffff800029dcd348) at postsig+0x4a9 sys/kern/kern_sig.c:1494 userret(ffff8000211f4020) at userret+0x16e sys/kern/kern_sig.c:1987 syscall(ffff800029dcd480) at syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] syscall(ffff800029dcd480) at syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x8ee02465c70, count: -9