r365488 page faults on AMD Ryzen 9 3950X

Since r365488 (and above until recent) my box breaks with the following
error when starting:

Fatal trap 12: page fault while in kernel mode
cpuid = 31; apic id = 1f
fault virtual address   = 0x0
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff808f452b
stack pointer           = 0x28:0xffffffff81711800
frame pointer           = 0x28:0xffffffff81711800
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 0 (swapper)
trap number             = 12
panic: page fault
cpuid = 31
time = 1



Some infos about the system, the page fault occurs:

CPU: AMD Ryzen 9 3950X 16-Core Processor             (3493.50-MHz
K8-class CPU)
  Origin="AuthenticAMD"  Id=0x870f10  Family=0x17  Model=0x71  Stepping=0
Features=0x178bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2,HTT>
Features2=0x7ed8320b<SSE3,PCLMULQDQ,MON,SSSE3,FMA,CX16,SSE4.1,SSE4.2,MOVBE,POPCNT,AESNI,XSAVE,OSXSAVE,AVX,F16C,RDRAND>
  AMD Features=0x2e500800<SYSCALL,NX,MMX+,FFXSR,Page1GB,RDTSCP,LM>
  AMD
Features2=0x75c237ff<LAHF,CMP,SVM,ExtAPIC,CR8,ABM,SSE4A,MAS,Prefetch,OSVW,IBS,SKINIT,WDT,TCE,Topology,PCXC,PNXC,DBE,PL2I,MWAITX,ADMSKX>
  Structured Extended
Features=0x219c91a9<FSGSBASE,BMI1,AVX2,SMEP,BMI2,PQM,PQE,RDSEED,ADX,SMAP,CLFLUSHOPT,CLWB,SHA>
  Structured Extended Features2=0x400004<UMIP,RDPID>
  XSAVE Features=0xf<XSAVEOPT,XSAVEC,XINUSE,XSAVES>
  AMD Extended Feature Extensions ID
EBX=0x108b657<CLZERO,IRPerf,XSaveErPtr,RDPRU,WBNOINVD,IBPB,STIBP,SSBD>
  SVM: (disabled in BIOS) NP,NRIP,VClean,AFlush,DAssist,NAsids=32768
  TSC: P-state invariant, performance statistics
real memory  = 68717379584 (65534 MB)
avail memory = 66756149248 (63663 MB)
Event timer "LAPIC" quality 600


#cat /etc/sysctl.conf
security.bsd.map_at_zero=1
kern.module_path=/boot/kernel;/boot/modules;/usr/local/modules
kern.evdev.rcpt_mask=6
kern.maxfiles=49312
kern.ipc.shm_allow_removed=1
kern.ipc.maxsockbuf=16777216
vfs.usermount=1
net.inet.tcp.rfc1323=1
net.inet.tcp.sack.enable=1
net.inet.tcp.sendbuf_auto=1
net.inet.tcp.recvbuf_auto=1
net.inet.tcp.sendbuf_max=16777216
net.inet.tcp.recvbuf_max=16777216
net.inet6.ip6.use_tempaddr=1
net.inet6.ip6.prefer_tempaddr=1
net.local.stream.recvspace=65536
net.local.stream.sendspace=65536


Please let me know, if I should provide more info or test something.
Thanks in advance,
Rainer