'panic: bad pte' error on 6.2-RELEASE (amd64)

[Peter Losher]

We recently updated one of our dual Opteron systems (w/ 4GB RAM) from
5.5 to 6.2 (amd64 wipe and reinstalled) and about once a week, it panics
with the below message:

-=-
TPTE at 0xffff8000040028a0  IS ZERO @ VA 800514000
panic: bad pte
cpuid = 2
KDB: stack backtrace:
panic() at 0xffffffff803fdd03 = panic+0x253
pmap_remove_pages() at 0xffffffff806072a3 = pmap_remove_pages+0x283
exec_new_vmspace() at 0xffffffff803e18e6 = exec_new_vmspace+0x216
exec_elf64_imgact() at 0xffffffff803cbb73 = exec_elf64_imgact+0x273
kern_execve() at 0xffffffff803e2107 = kern_execve+0x457
execve() at 0xffffffff803e2bed = execve+0x5d
syscall() at 0xffffffff8060d141 = syscall+0x4d1
Xfast_syscall() at 0xffffffff805f8128 = Xfast_syscall+0xa8
--- syscall (59, FreeBSD ELF64, execve), rip = 0x80069838c, rsp =
0x7fffffffe7c8, rbp = 0x7fffffffecd0 ---
Uptime: 4d16h55m46s
-=-

I do have a dump, and can make that available if need be.  Has anyone
encountered this recently and can shed any light on what might be
causing this?

Best Wishes - Peter

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