panic: vm_fault: fault on nofault entry, addr: fffffe0007e8e000

I upgraded the alpha package machines tonight, and one of them fell
over shortly after taking load, with the following:

panic: vm_fault: fault on nofault entry, addr: fffffe0007e8e000
Stack backtrace:
db_print_backtrace() at db_print_backtrace+0x18
backtrace() at backtrace+0x2c
panic() at panic+0x148
vm_fault() at vm_fault+0x1360
trap() at trap+0x5c8
XentMM() at XentMM+0x2c
--- memory management fault (from ipl 0) ---
bcopy_samealign_lp() at bcopy_samealign_lp
cpu_fork() at cpu_fork+0x12c
vm_forkproc() at vm_forkproc+0x204
fork1() at fork1+0xfec
vfork() at vfork+0x30
syscall() at syscall+0x33c
XentSys() at XentSys+0x64
--- syscall (66) ---
--- user mode ---


Kris