uvm_fault in filt_sordetach

[Mark Davies <mark%mcs.vuw.ac.nz@localhost>]

Hi,
   I have a 4.99.52 i386 box that 3 times now in the last week has 
died with a uvm_fault in filt_sordetach(). It drops into the debugger 
but unfortunately the usb keyboard doesn't respond so I can't poke 
around, but I did get a backtrace from the last one:

Stopped in pid 490.1 (httpd) at netbsd:filt_sordetach+0x22
        filt_sordetach()
        kqueue_close()
        closef()
        syscall()

The process has been httpd in all three cases.

Suggestions?

cheers
mark