kldunload Fatal trap 12: page fault

[esmith <esmith@xxxxxxxxxxxx>]

This is a consistent reproducible problem. I think a similar problem was 
reported on a FreeBSD list during early 2003.

The first time kldload and "kldunload snd_ich" are called they work 
correctly. When ever kldload snd_ich is called again there after, it 
reports this (though sound still works):

pcm0: <Intel ICH2 (82801BA)> port 0xe000-0xe03f,0xdc00-xdcff irq 12 at 
device 31.5 on pci0
icu_unset: invalid handler 12 0x017cf0/0xc02ddbdc
pcm0: <SigmaTel ... codec>

If the improper driver is kldloaded ( such as snd_sb16 ) , it does load, 
however, when kldunload is called it causes a page fault

Fatal trap 12: page fault while in kernel mode
fault virtual address = ...
fault code = supervisor read, page not present
. ..
processor eflags = resume, IOPL = 0
current process = 1131 (kldunload)
. ..
kernel: type 12 trap, code=0