kern/44402: page fault in supervisor mode in netbsd:filt_piperead

[kristerw%netbsd.org@localhost]

>Number:         44402
>Category:       kern
>Synopsis:       page fault in supervisor mode in netbsd:filt_piperead
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Jan 16 18:30:01 +0000 2011
>Originator:     Krister Walfridsson
>Release:        current as of Jan 15
>Organization:
>Environment:
NetBSD scratch 5.99.43 NetBSD 5.99.43 (GENERIC) #0: Sat Jan 15 02:02:22 CET 
2011  
cato%pc5.kwa@localhost:/usr/local/tmp/nbsd110114/obj.i386/sys/arch/i386/compile/GENERIC
 i386
>Description:
Running the current ghc testsuite crash my kernel with

uvm_fault(0xce3c6774, 0, 1) -> 0xe
fatal page fault in supervisor mode
trap type 6 code 0 eip c0638803 cs 8 eflags 10296 cr2 0 ilevel 0
kernel: supervisor trap page fault, code=0
Stopped in pid 924.2 (ghc-stage2) at   netbsd:filt_piperead+0xf3: movl 0 
(%ebx),%eax

This is on a rather new PC, so it does not have any serial port, and the USB 
keyboard does not work at the DDB prompt, so it is a bit problematic to get 
more information...
>How-To-Repeat:
I can reproduce the error within a minute by running the following script using 
a -current ghc:

#!/bin/sh
while :
do
        echo -n .
        rm -f cgrun037.comp.stderr
        /usr/local/tmp/ghc20110114/ghc/inplace/bin/ghc-stage2 -fforce-recomp 
-dcore-lint -dcmm-lint -dno-debug-output -no-user-package-conf -rtsopts  -o 
cgrun037 cgrun037.hs >cgrun037.comp.stderr 2>&1
done

>Fix: