kern/45991: posix_spawn causes panic

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

>Number:         45991
>Category:       kern
>Synopsis:       posix_spawn causes panic
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Feb 12 04:35:00 +0000 2012
>Originator:     Izumi Tsutsui
>Release:        NetBSD 5.99.65 updated around 201202120100Z
>Organization:
>Environment:
System: NetBSD 5.99.65 GENERIC built by build.sh release
Architecture: i386
Machine: i386
On old PentiumM uniprocessor PC
>Description:
configure check against posix_spawn in pkgsrc/devel/m4 causes kernel panic:
---
 :
checking for promoted mode_t type... mode_t
checking for posix_spawn works... fatal page fault in supervisor mode
trap type 6 code 0 eip c06abe6f cs 8 eflags 10246 cr2 0 ilevel 0
kernel: supervisor trap page fault, code=0
Stopped in pid 11336.1 (conftest) at    netbsd:pmap_deactivate+0x74:    movl    0
(%eax),%ebx
db{0}> tr
pmap_deactivate(c3411aa0,0,dba16c8c,,c3417054,c3411aa0,906,c3417054,93a97b98,0,c3417054)
 at netbsd:pmap_deactivate+0x74
uvm_proc_exit(c340188c,0,dba16c8c,c3411800,c0c5e800,c1889240,dba16c6c,c057949f,dba16c8c,2)
 at netbsd:uvm_proc_exit+0x3f
exit1(c3411aa0,906,0,0,dba16d0c,c0c5e800,c3411aa0,c340188c,0,c1aec658) at 
netbsd:exit1+0x187
spawn_return(c1af6c40,b3,ab,bfbf001f,bb91001f,bfbfe190,0,bfbfe1c4,80490ec,bb906040)
 at netbsd:spawn_return+0x559
db{0}>
---

(typed from screen, sorry if any typo)

>How-To-Repeat:
install 5.99.65 via sysinst
get and extract pkgsrc-2011Q4.tar.xz tree
cd pkgsrc/devel/m4 ; make update

>Fix:
Prepare proper tests?