kern/45361: Consistent kernel panic when building qemu in amd64

[jmmv%netbsd.org@localhost]

>Number:         45361
>Category:       kern
>Synopsis:       Consistent kernel panic when building qemu in amd64
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Sep 12 19:25:00 +0000 2011
>Originator:     Julio Merino
>Release:        NetBSD 5.99.55
>Organization:
Julio Merino
>Environment:
        
        
System: NetBSD netbsd.virtual.network 5.99.55 NetBSD 5.99.55 (GENERIC) #0: Mon 
Sep 12 11:20:49 EDT 2011  
builder@netbsd.virtual.network:/home/builder/obj/usr/src/sys/arch/amd64/compile/GENERIC
 amd64
Architecture: x86_64
Machine: amd64
>Description:
        Running NetbSD/amd64 current (as of today), with DIAGNOSTIC enabled,
        consistently panics when building the qemu package.

        I can see this in messages:

        Sep 12 15:14:26 netbsd syslogd[211]: restart
        Sep 12 15:14:26 netbsd /netbsd: pmap_kenter_pa: mapping already present
        Sep 12 15:14:26 netbsd syslogd[211]: last message repeated 2 times
        Sep 12 15:14:26 netbsd /netbsd: uvm_fault(0xffff800048bd02e8, 
0x7f7ff0d1b000, 1) -> e
        Sep 12 15:14:26 netbsd /netbsd: fatal page fault in supervisor mode
        Sep 12 15:14:26 netbsd /netbsd: trap type 6 code 0 rip ffffffff806fae06 
cs 8 rflags 10297 cr2  7f7ff0d1bf20 cpl 6 rsp ffff800048bbd990
        Sep 12 15:14:26 netbsd /netbsd: panic: trap
        Sep 12 15:14:26 netbsd /netbsd: cpu3: Begin traceback...
        Sep 12 15:14:26 netbsd /netbsd: startlwp() at netbsd:startlwp
        Sep 12 15:14:26 netbsd /netbsd: alltraps() at netbsd:alltrapsu+v0mx_af2a
        Sep 12 15:14:26 netbsd /netbsd: ult(0xffff8000490aba28, 0x7f7ff0d1e000, 
1) -> e
        Sep 12 15:14:26 netbsd /netbsd: fatal page fault in supervisor mode
        Sep 12 15:14:26 netbsd /netbsd: trap type 6 code 0 rip ffffffff806fac39 
cs 8 rflkagesv e1n0t219(7)  cart2   7f7ff0d1eb10 cpl 8 rsp 
ffff800n0e4tcb4s2df:7kbe0v
        Sep 12 15:14:26 netbsd /netbsd: ent1+0x2b6
        Sep 12 15:14:26 netbsd /netbsd: sys___kevent50() at 
netbsd:sys___kevent50+0x33
        Sep 12 15:14:26 netbsd /netbsd: syscall() at netbsd:syscall+0xac
        Sep 12 15:14:26 netbsd /netbsd: cpu3: End traceback...

        I have a crash dump available that might provide more information if 
needed.
>How-To-Repeat:
        Update to current amd64 and then build the qemu package.  Hopefully see
        the system panic or get stuck.
>Fix:
        

>Unformatted: