panic: pmap_remove_all: illegal for unmanaged/fake page 0x9d2000

Sun E250, running world/kernel from September 18th.
While running a make buildworld, I get :

panic: pmap_remove_all: illegal for unmanaged/fake page 0x9d2000
cpuid = 0;
Debugger("panic")
Stopped at      Debugger+0x1c:  ta              %xcc, 1
db> trace
panic() at panic+0x174
pmap_remove_all() at pmap_remove_all+0x38
vm_object_page_remove() at vm_object_page_remove+0x164
vm_map_delete() at vm_map_delete+0x1d8
vm_map_remove() at vm_map_remove+0x44
kmem_free() at kmem_free+0x20
page_free() at page_free+0x2c
zone_drain_common() at zone_drain_common+0x340
zone_drain() at zone_drain+0x8
zone_foreach() at zone_foreach+0x30
uma_reclaim() at uma_reclaim+0x10
vm_pageout_scan() at vm_pageout_scan+0x13c
vm_pageout() at vm_pageout+0x380
fork_exit() at fork_exit+0x9c
fork_trampoline() at fork_trampoline+0x8
db>

It seems I can reliably reproduce this just
by running make buildworld.  I usually clear the /usr/obj/src
directory before staring a new make buildworld.

The first time it got to this before panicing:


c++ -fPIC -DPIC -O -pipe -DIN_GLIBCPP_V3 -DHAVE_CONFIG_H -I/usr/src/gnu/lib/libstdc++ -I/usr/src/gnu/lib/libstdc++/../../../contrib/
libstdc++/libsupc++ -I/usr/src/gnu/lib/libstdc++/../../../contrib/gcc -fno-implicit-templates -ffunction-sections -fdata-sections -W
no-deprecated -c /usr/src/contrib/libstdc++/src/locale.cc -o locale.So
c++ -fPIC -DPIC -O -pipe -DIN_GLIBCPP_V3 -DHAVE_CONFIG_H -I/usr/src/gnu/lib/libstdc++ -I/usr/src/gnu/lib/libstdc++/../../../contrib/
libstdc++/libsupc++ -I/usr/src/gnu/lib/libstdc++/../../../contrib/gcc -fno-implicit-templates -ffunction-sections -fdata-sections -W
no-deprecated -c /usr/src/contrib/libstdc++/src/locale-inst.cc -o locale-inst.So
<panic on console here>


The other 4 times were all when compiling this:


cc -pg -O -pipe  -I/usr/src/lib/libc/include -I/usr/src/lib/libc/../../include -I/usr/src/lib/libc/sparc64 -I/usr/src/lib/libc/sparc64/sys -D__DBINTERFACE_PRIVATE -I/usr/src/lib/libc/../../contrib/gdtoa -DINET6 -I/usr/obj/usr/src/lib/libc -DPOSIX_MISTAKE -I/usr/src/lib/libc/locale -I/usr/src/lib/libc/sparc64/fpu -DBROKEN_DES -DPORTMAP -DDES_BUILTIN -I/usr/src/lib/libc/rpc -DYP -DHESIOD  -c /usr/src/lib/libc/string/wmemmove.c -o wmemmove.po
cc -pg -O -pipe  -I/usr/src/lib/libc/include -I/usr/src/lib/libc/../../include -I/usr/src/lib/libc/sparc64 -I/usr/src/lib/libc/sparc64/sys -D__DBINTERFACE_PRIVATE -I/usr/src/lib/libc/../../contrib/gdtoa -DINET6 -I/usr/obj/usr/src/lib/libc -DPOSIX_MISTAKE -I/usr/src/lib/libc/locale -I/usr/src/lib/libc/sparc64/fpu -DBROKEN_DES -DPORTMAP -DDES_BUILTIN -I/usr/src/lib/libc/rpc -DYP -DHESIOD  -c /usr/src/lib/libc/string/wmemset.c -o wmemset.po
<panic on console here>

All of the trace's look the same.