In <200010191504.e9JF4Wg01672@mirage.ceres.dti.ne.jp>
I wrote:

> pmap->pm_refcount is _not_ initialized to 1 in pmap_pinit().
> So pmap_dereference() which is called from pmap_destroy()
> would return a negative value, then most pmap structures would
> never be free()'d. I think that's the problem.
> 
> I'll try another make build with newer kernel.

After 20 hours make build was started, dump_kmemstats() reports:

> 34 VM pmap               448

The kernel without the fixes wastes more than 1M bytes.
I think we've got it. 

I'll commit and request to pullup the fixes after more testing
a kernel with pmap_lock().
---
Izumi Tsutsui
tsutsui@ceres.dti.ne.jp