9-STABLE panic on intensive fork

[Dmitry Sivachenko]

Hello!

I am using very recent FreeBSD-9-STABLE snapshot:
9.2-PRERELEASE FreeBSD 9.2-PRERELEASE #0 r254986: Wed Aug 28 17:18:57 MSK 2013

I run uwsgi program (ports/www/uwsgi) on that machine.

When uwsgi starts, it forks pre-configured number of worker processes.
If I raise workers parameter high enough (128), I get kernel panic (100% reproducible):

Fatal trap 12: page fault while in kernel mode

If I compile kernel with KDB enabled, I get the following stack:

pmap_demote_pde_locked()
pmap_copy()
vmspace_fork()
fork1()
sys_fork()

I have only remote console for that machine, so I made 2 screenshots:

1) http://people.freebsd.org/~demon/screen1.jpg
Panic screen when kernel has no KDB support compiled in

2) http://people.freebsd.org/~demon/screen2.jpg
Panic screen (2nd part) with the above stack shown.

I can provide any additional information if needed.  

Thanks!