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From: Dmitry Sivachenko <trtrmitya@gmail.com>
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Subject: 9-STABLE panic on intensive fork
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Date: Wed, 28 Aug 2013 18:20:29 +0400
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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. =20

Thanks!=