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Date:      Mon, 7 May 2001 07:56:12 -0700 (PDT)
From:      Dennis Glatting <dennis.glatting@software-munitions.com>
To:        Kris Kennaway <kris@obsecurity.org>
Cc:        <freebsd-stable@frebsd.org>, <freebsd-current@freebsd.org>
Subject:   Re: pgm to kill 4.3 via vm
Message-ID:  <20010507074503.Y24943-100000@btw.plaintalk.bellevue.wa.us>
In-Reply-To: <20010506044724.A24309@xor.obsecurity.org>

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On Sun, 6 May 2001, Kris Kennaway wrote:

> On Sat, May 05, 2001 at 02:37:07PM -0700, Dennis Glatting wrote:
> >
> > I wrote a trivial program to fill vm and found I can reliably freeze my
> > system. It may not work on the first attempt, but certainly within three.
> > My command line is:
> >
> > 	a.out&;a.out&;a.out&;a.out&;a.out&
> >
> > The goal of my program is simply to see how the system behaves under
> > memory exhaustion which, as it turns out on two similar systems, the
> > systems freeze. Specifically, I can switch between consoles but the login
> > prompts do not respond and the system does not respond on the network.
> >
> > I am running 4.3 on a dual processor system.
> >
> > Below are some things. First, the program. Second, dmesg. Finally, my
> > /etc/rc.config.
>
> What resource limits have you set?
>


I haven't set any, so it's the default.

I am intentionally testing at the limits to see what happens, usually
interesting things. :) In this case, the application is well behaved (in
the error proccesing sense):  it'll exit, thus releasing its memory
resources, when the kernel reports a memory allocation failure.

(Within the last six months I commited less than 10 systems to production
roles. Consequently, I'm interested in how FreeBSD behaves should any of
the applications behave badly.)

I've run this code on four systems, all 4.3. Two of the systems are
similar SMP boxes; one a P3 233; and the last a P3 500 lap top. The code
eventually crashed all systems (less than three runs) and sometimes
printed an error message about a swap allocation failure.

In the worst case I expect an error message, like "gone fishing, bye.",
but that isn't the case; so my suspecion is a bug that those who know the
kernel better than I might pursue.

TIA








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