Date: Sun, 15 Jun 2003 09:57:43 -0700 From: David Schultz <das@FreeBSD.ORG> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: freebsd-bugs@FreeBSD.ORG Subject: Re: kern/53350: fill up a malloc md-disk on 5.1-R causes panic Message-ID: <20030615165743.GA1835@HAL9000.homeunix.com> In-Reply-To: <200306151630.h5FGUFGV084676@freefall.freebsd.org> References: <200306151630.h5FGUFGV084676@freefall.freebsd.org>
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On Sun, Jun 15, 2003, Poul-Henning Kamp wrote:
> The following reply was made to PR kern/53350; it has been noted by GNATS.
>
> From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
> To: Jay Kuri <jay@oneway.com>
> Cc: FreeBSD-gnats-submit@freebsd.org
> Subject: Re: kern/53350: fill up a malloc md-disk on 5.1-R causes panic
> Date: Sun, 15 Jun 2003 18:24:17 +0200
>
> >>Description:
> > If you have a 5.1-R system with, say, 256M of ram
> >and you mdconfig one or several malloc md-devices totalling around 100M,
> >if you attempt to use them to capacity, the machine will panic. The
> >message given is:
> >
> > panic: kmem_malloc(4096): kmem_map too small: 108347392 total allocated
Dedicating more than a third of your physical memory to
malloc-backed storage is kind of insane anyway, but you can do it
if you specify a VM_KMEM_SIZE_SCALE of 1 or 2 in your kernel config.
> It's really very simple: You ran out of kernel mapped memory ("KVM").
>
> Remedy: Don't Do That.
>
> See also: malloc(9), md(4)
>
> This PR can be closed.
The kmem_map limitations are a FAQ and should probably be
documented as such.
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