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Date: Mon, 5 Mar 2007 16:23:50 +0300
From: Yar Tikhiy <yar@comp.chem.msu.su>
To: Kris Kennaway <kris@obsecurity.org>
Message-ID: <20070305132350.GB57253@comp.chem.msu.su>
References: <20070227205351.GA72597@ravenloft.kiev.ua>
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Cc: stable@freebsd.org, Alex Kozlov <spam@rm-rf.kiev.ua>,
	Mikhail Teterin <mi+kde@aldan.algebra.com>
Subject: Re: panic: kmem_malloc(16384): kmem_map too small: md-mounted /tmp
	filled up
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On Sun, Mar 04, 2007 at 10:59:46PM -0500, Kris Kennaway wrote:
> On Sun, Mar 04, 2007 at 10:59:46AM +0300, Yar Tikhiy wrote:
> > On Tue, Feb 27, 2007 at 04:03:30PM -0500, Mikhail Teterin wrote:
> > > On Tuesday 27 February 2007 15:53, Alex Kozlov wrote:
> > > = > Yes, I switched to swap-backed md already. But the malloc-based variety is 
> > > = > currently the _default_ (see /etc/defaults/rc.conf)...
> > > = Bad default.
> > > 
> > > Filing a PR.
> > 
> > Keep in mind that changing the default can break existing setups.
> > Such setups are likely to be broken anyway, but...  E.g., if we
> > drop the -M flag, it will break systems with tons of RAM but little
> > swap using tmpmfs.
> 
> How will it break them?  swap backing only touches swap if there is
> memory pressure, i.e. precisely the situation in which malloc backing
> will panic.

I forgot that in BSD swap wouldn't be allocated in advance to its
consumers.  Then removing the -M flag and making swap backing the
default is a very sound choice.  Thank you for correcting me.

-- 
Yar