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Date:      Thu, 25 May 2006 19:56:07 -0400
From:      "Jonathan Noack" <noackjr@alumni.rice.edu>
To:        "Kris Kennaway" <kris@obsecurity.org>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: kmem leak in tmpmfs?
Message-ID:  <44764417.4030004@alumni.rice.edu>
In-Reply-To: <20060525205414.GC30137@xor.obsecurity.org>
References:  <wpy7wq6qlh.fsf@heho.labo> <20060525205414.GC30137@xor.obsecurity.org>

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Kris Kennaway wrote:
> On Thu, May 25, 2006 at 06:01:30PM +0200, Arno J. Klaassen wrote:
>> I get a very easy to reproduce panic on 6.1-STABLE :
>>
>> /etc/periodic/weekly/310.locate panics with
>>
>>   panic: kmem_malloc(4096): kmem_map too small: 335544320 total allocated
> 
> It looks like you are using a malloc-backed md and you do not have
> enough RAM to handle the size.  Perhaps tmpmfs does not use swap
> backing, as it is supposed to?

If you look in /etc/defaults/rc.conf you'll note that malloc-backed is 
the default:
tmpmfs_flags="-S -M"    # Extra mdmfs options for the mfs /tmp

I don't really understand why malloc-backed is the default as the 
performance difference between malloc- and swap-backed md's was resolved 
long ago:
http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/dev/md/md.c#rev1.117

Ah, it looks like this was just for compatibility:
http://www.freebsd.org/cgi/cvsweb.cgi/src/etc/defaults/rc.conf#rev1.259

I am currently running with the following in /etc/rc.conf and haven't 
experienced any problems:
tmpmfs_flags="-S -o async"

-Jonathan



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