kmem leak in tmpmfs?

[Jonathan Noack]

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