Kernel memory corruption(?) with age(4)

[Yamagi Burmeister]

On Thu, 31 Mar 2011, YongHyeon PYUN wrote:

>> All boxes are quadcore machines with 8GB RAM, running FreeBSD/amd64.
>> After limiting the memory via hw.physmem to 3GB the problems are gone.
>> The box is running crashfree for more than 6 hours and has served over
>> 300GB of data via age(4).
>>
>
> Thanks for testing. Remove the hw.physmem configuration and try
> attached patch and let me know how it goes.

Thanks for your help, but the patch doesn't work. Another random panic -
this time "page fault in kernel mode" - with nothing age(4) or network
stack related stuff in the backtrace...

Maybe it'll help to know about a bug fix in the linux atl1 driver, now
replaced by atlx. In git commit 5f08e46b621a769e52a9545a23ab1d5fb2aec1d4
64 bit DMA was disabled:

   64-bit DMA causes data corruption with atl1.  We don't know why, and
   Atheros is working on it. For now, just use 32-bit DMA. This is a big
   hack that is probably wrong, but it stops the bleeding.

There was no later follow up on it. I think that this can't be problem
on FreeBSD but maybe I'm reading the driver code wrong. The kernel.org
gitweb URL is:

http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.23.y.git;a=commitdiff;h=5f08e46b621a769e52a9545a23ab1d5fb2aec1d4

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