Re: 2.6.22-rc1-mm1

From: Andy Whitcroft
Date: Thu Jun 07 2007 - 05:50:38 EST


H. Peter Anvin wrote:
> Andy Whitcroft wrote:
>>> It definitely sounds like a memory clobber of some sort.
>>>
>>> Usual suspects, in addition to the input/output buffers you already
>>> looked at, would be the heap and the stack. Finding where the stack
>>> pointer lives would be my first, instinctive guess.
>> The stack seems to be where it should be and seems to stay pretty much
>> in the same place as it should. Adding checks for the heap also seem to
>> stay within bounds. I've tried making the stack and the heap 64k to no
>> effect.
>>
>> Moving the kernel to other places in memory seems to kill the decode
>> completely during gunzip() which may be a hint I am not sure.
>>
>> This thing is trying to ruin my mind.
>>
>
> Yours and mine both. Seems like *something* is clobbering memory, but
> what and why is a mystery. The fact that putting the kernel in a higher
> point in memory is a good indication that this clobber is at a
> relatively high address.
>
> How much RAM does this machine have?

This is as 12GB machine. 3 numa nodes.

I checked out the location of the IDT and GDT and both seem sane, in the
9xxxx range below the kernel destination.

I also note that on another machine of this type, one Node only in that
case some of the "did work" cases do not work. Also when I applied some
of my patches on the top "working" cases stopped working. So whatever
it is is definatly related to the shape of the kernel to be loaded.
Very confusing.

-apw
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