On 22/06/11 10:44, Mel Gorman wrote:
> I haven't started looking at this properly yet (stuck with other
> bugs unfortunately) but I glanced at the sysrq message and on a 2G
> 64-bit machine, you have a tiny Normal zone! This is very unexpected.
> Can you boot with mminit_loglevel=4 loglevel=9 and post your full
> dmesg please? I want to see what the memory layout of this thing
> looks like to see in the future if there is a correlation between
> this type of bug and a tiny highest zone.

Note this machine has 3G RAM
dmesg attached

> 
> Broadly speaking though from seeing that, it reminds me of a
> similar bug where small zones could keep kswapd alive for high-order
> allocations reclaiming slab constantly. I suspect on your machine
> that the Normal zone cannot be balanced for order-0 allocations and
> is keeping kswapd awake.
> 
> Can you try booting with mem=1792M and if the Normal zone disappears,
> try reproducing the bug?
> 

I tried mem=1792M but grub gave an ENOSPC error
Maybe I need to supply a memmap= too?

cheers,
Padraig.