Ok, I think I've found some, but not all of the missing memory.

I had to remove PG_swapbacked and PG_private2 as 2.6.26/2.6.27 didn't
have those bits.

After that, a comparison shows that this row is in 2.6.27, but not
2.6.26:

0x00020	     20576       80  _____l____________  lru

Unfortunately there are about 170 MB of missing memory, not 80. So we
probably need to dig deeper. But does the above say anything to you?

Rgds
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