hippo, here is what I am seeing - I am doing a simple test where I copy a large file (35M Linux BZ2 kernel) from one MMC partition to another.
In 2.6.12, I can telnet in about 3 different sessions before it crashes.
In 2.6.14, I can maybe get only 2 sessions.
In 2.6.15, it will bomb as soon as I do anything else. If I have a UART session open, and a telnet session open executing the 'cp' command, and do something like cat /proc/meminfo while the copy is taking place, it gets page allocation failures.
So I'm not sure if this is a bug, not enough RAM, or the kernels are getting worse at handling small amounts of RAM. I am going to try and define a more conclusive test, but that's teh current status.