Kernel Memory Compaction option turned off by default on WRT3200ACM

I've been working through a memory exhaustion issue on Trunk builds. Digging around in the kernel_menuconfig, I came across the Allow for memory compaction option, which is turned off when the WRT3200ACM build is selected.

The help text says the following:

Compaction is the only memory management component to form high order (larger physically contiguous) memory blocks reliably. The page allocator relies on compaction heavily and the lack of the feature can lead to unexpected OOM killer invocations for high order memory requests. You shouldn't disable this option unless there really is a strong reason for it and then we would be really interested to hear about that at

Given the above commentary, does anyone know why this option would be turned-off when this platform is selected?