I have an alternate patch for low memory circumstances that I'd like you
to test out.
The problem with the old kswapd setup was at least partly that kswapd was
woken up too late - by the time kswapd was woken up, it really had to work
fairly hard. Also, kswapd really shouldn't be real-time at all: normally
it should just be a fairly low-priority process, and the priority should
grow as there is more urgent need for memory.
This alternate approach seems to work for me, and is designed to avoid the
"spikes" of heavy real-time kswapd activity during which the machine is
fairly unusable in the old scheme.

                Linus