kswapd in D uninterruptible sleep on 2.4.21-pre3-ac2

I've got an SMP system running 2.4.21-pre3-ac2 with some odd behavior. It's basically completely idle, but with a load average of 1.00, which I believe is due to "kswapd" being stuck in uninterruptible sleep:

040 D 0 7 1 0 75 0 - 0 down ? 00:00:00 kswapd

Can someone explain this behavior?

# free
            total       used       free     shared    buffers     cached
Mem:       2069940     300504    1769436          0     100804      48020
-/+ buffers/cache:     151680    1918260
Swap:      2096472       1204    2095268

Thank you,

Orion Poplawski