Lockups during large copies

[Eugene Gluzberg]

I am running latest Gentoo on my AMD 64 machine, in 64 bit mode. My
primary disk is on a SIL fakeraid on 2 mirrored sata disks. I am running
device mapper, udev, and dmraid. have my root partition using reiserfs
(version 3). When I do large cp operations (like copying a 2GB file), my
system locks - slowly. Like over several minutes the system becomes less
and less responsive, as if the load or memory use is rising until it
finally locks up completely. This problem is reproduceble. A hardware
reboot is needed every time. There is no messages in the kernel log that
indicate the problem. Has anyone seen this? How do I investigate it?

2.6.11-gentoo-r6
x86_64 AMD Athlon(tm) 64 Processor 3200+ AuthenticAMD