FSCache causing "bad page state" kernel panics on RHEL6

Issue

• We have RHEL6.2 systems with fscache enabled, and experienced regular kernel panics until we disabled fscache.
• Our RHEL6 systems frequently hang. There is a crash in drop_buffers or try_to_free_buffers with the fscache module loaded.

kernel BUG at fs/buffer.c:3238!
invalid opcode: 0000 [#1] SMP 
last sysfs file: /sys/devices/system/cpu/cpu7/cache/index2/shared_cpu_map
CPU 0 

Pid: PID, comm: processname Tainted: G    B      ---------------- T 2.6.32-220.13.1.el6.x86_64 #1
RIP: 0010:[<ffffffff811a825b>]  [<ffffffff811a825b>] drop_buffers+0xbb/0xc0
...
Call Trace:
 [<ffffffff811a8309>] try_to_free_buffers+0xa9/0xc0