The latest CVS check-in fixes a potential corruption at CFS server due to recursion. The bug was CFS inherited the backing device info of the backing file system. The Linux VM is re-entrant at balance_dirty_pages() and can call CFS recursively when the backing device info are the same on both file systems.
CFS -> VM -> PFS -> VM -> CFS -> VM -> PFS ...
The Linux VM may not call this far down and may not traverse file systems exactly as shown but if this happens you may get stack overflow, etc.
The fix should increase interactiveness and decrease latency since the VM no longer makes recursive calls at balance_dirty_pages().