aix7xxx in 2.5.53

It is bouncing. The machine has 7G of memory, was booted with mem=4G. The kernel was compiled with CONFIG_HIGHMEM4G.

c01304e8 115      0.0992971   buffered_rmqueue
c0146fc4 115      0.0992971   __find_get_block
c01602e4 126      0.108795    mpage_writepages
c012d5d4 147      0.126928    unlock_page
c0135554 151      0.130381    shrink_cache
c01892e8 170      0.146787    ext2_get_block
c0136c7c 173      0.149377    set_page_address
c0111930 184      0.158875    mark_offset_tsc
c0136be0 212      0.183052    page_address
c01d8418 2971     2.56532     __copy_from_user
c01369a4 3790     3.27249     __blk_queue_bounce
c01089f8 104325   90.0798     poll_idle