hugetlb_get_unmapped_area() fails to find an unmapped area while unmapped
area is huge.  That's because hugetlb_get_unmapped_area just searches
forward from mm->free_area_cache.  If reaching TASK_SIZE, it does not go
back to TASK_UNMAPPED_BASE, just returns -ENOMEM.

1) Add a specific hugetlb_get_unmapped_area on i386.
2) Generic hugetlb_get_unmapped_area is also fixed.
Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>