[$] Triggering huge-page collapse from user space

When the kernel first gained support forhuge pages, most of the work was left to user space. System administratorshad to set aside memory in the special hugetlbfs filesystem for huge pages, andprograms had to explicitly map memory from there. Over time, the transparent huge pages mechanism automated thetask of using huge pages. That mechanism is not perfect, though, and someusers feel that they have better knowledge of when huge-page use makes sensefor a given process. Thus, huge pages are now coming full circle with this patchset from Zach O'Keefe returning huge pages to user-space control.