What are chunky pages?

What kinds of pages are categorized into unmovable pages and movable pages in Linux Kernel?

• For unmovable pages please be specific like kernel kmalloc, or vmalloc or all types of kernel pages, or Page cache pages ? Also, what all pages comes in category of MOVABLE PAGES(MIGRATE_MOVABLE) ?: Is it all page cache pages, user malloc pages mmaped pages ? Few things which I want to confirm other than answers to above Q. 1. All pages allocated for page tables are unmovable pages. 2. Pages which are allocated using GFP_ATOMIC are unmovable pages. 3. can user do pinned pages allocation which becomes unmovable ? How to do this.

• Answer:

  MOVABLE_PAGES: Those pages which are address though a layer of indirection and which are not otherwise pinned down are movable. So most user-space pages which are accesses using virtual addresses can be moved -> All we need to do is to tweak the relevant page table entries accordingly. UNMOVABLE_PAGES: Now, most memory used by kernel directly cannot be moved- though some of it is reclaimable, meaning that it can be freed entriely on demand. But even I am not entriely sure how to use pinned pages, and which kernel memory is set as reclaimable memory. Good if or some expert in linux kernel answer this question.