Re: [PATCH v2] page cache: Store only head pages in i_pages

[Kirill A. Shutemov]

On Tue, Feb 12, 2019 at 10:34:54AM -0800, Matthew Wilcox wrote:
> Transparent Huge Pages are currently stored in i_pages as pointers to
> consecutive subpages.  This patch changes that to storing consecutive
> pointers to the head page in preparation for storing huge pages more
> efficiently in i_pages.
> 
> Large parts of this are "inspired" by Kirill's patch
> https://lore.kernel.org/lkml/20170126115819.58875-2-kirill.shutemov@xxxxxxxxxxxxxxx/
> 
> Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>

I believe I found few missing pieces:

 - page_cache_delete_batch() will blow up on

			VM_BUG_ON_PAGE(page->index + HPAGE_PMD_NR - tail_pages
					!= pvec->pages[i]->index, page);

 - migrate_page_move_mapping() has to be converted too.

The rest *looks* fine to me. But it needs a lot of testing.

-- 
 Kirill A. Shutemov