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

From: Kirill A. Shutemov
Date: Thu Feb 14 2019 - 17:41:23 EST


On Thu, Feb 14, 2019 at 04:30:04PM +0300, Kirill A. Shutemov wrote:
> 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.

- __delete_from_swap_cache() will blow up on

VM_BUG_ON_PAGE(entry != page + i, entry);

--
Kirill A. Shutemov