linux-kernel - Re: [PATCH v2] page cache: Store only head pages in i

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Message-ID: <20190214133004.js7s42igiqc5pgwf@kshutemo-mobl1>
Date:   Thu, 14 Feb 2019 16:30:04 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, Hugh Dickins <hughd@...gle.com>,
        William Kucharski <william.kucharski@...cle.com>
Subject: Re: [PATCH v2] page cache: Store only head pages in i_pages

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@linux.intel.com/
> 
> Signed-off-by: Matthew Wilcox <willy@...radead.org>

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