From: Matthew Wilcox <willy@infradead.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, Hugh Dickins <hughd@google.com>,
William Kucharski <william.kucharski@oracle.com>
Subject: Re: [PATCH v2] page cache: Store only head pages in i_pages
Date: Fri, 15 Feb 2019 12:28:58 -0800 [thread overview]
Message-ID: <20190215202858.GL12668@bombadil.infradead.org> (raw)
In-Reply-To: <20190214222944.74ipvbnvo2lvfgnr@kshutemo-mobl1>
On Fri, Feb 15, 2019 at 01:29:44AM +0300, Kirill A. Shutemov wrote:
> 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@linux.intel.com/
> > >
> > > Signed-off-by: Matthew Wilcox <willy@infradead.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.
>
> Other missing pieces are memfd_wait_for_pins() and memfd_tag_pins()
> We need to call page_mapcount() for tail pages there.
@@ -39,6 +39,7 @@ static void memfd_tag_pins(struct xa_state *xas)
xas_for_each(xas, page, ULONG_MAX) {
if (xa_is_value(page))
continue;
+ page = find_subpage(page, xas.xa_index);
if (page_count(page) - page_mapcount(page) > 1)
xas_set_mark(xas, MEMFD_TAG_PINNED);
@@ -88,6 +89,7 @@ static int memfd_wait_for_pins(struct address_space *mapping)
bool clear = true;
if (xa_is_value(page))
continue;
+ page = find_subpage(page, xas.xa_index);
if (page_count(page) - page_mapcount(page) != 1) {
/*
* On the last scan, we clean up all those tags
next prev parent reply other threads:[~2019-02-15 20:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 18:34 [PATCH v2] page cache: Store only head pages in i_pages Matthew Wilcox
2019-02-13 14:41 ` Jan Kara
2019-02-13 20:17 ` Matthew Wilcox
2019-02-14 16:27 ` Jan Kara
2019-02-14 13:30 ` Kirill A. Shutemov
2019-02-14 20:53 ` Matthew Wilcox
2019-02-14 22:03 ` Kirill A. Shutemov
2019-02-14 22:25 ` Matthew Wilcox
2019-02-14 21:17 ` Matthew Wilcox
2019-02-14 22:08 ` Kirill A. Shutemov
2019-02-14 22:11 ` Matthew Wilcox
2019-02-14 22:29 ` Kirill A. Shutemov
2019-02-14 22:29 ` Kirill A. Shutemov
2019-02-15 20:28 ` Matthew Wilcox [this message]
2019-02-14 22:41 ` Kirill A. Shutemov
2019-02-15 20:20 ` Matthew Wilcox
2019-02-15 21:17 ` Kirill A. Shutemov
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