Re: [PATCH v6 00/27] Memory Folios

[Matthew Wilcox]

On Thu, Apr 01, 2021 at 08:05:37AM +0100, Christoph Hellwig wrote:
> On Wed, Mar 31, 2021 at 07:47:01PM +0100, Matthew Wilcox (Oracle) wrote:
> >  - Mirror members of struct page (for pagecache / anon) into struct folio,
> >    so (eg) you can use folio->mapping instead of folio->page.mapping
> 
> Eww, why?

So that eventually we can rename page->mapping to page->_mapping and
prevent the bugs from people doing page->mapping on a tail page.  eg
https://lore.kernel.org/linux-mm/alpine.LSU.2.11.2103102214170.7159@eggly.anvils/