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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Matthew Wilcox <willy@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	"Darrick J. Wong" <djwong@kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	David Howells <dhowells@redhat.com>
Subject: Re: Splitting struct page into multiple types - Was: re: Folio discussion recap -
Date: Tue, 19 Oct 2021 14:37:10 -0300	[thread overview]
Message-ID: <20211019173710.GI3686969@ziepe.ca> (raw)
In-Reply-To: <YW7uN2p8CihCDsln@moria.home.lan>

On Tue, Oct 19, 2021 at 12:11:35PM -0400, Kent Overstreet wrote:

> I have no idea if this approach works for network pool pages or how those would
> be used, I haven't gotten that far - if someone can chime in about those that

Generally the driver goal is to create a shared memory buffer between
kernel and user space.

The broadly two common patterns are to have userspace call mmap() and
the kernel side returns the kernel pages from there - getting them
from some kernel allocator.

Or, userspace allocates the buffer and the kernel driver does
pin_user_pages() to import them to its address space.

I think it is quite feasible to provide some simple library API to
manage the shared buffer through mmap approach, and if that library
wants to allocate inodes, folios and what not it should be possible.

It would help this idea to see Christoph's cleanup series go forward:

https://lore.kernel.org/all/20200508153634.249933-1-hch@lst.de/

As it makes it alot easier for drivers to get inodes in the first
place.

> would be great. But, the end goal I'm envisioning is a world where _only_ bog
> standard file & anonymous pages are mapped to userspace - then _mapcount can be
> deleted from struct page and only needs to live in struct folio.

There is a lot of work in the past years on ZONE_DEVICE pages into
userspace. Today FSDAX is kind of a mashup of a file and device page,
but other stuff is less obvious, especially DEVICE_COHERENT.

Jason

  parent reply	other threads:[~2021-10-19 17:37 UTC|newest]

Thread overview: 162+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23 19:01 [GIT PULL] Memory folios for v5.15 Matthew Wilcox
2021-08-23 21:26 ` Johannes Weiner
2021-08-23 22:06   ` Linus Torvalds
2021-08-24  2:20     ` Matthew Wilcox
2021-08-24 13:04     ` Matthew Wilcox
2021-08-23 22:15   ` Matthew Wilcox
2021-08-24 18:32     ` Johannes Weiner
2021-08-24 18:59       ` Linus Torvalds
2021-08-25  6:39         ` Christoph Hellwig
2021-08-24 19:44       ` Matthew Wilcox
2021-08-25 15:13         ` Johannes Weiner
2021-08-26  0:45           ` Darrick J. Wong
2021-08-27 14:07             ` Johannes Weiner
2021-08-27 18:44               ` Matthew Wilcox
2021-08-27 21:41                 ` Dan Williams
2021-08-27 21:49                   ` Matthew Wilcox
2021-08-30 17:32                 ` Johannes Weiner
2021-08-30 18:22                   ` Matthew Wilcox
2021-08-30 20:27                     ` Johannes Weiner
2021-08-30 21:38                       ` Matthew Wilcox
2021-08-31 17:40                         ` Vlastimil Babka
2021-09-01 17:43                         ` Johannes Weiner
2021-09-02 15:13                           ` Zi Yan
2021-09-06 14:00                             ` Vlastimil Babka
2021-08-31 18:50                       ` Eric W. Biederman
2021-08-26  8:58         ` David Howells
2021-08-27 10:03           ` Johannes Weiner
2021-08-27 12:05             ` Matthew Wilcox
2021-08-27 10:49           ` David Howells
2021-08-24 15:54   ` David Howells
2021-08-24 17:56     ` Matthew Wilcox
2021-08-24 18:26       ` Linus Torvalds
2021-08-24 18:29         ` Linus Torvalds
2021-08-24 19:26           ` Theodore Ts'o
2021-08-24 19:34           ` David Howells
2021-08-24 20:02             ` Theodore Ts'o
2021-08-24 21:32             ` David Howells
2021-08-25 12:08               ` Jeff Layton
2021-08-24 19:01         ` Matthew Wilcox
2021-08-24 19:11           ` Linus Torvalds
2021-08-24 19:23             ` Matthew Wilcox
2021-08-24 19:44               ` Theodore Ts'o
2021-08-24 20:00                 ` Matthew Wilcox
2021-08-25  6:32                 ` Christoph Hellwig
2021-08-25  9:01                   ` Rasmus Villemoes
2021-08-26  6:32                     ` Amir Goldstein
2021-08-25 12:03                   ` Jeff Layton
2021-08-26  0:59                     ` Darrick J. Wong
2021-08-26  4:02                   ` Nicholas Piggin
2021-09-01 12:58                 ` Mike Rapoport
2021-08-24 19:35             ` David Howells
2021-08-24 20:35               ` Vlastimil Babka
2021-08-24 20:40                 ` Vlastimil Babka
2021-08-24 19:11         ` David Howells
2021-08-24 19:25           ` Linus Torvalds
2021-08-24 19:38             ` Linus Torvalds
2021-08-24 19:48               ` Linus Torvalds
2021-08-26 17:18                 ` Matthew Wilcox
2021-08-24 19:59             ` David Howells
2021-10-05 13:52   ` Matthew Wilcox
2021-10-05 17:29     ` Johannes Weiner
2021-10-05 17:32       ` David Hildenbrand
2021-10-05 18:30       ` Matthew Wilcox
2021-10-05 19:56         ` Jason Gunthorpe
2021-08-28  3:29 ` Matthew Wilcox
2021-09-09 12:43 ` Christoph Hellwig
2021-09-09 13:56   ` Vlastimil Babka
2021-09-09 18:16     ` Johannes Weiner
2021-09-09 18:44       ` Matthew Wilcox
2021-09-09 22:03         ` Johannes Weiner
2021-09-09 22:48           ` Matthew Wilcox
2021-09-09 19:17     ` John Hubbard
2021-09-09 19:23       ` Matthew Wilcox
2021-09-10 20:16 ` Folio discussion recap Kent Overstreet
2021-09-11  1:23   ` Kirill A. Shutemov
2021-09-13 11:32     ` Michal Hocko
2021-09-13 18:12       ` Johannes Weiner
2021-09-15 15:40   ` Johannes Weiner
2021-09-15 17:55     ` Damian Tometzki
2021-09-16  2:58     ` Darrick J. Wong
2021-09-16 16:54       ` Johannes Weiner
2021-09-17  5:24         ` Dave Chinner
2021-09-17  7:18           ` Christoph Hellwig
2021-09-17 16:31           ` Johannes Weiner
2021-09-17 20:57             ` Kirill A. Shutemov
2021-09-17 21:17               ` Kent Overstreet
2021-09-17 22:02                 ` Kirill A. Shutemov
2021-09-17 22:21                   ` Kent Overstreet
2021-09-17 23:15               ` Johannes Weiner
2021-09-20 10:03                 ` Kirill A. Shutemov
2021-09-17 21:13             ` Kent Overstreet
2021-09-17 22:25               ` Theodore Ts'o
2021-09-17 23:35                 ` Josef Bacik
2021-09-18  1:04             ` Dave Chinner
2021-09-18  4:51               ` Kent Overstreet
2021-09-20  1:04                 ` Dave Chinner
2021-09-16 21:58       ` David Howells
2021-09-20  2:17   ` Matthew Wilcox
2021-09-21 19:47     ` Johannes Weiner
2021-09-21 20:38       ` Matthew Wilcox
2021-09-21 21:11         ` Kent Overstreet
2021-09-21 21:22           ` Folios for 5.15 request - Was: re: Folio discussion recap - Kent Overstreet
2021-09-22 15:08             ` Johannes Weiner
2021-09-22 15:46               ` Kent Overstreet
2021-09-22 16:26                 ` Matthew Wilcox
2021-09-22 16:56                   ` Chris Mason
2021-09-22 19:54                     ` Matthew Wilcox
2021-09-22 20:15                       ` Kent Overstreet
2021-09-22 20:21                       ` Linus Torvalds
2021-09-23  5:42               ` Kent Overstreet
2021-09-23 18:00                 ` Johannes Weiner
2021-09-23 19:31                   ` Matthew Wilcox
2021-09-23 20:20                   ` Kent Overstreet
2021-10-16  3:28               ` Matthew Wilcox
2021-10-18 16:47                 ` Johannes Weiner
2021-10-18 18:12                   ` Kent Overstreet
2021-10-18 20:45                     ` Johannes Weiner
2021-10-19 16:11                       ` Splitting struct page into multiple types " Kent Overstreet
2021-10-19 17:06                         ` Gao Xiang
2021-10-19 17:34                           ` Matthew Wilcox
2021-10-19 17:54                             ` Gao Xiang
2021-10-20 17:46                               ` Kent Overstreet
2021-10-19 17:37                         ` Jason Gunthorpe [this message]
2021-10-19 21:14                       ` David Howells
2021-10-18 18:28                   ` Folios for 5.15 request " Matthew Wilcox
2021-10-18 21:56                     ` Johannes Weiner
2021-10-18 23:16                       ` Kirill A. Shutemov
2021-10-19 15:16                         ` Johannes Weiner
2021-10-20  3:19                           ` Matthew Wilcox
2021-10-20  7:50                           ` David Hildenbrand
2021-10-20 17:26                             ` Matthew Wilcox
2021-10-20 18:04                               ` David Hildenbrand
2021-10-21  6:51                                 ` Christoph Hellwig
2021-10-21  7:21                                   ` David Hildenbrand
2021-10-21 12:03                                     ` Kent Overstreet
2021-10-21 12:35                                       ` David Hildenbrand
2021-10-21 12:38                                         ` Christoph Hellwig
2021-10-21 13:00                                           ` David Hildenbrand
2021-10-21 12:41                                         ` Matthew Wilcox
2021-10-20 17:39                           ` Kent Overstreet
2021-10-21 21:37                             ` Johannes Weiner
2021-10-22  1:52                               ` Matthew Wilcox
2021-10-22  7:59                                 ` David Hildenbrand
2021-10-22 13:01                                   ` Matthew Wilcox
2021-10-22 14:40                                     ` David Hildenbrand
2021-10-23  2:22                                       ` Matthew Wilcox
2021-10-23  5:02                                         ` Christoph Hellwig
2021-10-23  9:58                                         ` David Hildenbrand
2021-10-23 16:00                                           ` Kent Overstreet
2021-10-23 21:41                                             ` Matthew Wilcox
2021-10-23 22:23                                               ` Kent Overstreet
2021-10-25 15:35                                 ` Johannes Weiner
2021-10-25 15:52                                   ` Matthew Wilcox
2021-10-25 16:05                                   ` Kent Overstreet
2021-10-16 19:07               ` Matthew Wilcox
2021-10-18 17:25                 ` Johannes Weiner
2021-09-21 22:18           ` Folio discussion recap Matthew Wilcox
2021-09-23  0:45             ` Ira Weiny
2021-09-23  3:41               ` Matthew Wilcox
2021-09-23 22:12                 ` Ira Weiny
2021-09-29 15:24                   ` Matthew Wilcox
2021-09-21 21:59         ` Johannes Weiner

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