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From: John Hubbard <jhubbard@nvidia.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Al Viro" <viro@zeniv.linux.org.uk>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Dave Chinner" <david@fromorbit.com>,
	"David Airlie" <airlied@linux.ie>,
	"David S . Miller" <davem@davemloft.net>,
	"Ira Weiny" <ira.weiny@intel.com>, "Jan Kara" <jack@suse.cz>,
	"Jason Gunthorpe" <jgg@ziepe.ca>, "Jens Axboe" <axboe@kernel.dk>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Michal Hocko" <mhocko@suse.com>,
	"Mike Kravetz" <mike.kravetz@oracle.com>,
	"Paul Mackerras" <paulus@samba.org>,
	"Shuah Khan" <shuah@kernel.org>,
	"Vlastimil Babka" <vbabka@suse.cz>,
	bpf@vger.kernel.org, dri-devel@lists.freedesktop.org,
	kvm@vger.kernel.org, linux-block@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org,
	linux-rdma@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	netdev@vger.kernel.org, linux-mm@kvack.org,
	LKML <linux-kernel@vger.kernel.org>,
	"John Hubbard" <jhubbard@nvidia.com>
Subject: [PATCH 00/19] mm/gup: track dma-pinned pages: FOLL_PIN, FOLL_LONGTERM
Date: Wed, 30 Oct 2019 15:49:11 -0700	[thread overview]
Message-ID: <20191030224930.3990755-1-jhubbard@nvidia.com> (raw)

Hi,

This applies cleanly to linux-next and mmotm, and also to linux.git if
linux-next's commit 20cac10710c9 ("mm/gup_benchmark: fix MAP_HUGETLB
case") is first applied there.

This provides tracking of dma-pinned pages. This is a prerequisite to
solving the larger problem of proper interactions between file-backed
pages, and [R]DMA activities, as discussed in [1], [2], [3], and in
a remarkable number of email threads since about 2017. :)

A new internal gup flag, FOLL_PIN is introduced, and thoroughly
documented in the last patch's Documentation/vm/pin_user_pages.rst.

I believe that this will provide a good starting point for doing the
layout lease work that Ira Weiny has been working on. That's because
these new wrapper functions provide a clean, constrained, systematically
named set of functionality that, again, is required in order to even
know if a page is "dma-pinned".

In contrast to earlier approaches, the page tracking can be
incrementally applied to the kernel call sites that, until now, have
been simply calling get_user_pages() ("gup"). In other words, opt-in by
changing from this:

    get_user_pages() (sets FOLL_GET)
    put_page()

to this:
    pin_user_pages() (sets FOLL_PIN)
    put_user_page()

Because there are interdependencies with FOLL_LONGTERM, a similar
conversion as for FOLL_PIN, was applied. The change was from this:

    get_user_pages(FOLL_LONGTERM) (also sets FOLL_GET)
    put_page()

to this:
    pin_longterm_pages() (sets FOLL_PIN | FOLL_LONGTERM)
    put_user_page()

============================================================
Patch summary:

* Patches 1-4: refactoring and preparatory cleanup, independent fixes
    (Patch 4: V4L2-core bug fix (can be separately applied))

* Patch 5: introduce pin_user_pages(), FOLL_PIN, but no functional
           changes yet
* Patches 6-11: Convert existing put_user_page() callers, to use the
                new pin*()
* Patch 12: Activate tracking of FOLL_PIN pages.
* Patches 13-15: convert FOLL_LONGTERM callers
* Patches: 16-17: gup_benchmark and run_vmtests support
* Patch 18: enforce FOLL_LONGTERM as a gup-internal (only) flag
* Patch 19: Documentation/vm/pin_user_pages.rst

============================================================
Testing:

* I've done some overall kernel testing (LTP, and a few other goodies),
  and some directed testing to exercise some of the changes. And as you
  can see, gup_benchmark is enhanced to exercise this. Basically, I've been
  able to runtime test the core get_user_pages() and pin_user_pages() and
  related routines, but not so much on several of the call sites--but those
  are generally just a couple of lines changed, each.

  Not much of the kernel is actually using this, which on one hand
  reduces risk quite a lot. But on the other hand, testing coverage
  is low. So I'd love it if, in particular, the Infiniband and PowerPC
  folks could do a smoke test of this series for me.

  Also, my runtime testing for the call sites so far is very weak:

    * io_uring: Some directed tests from liburing exercise this, and they pass.
    * process_vm_access.c: A small directed test passes.
    * gup_benchmark: the enhanced version hits the new gup.c code, and passes.
    * infiniband (still only have crude "IB pingpong" working, on a
                  good day: it's not exercising my conversions at runtime...)
    * VFIO: compiles (I'm vowing to set up a run time test soon, but it's
                      not ready just yet)
    * powerpc: it compiles...
    * drm/via: compiles...
    * goldfish: compiles...
    * net/xdp: compiles...
    * media/v4l2: compiles...

============================================================
Next:

* Get the block/bio_vec sites converted to use pin_user_pages().

* Work with Ira and Dave Chinner to weave this together with the
  layout lease stuff.

============================================================

[1] Some slow progress on get_user_pages() (Apr 2, 2019): https://lwn.net/Articles/784574/
[2] DMA and get_user_pages() (LPC: Dec 12, 2018): https://lwn.net/Articles/774411/
[3] The trouble with get_user_pages() (Apr 30, 2018): https://lwn.net/Articles/753027/

John Hubbard (19):
  mm/gup: pass flags arg to __gup_device_* functions
  mm/gup: factor out duplicate code from four routines
  goldish_pipe: rename local pin_user_pages() routine
  media/v4l2-core: set pages dirty upon releasing DMA buffers
  mm/gup: introduce pin_user_pages*() and FOLL_PIN
  goldish_pipe: convert to pin_user_pages() and put_user_page()
  infiniband: set FOLL_PIN, FOLL_LONGTERM via pin_longterm_pages*()
  mm/process_vm_access: set FOLL_PIN via pin_user_pages_remote()
  drm/via: set FOLL_PIN via pin_user_pages_fast()
  fs/io_uring: set FOLL_PIN via pin_user_pages()
  net/xdp: set FOLL_PIN via pin_user_pages()
  mm/gup: track FOLL_PIN pages
  media/v4l2-core: pin_longterm_pages (FOLL_PIN) and put_user_page()
    conversion
  vfio, mm: pin_longterm_pages (FOLL_PIN) and put_user_page() conversion
  powerpc: book3s64: convert to pin_longterm_pages() and put_user_page()
  mm/gup_benchmark: support pin_user_pages() and related calls
  selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN
    coverage
  mm/gup: remove support for gup(FOLL_LONGTERM)
  Documentation/vm: add pin_user_pages.rst

 Documentation/vm/index.rst                  |   1 +
 Documentation/vm/pin_user_pages.rst         | 213 +++++++
 arch/powerpc/mm/book3s64/iommu_api.c        |  15 +-
 drivers/gpu/drm/via/via_dmablit.c           |   2 +-
 drivers/infiniband/core/umem.c              |   5 +-
 drivers/infiniband/core/umem_odp.c          |  10 +-
 drivers/infiniband/hw/hfi1/user_pages.c     |   4 +-
 drivers/infiniband/hw/mthca/mthca_memfree.c |   3 +-
 drivers/infiniband/hw/qib/qib_user_pages.c  |   8 +-
 drivers/infiniband/hw/qib/qib_user_sdma.c   |   2 +-
 drivers/infiniband/hw/usnic/usnic_uiom.c    |   9 +-
 drivers/infiniband/sw/siw/siw_mem.c         |   5 +-
 drivers/media/v4l2-core/videobuf-dma-sg.c   |  10 +-
 drivers/platform/goldfish/goldfish_pipe.c   |  35 +-
 drivers/vfio/vfio_iommu_type1.c             |  15 +-
 fs/io_uring.c                               |   5 +-
 include/linux/mm.h                          | 133 ++++-
 include/linux/mmzone.h                      |   2 +
 include/linux/page_ref.h                    |  10 +
 mm/gup.c                                    | 622 ++++++++++++++++----
 mm/gup_benchmark.c                          |  81 ++-
 mm/huge_memory.c                            |  32 +-
 mm/hugetlb.c                                |  28 +-
 mm/memremap.c                               |   4 +-
 mm/process_vm_access.c                      |  28 +-
 mm/vmstat.c                                 |   2 +
 net/xdp/xdp_umem.c                          |   4 +-
 tools/testing/selftests/vm/gup_benchmark.c  |  28 +-
 tools/testing/selftests/vm/run_vmtests      |  22 +
 29 files changed, 1066 insertions(+), 272 deletions(-)
 create mode 100644 Documentation/vm/pin_user_pages.rst

-- 
2.23.0


             reply	other threads:[~2019-10-30 22:53 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-30 22:49 John Hubbard [this message]
2019-10-30 22:49 ` [PATCH 01/19] mm/gup: pass flags arg to __gup_device_* functions John Hubbard
2019-10-31 18:18   ` Ira Weiny
2019-10-30 22:49 ` [PATCH 02/19] mm/gup: factor out duplicate code from four routines John Hubbard
2019-10-31 18:35   ` Ira Weiny
2019-10-31 18:43     ` John Hubbard
2019-10-31 21:09       ` Ira Weiny
2019-10-31 22:01         ` John Hubbard
2019-10-30 22:49 ` [PATCH 03/19] goldish_pipe: rename local pin_user_pages() routine John Hubbard
2019-10-31 18:36   ` Ira Weiny
2019-10-30 22:49 ` [PATCH 04/19] media/v4l2-core: set pages dirty upon releasing DMA buffers John Hubbard
2019-10-30 22:49 ` [PATCH 05/19] mm/gup: introduce pin_user_pages*() and FOLL_PIN John Hubbard
2019-10-31 23:15   ` Ira Weiny
2019-10-31 23:43     ` John Hubbard
2019-10-30 22:49 ` [PATCH 06/19] goldish_pipe: convert to pin_user_pages() and put_user_page() John Hubbard
2019-10-30 22:49 ` [PATCH 07/19] infiniband: set FOLL_PIN, FOLL_LONGTERM via pin_longterm_pages*() John Hubbard
2019-10-31 23:25   ` Ira Weiny
2019-10-31 23:49     ` John Hubbard
2019-10-30 22:49 ` [PATCH 08/19] mm/process_vm_access: set FOLL_PIN via pin_user_pages_remote() John Hubbard
2019-10-31 23:35   ` Ira Weiny
2019-10-31 23:46     ` John Hubbard
2019-10-30 22:49 ` [PATCH 09/19] drm/via: set FOLL_PIN via pin_user_pages_fast() John Hubbard
2019-10-31 23:36   ` Ira Weiny
2019-11-04 18:10     ` Daniel Vetter
2019-11-04 19:20       ` John Hubbard
2019-11-05  9:49         ` Daniel Vetter
2019-11-05 18:16           ` John Hubbard
2019-10-30 22:49 ` [PATCH 10/19] fs/io_uring: set FOLL_PIN via pin_user_pages() John Hubbard
2019-10-31 23:37   ` Ira Weiny
2019-11-01 14:49   ` Jens Axboe
2019-10-30 22:49 ` [PATCH 11/19] net/xdp: " John Hubbard
2019-10-31 23:37   ` Ira Weiny
2019-11-02 11:01   ` Björn Töpel
2019-10-30 22:49 ` [PATCH 12/19] mm/gup: track FOLL_PIN pages John Hubbard
2019-10-30 22:49 ` [PATCH 13/19] media/v4l2-core: pin_longterm_pages (FOLL_PIN) and put_user_page() conversion John Hubbard
2019-10-31 23:38   ` Ira Weiny
2019-10-30 22:49 ` [PATCH 14/19] vfio, mm: " John Hubbard
2019-10-30 23:05   ` John Hubbard
2019-10-30 22:49 ` [PATCH 15/19] powerpc: book3s64: convert to pin_longterm_pages() and put_user_page() John Hubbard
2019-10-30 22:49 ` [PATCH 16/19] mm/gup_benchmark: support pin_user_pages() and related calls John Hubbard
2019-10-30 22:49 ` [PATCH 17/19] selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage John Hubbard
2019-10-30 22:49 ` [PATCH 18/19] mm/gup: remove support for gup(FOLL_LONGTERM) John Hubbard
2019-10-30 22:49 ` [PATCH 19/19] Documentation/vm: add pin_user_pages.rst John Hubbard
2019-10-31 23:49   ` Ira Weiny
2019-10-31 23:53     ` John Hubbard
2019-11-01  0:48     ` John Hubbard
2019-11-03 19:53   ` John Hubbard

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