Hi,
Here is a set of well-reviewed (expect for one patch), lower-risk items that can go into Linux 5.5. The one patch that wasn't reviewed is the powerpc conversion, and it's still at this point a no-op, because tracking isn't yet activated.
This is based on linux-next: b9d3d01405061bb42358fe53f824e894a1922ced ("Add linux-next specific files for 20191122").
This is essentially a cut-down v8 of "mm/gup: track dma-pinned pages: FOLL_PIN" [1], and with one of the VFIO patches split into two patches. The idea here is to get this long list of "noise" checked into 5.5, so that the actual, higher-risk "track FOLL_PIN pages" (which is deferred: not part of this series) will be a much shorter patchset to review.
For the v4l2-core changes, I've left those here (instead of sending them separately to the -media tree), in order to get the name change done now (put_user_page --> unpin_user_page). However, I've added a Cc stable, as recommended during the last round of reviews.
Here are the relevant notes from the original cover letter, edited to match the current situation:
This is a prerequisite to tracking dma-pinned pages. That in turn 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()
[1] https://lore.kernel.org/r/20191121071354.456618-1-jhubbard@nvidia.com
thanks, John Hubbard NVIDIA
Dan Williams (1): mm: Cleanup __put_devmap_managed_page() vs ->page_free()
John Hubbard (18): mm/gup: factor out duplicate code from four routines mm/gup: move try_get_compound_head() to top, fix minor issues goldish_pipe: rename local pin_user_pages() routine mm: fix get_user_pages_remote()'s handling of FOLL_LONGTERM vfio: fix FOLL_LONGTERM use, simplify get_user_pages_remote() call mm/gup: introduce pin_user_pages*() and FOLL_PIN goldish_pipe: convert to pin_user_pages() and put_user_page() IB/{core,hw,umem}: set FOLL_PIN via pin_user_pages*(), fix up ODP 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() media/v4l2-core: set pages dirty upon releasing DMA buffers media/v4l2-core: pin_user_pages (FOLL_PIN) and put_user_page() conversion vfio, mm: pin_user_pages (FOLL_PIN) and put_user_page() conversion powerpc: book3s64: convert to pin_user_pages() and put_user_page() mm/gup_benchmark: use proper FOLL_WRITE flags instead of hard-coding "1" mm, tree-wide: rename put_user_page*() to unpin_user_page*()
Documentation/core-api/index.rst | 1 + Documentation/core-api/pin_user_pages.rst | 233 ++++++++++++++ arch/powerpc/mm/book3s64/iommu_api.c | 12 +- drivers/gpu/drm/via/via_dmablit.c | 6 +- drivers/infiniband/core/umem.c | 4 +- drivers/infiniband/core/umem_odp.c | 13 +- drivers/infiniband/hw/hfi1/user_pages.c | 4 +- drivers/infiniband/hw/mthca/mthca_memfree.c | 8 +- drivers/infiniband/hw/qib/qib_user_pages.c | 4 +- drivers/infiniband/hw/qib/qib_user_sdma.c | 8 +- drivers/infiniband/hw/usnic/usnic_uiom.c | 4 +- drivers/infiniband/sw/siw/siw_mem.c | 4 +- drivers/media/v4l2-core/videobuf-dma-sg.c | 8 +- drivers/nvdimm/pmem.c | 6 - drivers/platform/goldfish/goldfish_pipe.c | 35 +-- drivers/vfio/vfio_iommu_type1.c | 35 +-- fs/io_uring.c | 6 +- include/linux/mm.h | 77 +++-- mm/gup.c | 332 +++++++++++++------- mm/gup_benchmark.c | 9 +- mm/memremap.c | 80 ++--- mm/process_vm_access.c | 28 +- net/xdp/xdp_umem.c | 4 +- tools/testing/selftests/vm/gup_benchmark.c | 6 +- 24 files changed, 642 insertions(+), 285 deletions(-) create mode 100644 Documentation/core-api/pin_user_pages.rst