From patchwork Mon Dec 16 22:25:12 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11295981 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8CB616C1 for ; Mon, 16 Dec 2019 22:30:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 603BD22464 for ; Mon, 16 Dec 2019 22:30:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="rzU7HVYF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727689AbfLPWZm (ORCPT ); Mon, 16 Dec 2019 17:25:42 -0500 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:11884 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727438AbfLPWZl (ORCPT ); Mon, 16 Dec 2019 17:25:41 -0500 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 16 Dec 2019 14:25:31 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 16 Dec 2019 14:25:40 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 16 Dec 2019 14:25:40 -0800 Received: from HQMAIL109.nvidia.com (172.20.187.15) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 16 Dec 2019 22:25:39 +0000 Received: from HQMAIL101.nvidia.com (172.20.187.10) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 16 Dec 2019 22:25:39 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Mon, 16 Dec 2019 22:25:39 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Mon, 16 Dec 2019 14:25:39 -0800 From: John Hubbard To: Andrew Morton CC: Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?utf-8?b?QmrDtnJuIFQ=?= =?utf-8?b?w7ZwZWw=?= , Christoph Hellwig , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jason Gunthorpe , Jens Axboe , Jonathan Corbet , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Magnus Karlsson , "Mauro Carvalho Chehab" , Michael Ellerman , Michal Hocko , Mike Kravetz , "Paul Mackerras" , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML , John Hubbard Subject: [PATCH v11 00/25] mm/gup: track dma-pinned pages: FOLL_PIN Date: Mon, 16 Dec 2019 14:25:12 -0800 Message-ID: <20191216222537.491123-1-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1576535131; bh=kXZgebWOzv1eD/Ow2mzRQKWqAbiWjhBemb2nahCMdfs=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: MIME-Version:X-NVConfidentiality:Content-Type: Content-Transfer-Encoding; b=rzU7HVYFkQqLDEekcbNlZ7U9kWPrLZdc8v5rOtl3A/lvoezqPcu+V0KtJFNgfPPsc 6DHoc0ogw3MwkbgdOUoUJcEMpknUsr0Gy51jZVrUKOjsry7e+Ygpfzym1D5BUlG5oP 9puJA+Q5DJeVeEJ9McmJCEuT5wqguoEAHJcWyRSb4227weMCpnyLENCfFe2Lj0xD5o Qeb0SzZGjvV1Gttwrq9R/yC2rDSBuNXuDYyeHyAoDmYNjuGLcMW5R+xuGezgtVN86U uOfXfLZsswxEFeodfLwN8oAPQ1N7jhZH6+T3di/eHdxkJhuG6eh+wUZc4HbZF4xXvG VKc61q3+Yatpg== Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Hi, This implements an API naming change (put_user_page*() --> unpin_user_page*()), and also implements tracking of FOLL_PIN pages. It extends that tracking to a few select subsystems. More subsystems will be added in follow up work. Christoph Hellwig, a point of interest: a) I've moved the bulk of the code out of the inline functions, as requested, for the devmap changes (patch 4: "mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages"). Changes since v10: Remaining fixes resulting from Jan Kara's reviews: * Shifted to using the sign bit in page_dma_pinned() to allow accurate results even in the overflow case. See the comments in that routine for details. This allowed getting rid of the new page_ref_zero_or_close_to_bias_overflow(), in favor of a simple sign check via "page_ref_count() <= 0"). * Simplified some of the huge_memory.c changes, and simplified a gup.c WARN invocation. * Now using a standard -ENOMEM for most try_grab_page() failures. * Got rid of tabs in the comment headers (I had thought they were required there, but it's actually the reverse: they are not allowed there). * Rebased against 5.5-rc2 and retested. * Added Jan Kara's reviewed-by tag for patch 23 (the main patch of the series). Changes since v9: Fixes resulting from Jan Kara's and Jonathan Corbet's reviews: * Removed reviewed-by tags from the "mm/gup: track FOLL_PIN pages" (those were improperly inherited from the much smaller refactoring patch that was merged into it). * Made try_grab_compound_head() and try_grab_page() behavior similar in their behavior with flags, in order to avoid "gotchas" later. * follow_trans_huge_pmd(): moved the try_grab_page() to earlier in the routine, in order to avoid having to undo mlock_vma_page(). * follow_hugetlb_page(): removed a refcount overflow check that is now extraneous (and weaker than what try_grab_page() provides a few lines further down). * Fixed up two Documentation flaws, pointed out by Jonathan Corbet's review. Changes since v8: * Merged the "mm/gup: pass flags arg to __gup_device_* functions" patch into the "mm/gup: track FOLL_PIN pages" patch, as requested by Christoph and Jan. * Changed void grab_page() to bool try_grab_page(), and handled errors at the call sites. (From Jan's review comments.) try_grab_page() attempts to avoid page refcount overflows, even when counting up with GUP_PIN_COUNTING_BIAS increments. * Fixed a bug that I'd introduced, when changing a BUG() to a WARN(). * Added Jan's reviewed-by tag to the " mm/gup: allow FOLL_FORCE for get_user_pages_fast()" patch. * Documentation: pin_user_pages.rst: fixed an incorrect gup_benchmark invocation, left over from the pin_longterm days, spotted while preparing this version. * Rebased onto today's linux.git (-rc1), and re-tested. Changes since v7: * Rebased onto Linux 5.5-rc1 * Reworked the grab_page() and try_grab_compound_head(), for API consistency and less diffs (thanks to Jan Kara's reviews). * Added Leon Romanovsky's reviewed-by tags for two of the IB-related patches. * patch 4 refactoring changes, as mentioned above. There is a git repo and branch, for convenience: git@github.com:johnhubbard/linux.git pin_user_pages_tracking_v8 For the remaining list of "changes since version N", those are all in v7, which is here: https://lore.kernel.org/r/20191121071354.456618-1-jhubbard@nvidia.com ============================================================ Overview: This is a prerequisite to solving the 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) unpin_user_page() ============================================================ 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. Runtime testing for the call sites so far is pretty light: * 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: ran "ib_write_bw", which exercises the umem.c changes, but not the other changes. * 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... [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/ Dan Williams (1): mm: Cleanup __put_devmap_managed_page() vs ->page_free() John Hubbard (24): mm/gup: factor out duplicate code from four routines mm/gup: move try_get_compound_head() to top, fix minor issues mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages 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: allow FOLL_FORCE for get_user_pages_fast() IB/umem: use get_user_pages_fast() to pin DMA pages 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*() mm/gup: track FOLL_PIN pages mm/gup_benchmark: support pin_user_pages() and related calls selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage Documentation/core-api/index.rst | 1 + Documentation/core-api/pin_user_pages.rst | 232 ++++++++ arch/powerpc/mm/book3s64/iommu_api.c | 10 +- drivers/gpu/drm/via/via_dmablit.c | 6 +- drivers/infiniband/core/umem.c | 19 +- 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 | 155 ++++- include/linux/mmzone.h | 2 + include/linux/page_ref.h | 10 + mm/gup.c | 626 +++++++++++++++----- mm/gup_benchmark.c | 74 ++- mm/huge_memory.c | 29 +- mm/hugetlb.c | 38 +- mm/memremap.c | 76 ++- mm/process_vm_access.c | 28 +- mm/swap.c | 24 + mm/vmstat.c | 2 + net/xdp/xdp_umem.c | 4 +- tools/testing/selftests/vm/gup_benchmark.c | 21 +- tools/testing/selftests/vm/run_vmtests | 22 + 31 files changed, 1145 insertions(+), 369 deletions(-) create mode 100644 Documentation/core-api/pin_user_pages.rst --- 2.24.1