From patchwork Sun Nov 3 21:17:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11224559 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 ED8CE1599 for ; Sun, 3 Nov 2019 21:19:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C31E021D56 for ; Sun, 3 Nov 2019 21:19:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="QFdybeXk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728510AbfKCVSw (ORCPT ); Sun, 3 Nov 2019 16:18:52 -0500 Received: from hqemgate15.nvidia.com ([216.228.121.64]:17587 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728564AbfKCVS0 (ORCPT ); Sun, 3 Nov 2019 16:18:26 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate15.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Sun, 03 Nov 2019 13:18:20 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Sun, 03 Nov 2019 13:18:15 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Sun, 03 Nov 2019 13:18:15 -0800 Received: from HQMAIL107.nvidia.com (172.20.187.13) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Sun, 3 Nov 2019 21:18:14 +0000 Received: from hqnvemgw01.nvidia.com (172.20.150.20) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Sun, 3 Nov 2019 21:18:14 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by hqnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Sun, 03 Nov 2019 13:18:14 -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 v2 00/18] mm/gup: track dma-pinned pages: FOLL_PIN, FOLL_LONGTERM Date: Sun, 3 Nov 2019 13:17:55 -0800 Message-ID: <20191103211813.213227-1-jhubbard@nvidia.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1572815900; bh=GBV3ojpDDK4OBFB22u5Rnbzd8rZTGnaPAeFzYUht8Sk=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: MIME-Version:X-NVConfidentiality:Content-Type: Content-Transfer-Encoding; b=QFdybeXkgDaSikqJK8ut4Q3VaoLQPZvaXrOil25JjZA2drY+qH3mlg/JBBJj9CUkO FnWKh3HSWK12fVcCDfgZO3gj/PnKbOvnlx3cF6Te3oPgt64K0ScQSZlilcWgNVErRp sBQIZRfXIN70b0dwEGF4SAgE3WxBXUjfhgUu/ST459bfzdU7/J3Tc57sm0hCck2WzM Bl+CFxB3+DoOCzmMTNIsqpCr4cDD8LlzCDt9L0jqubkzo4mR4fOaGh5xqUeGuMOfU2 OjOwLPsBvhDoaFgYYO+pfhwHgHAniOj+t7ll1ShzRTew8tOKK1v2qpbIc7QX9UbfSG iajQXzs4Buv0A== Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi, Changes since v1: * Changed the function signature of __huge_pt_done() from int to void. * Renamed __remove_refs_from_head() to put_compound_head(). * Improved the comment documentation in mm.h and gup.c * Merged Documentation/vm/pin_user_pages.rst into the "introduce FOLL_PIN" patch. * Fixed Documentation/vm/pin_user_pages.rst: * Fixed up a TODO about DAX. * 31, not 32 bits total are available for counting * Deleted some stale comments from the commit description of the VFIO patch. * Added Reviewed-by tags from Ira Weiny and Jens Axboe, and Acked-by from Björn Töpel. ====================================================================== Original cover letter (edited to fix up the patch description numbers) 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 ============================================================ 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 (18): 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/index.rst | 1 + Documentation/vm/pin_user_pages.rst | 212 +++++++ 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 | 142 ++++- include/linux/mmzone.h | 2 + include/linux/page_ref.h | 10 + mm/gup.c | 594 ++++++++++++++++---- 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, 1054 insertions(+), 264 deletions(-) create mode 100644 Documentation/vm/pin_user_pages.rst