From patchwork Tue Jan 7 22:45:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11322273 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 74DB1930 for ; Tue, 7 Jan 2020 22:49:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 42F7A2077B for ; Tue, 7 Jan 2020 22:49:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="q07jqBkO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728357AbgAGWsv (ORCPT ); Tue, 7 Jan 2020 17:48:51 -0500 Received: from hqnvemgate25.nvidia.com ([216.228.121.64]:5120 "EHLO hqnvemgate25.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727174AbgAGWqF (ORCPT ); Tue, 7 Jan 2020 17:46:05 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 07 Jan 2020 14:45:42 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Tue, 07 Jan 2020 14:46:00 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 07 Jan 2020 14:46:00 -0800 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 7 Jan 2020 22:45:59 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Tue, 7 Jan 2020 22:45:59 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Tue, 07 Jan 2020 14:45:59 -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?= , "Kirill A . Shutemov" , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML , John Hubbard Subject: [PATCH v12 00/22] mm/gup: prereqs to track dma-pinned pages: FOLL_PIN Date: Tue, 7 Jan 2020 14:45:36 -0800 Message-ID: <20200107224558.2362728-1-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=1578437143; bh=e35VbuH+5Gvq6hzdX1wkd7Gwo0Ev1/RydrM5ojZBtqQ=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: MIME-Version:X-NVConfidentiality:Content-Type: Content-Transfer-Encoding; b=q07jqBkOQ+8W+FWIGxHzDq9+K2aqK0l1baYh9tHJ5YgbVqzpzGrCVUbh8IIOz9ivr N8DeNKRxsksmaQmBj8DLUTfJNvVvliRP3A7UvdrQSBrUtqohAPvBbP6gW+d+uir7zj N71u+jUUFG3a29ne3zY3zxuWMeCOBJOlbx0/C+htFPSQNDX+WeFBXBUo/FQBTcKPK+ fsKaVOXRA1UshywnsPhWCDuIhCymH6YPuMQwJ7/7x7UJimvasG4+G3pmoTyD3poYdy 39n4NbY3ownCfiBLFE6x3ANsClgsjxgyIpUe1k8mz3p84SQo7eboSdCD6jky2z1c7L WmXHM0fQFkghw== Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi, The "track FOLL_PIN pages" would have been the very next patch, but it is not included here because I'm still debugging a bug report from Leon. Let's get all of the prerequisite work (it's been reviewed) into the tree so that future reviews are easier. It's clear that any fixes that are required to the tracking patch, won't affect these patches here. This implements an API naming change (put_user_page*() --> unpin_user_page*()), and also adds FOLL_PIN page support, up to *but not including* actually tracking FOLL_PIN pages. It extends the FOLL_PIN support 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 v11: Fixes resulting from Kirill Shutemov's review, plus a fix for a kbuild robot-reported warning. * Only include the first 22 patches: up to, but not including, the "track FOLL_PIN pages" patch. * Improved the efficiency of put_compound_head(), by avoiding get_page() entirely, and instead doing the mass subtraction on one less than refs, followed by a final put_page(). * Got rid of the forward declaration of __gup_longterm_locked(), by moving get_user_pages_remote() further down in gup.c * Got rid of a redundant page_is_devmap_managed() call, and simplified put_devmap_managed_page() as part of that small cleanup. * Changed put_devmap_managed_page() to do an early out if the page is not devmap managed. This saves an indentation level. * Applied the same type of change to __unpin_devmap_managed_user_page(), which has the same checks. * Changed release_pages() to handle the changed put_devmap_managed_page() API. * Removed EXPORT_SYMBOL(free_devmap_managed_page), as it is not required, after the other refactoring. * Fixed a kbuild robot sparse warning: added "static" to try_pin_compound_head()'s declaration. 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 v11, which is here: https://lore.kernel.org/r/20191216222537.491123-1-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 rdma-core tests: rdma-core/build/bin/run_tests.py * 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 (21): 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 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() 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: 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 | 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 | 95 +++- mm/gup.c | 495 ++++++++++++-------- mm/gup_benchmark.c | 9 +- mm/memremap.c | 75 ++- mm/process_vm_access.c | 28 +- mm/swap.c | 27 +- net/xdp/xdp_umem.c | 4 +- tools/testing/selftests/vm/gup_benchmark.c | 6 +- 25 files changed, 762 insertions(+), 380 deletions(-) create mode 100644 Documentation/core-api/pin_user_pages.rst