From patchwork Thu Jun 13 21:42:02 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kasireddy, Vivek" X-Patchwork-Id: 13697529 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BBFCCC27C4F for ; Thu, 13 Jun 2024 22:13:39 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E4EA010EBC5; Thu, 13 Jun 2024 22:13:38 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="acln2FQr"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7E0FC10EBC1 for ; Thu, 13 Jun 2024 22:13:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1718316817; x=1749852817; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=yuUIuebr9y7FqrecXTQRweoo9mv++jkQ761EA3G8Lv4=; b=acln2FQrp/+XBQLj09jGW8uerp9hvhY2Pu/41G3U1xVsZGVZuopTNe29 rnWXIiiaYxqoLsNpMdHY7YRh4cVKLkNL6AtYDhs6Zo9wJTMsQiXTNki8S Jiqj6oKBN6G3r5NqGkYZ4WXEA7pLv3gjSzlhK6YEtkkmsXfkJ6mGC5AXS zXKIw7WAOMXDeb4SV2ny47+CHCVlKY1y60GrSmZFHc9rgaF5maUes3cV0 qA73IxGM3/2EPEXkpXMGEYpxxEKD/3os8C2pvzakycUeC6V5VB4ZUooA+ mVazNMxM8VLvwcz57AHeWgwNo0WmWejpE9H6rMmPHnuauDYgtXE/eJnon A==; X-CSE-ConnectionGUID: GSdCYk0nQ9Kz0LrzDMUEuQ== X-CSE-MsgGUID: +vhkGIqcRUK/YP6xugQbHw== X-IronPort-AV: E=McAfee;i="6700,10204,11102"; a="32720524" X-IronPort-AV: E=Sophos;i="6.08,236,1712646000"; d="scan'208";a="32720524" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jun 2024 15:13:35 -0700 X-CSE-ConnectionGUID: OKRhEZ8YQw2JKdggKpIabQ== X-CSE-MsgGUID: bdPVqlA0STSBFwkSzUkJ3Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,236,1712646000"; d="scan'208";a="45214087" Received: from vkasired-desk2.fm.intel.com ([10.105.128.132]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jun 2024 15:13:35 -0700 From: Vivek Kasireddy To: dri-devel@lists.freedesktop.org, linux-mm@kvack.org Cc: Vivek Kasireddy , David Hildenbrand , Matthew Wilcox , Christoph Hellwig , Andrew Morton , Daniel Vetter , Hugh Dickins , Peter Xu , Jason Gunthorpe , Gerd Hoffmann , Dongwon Kim , Junxiao Chang Subject: [PATCH v15 0/9] mm/gup: Introduce memfd_pin_folios() for pinning memfd folios Date: Thu, 13 Jun 2024 14:42:02 -0700 Message-ID: <20240613214741.1029446-1-vivek.kasireddy@intel.com> X-Mailer: git-send-email 2.45.1 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Currently, some drivers (e.g, Udmabuf) that want to longterm-pin the pages/folios associated with a memfd, do so by simply taking a reference on them. This is not desirable because the pages/folios may reside in Movable zone or CMA block. Therefore, having drivers use memfd_pin_folios() API ensures that the folios are appropriately pinned via FOLL_PIN for longterm DMA. This patchset also introduces a few helpers and converts the Udmabuf driver to use folios and memfd_pin_folios() API to longterm-pin the folios for DMA. Two new Udmabuf selftests are also included to test the driver and the new API. --- Patchset overview: Patch 1-2: GUP helpers to migrate and unpin one or more folios Patch 3: Introduce memfd_pin_folios() API Patch 4-5: Udmabuf driver bug fixes for Qemu + hugetlb=on, blob=true case Patch 6-8: Convert Udmabuf to use memfd_pin_folios() and add selftests This series is tested using the following methods: - Run the subtests added in Patch 8 - Run Qemu (master) with the following options and a few additional patches to Spice: qemu-system-x86_64 -m 4096m.... -device virtio-gpu-pci,max_outputs=1,blob=true,xres=1920,yres=1080 -spice port=3001,gl=on,disable-ticketing=on,preferred-codec=gstreamer:h264 -object memory-backend-memfd,hugetlb=on,id=mem1,size=4096M -machine memory-backend=mem1 - Run source ./run_vmtests.sh -t gup_test -a to check GUP regressions Changelog: v14 -> v15: - Add an error check start < 0 in memfd_pin_folios() - Return an error in udmabuf driver if memfd_pin_folios() returns 0 These two checks fix the following issue identified by syzbot: https://syzkaller.appspot.com/bug?extid=40c7dad27267f61839d4 - Set memfd = NULL before dmabuf export to ensure that memfd is not closed twice on error. This fixes the following syzbot issue: https://syzkaller.appspot.com/bug?extid=b2cfdac9ae5278d4b621 v13 -> v14: - Drop the redundant comments before check_and_migrate_movable_pages() and refer to check_and_migrate_movable_folios() comments (David) - Use appropriate ksft_* functions for printing and KSFT_* codes for exit() in udmabuf selftest (Shuah) - Add Mike Kravetz's suggested-by tag in udmabuf selftest patch (Shuah) - Collect Ack and Rb tags from David v12 -> v13: (suggestions from David) - Drop the sanity checks in unpin_folio()/unpin_folios() due to unavailability of per folio anon-exclusive flag - Export unpin_folio()/unpin_folios() using EXPORT_SYMBOL_GPL instead of EXPORT_SYMBOL - Have check_and_migrate_movable_pages() just call check_and_migrate_movable_folios() instead of calling other helpers - Slightly improve the comments and commit messages v11 -> v12: - Rebased and tested on mm-unstable v10 -> v11: - Remove the version string from the patch subject (Andrew) - Move the changelog from the patches into the cover letter - Rearrange the patchset to have GUP patches at the beginning v9 -> v10: - Introduce and use unpin_folio(), unpin_folios() and check_and_migrate_movable_folios() helpers - Use a list to track the folios that need to be unpinned in udmabuf v8 -> v9: (suggestions from Matthew) - Drop the extern while declaring memfd_alloc_folio() - Fix memfd_alloc_folio() declaration to have it return struct folio * instead of struct page * when CONFIG_MEMFD_CREATE is not defined - Use folio_pfn() on the folio instead of page_to_pfn() on head page in udmabuf - Don't split the arguments to shmem_read_folio() on multiple lines in udmabuf v7 -> v8: (suggestions from David) - Have caller pass [start, end], max_folios instead of start, nr_pages - Replace offsets array with just offset into the first page - Add comments explaning the need for next_idx - Pin (and return) the folio (via FOLL_PIN) only once v6 -> v7: - Rename this API to memfd_pin_folios() and make it return folios and offsets instead of pages (David) - Don't continue processing the folios in the batch returned by filemap_get_folios_contig() if they do not have correct next_idx - Add the R-b tag from Christoph v5 -> v6: (suggestions from Christoph) - Rename this API to memfd_pin_user_pages() to make it clear that it is intended for memfds - Move the memfd page allocation helper from gup.c to memfd.c - Fix indentation errors in memfd_pin_user_pages() - For contiguous ranges of folios, use a helper such as filemap_get_folios_contig() to lookup the page cache in batches - Split the processing of hugetlb or shmem pages into helpers to simplify the code in udmabuf_create() v4 -> v5: (suggestions from David) - For hugetlb case, ensure that we only obtain head pages from the mapping by using __filemap_get_folio() instead of find_get_page_flags() - Handle -EEXIST when two or more potential users try to simultaneously add a huge page to the mapping by forcing them to retry on failure v3 -> v4: - Remove the local variable "page" and instead use 3 return statements in alloc_file_page() (David) - Add the R-b tag from David v2 -> v3: (suggestions from David) - Enclose the huge page allocation code with #ifdef CONFIG_HUGETLB_PAGE (Build error reported by kernel test robot ) - Don't forget memalloc_pin_restore() on non-migration related errors - Improve the readability of the cleanup code associated with non-migration related errors - Augment the comments by describing FOLL_LONGTERM like behavior - Include the R-b tag from Jason v1 -> v2: - Drop gup_flags and improve comments and commit message (David) - Allocate a page if we cannot find in page cache for the hugetlbfs case as well (David) - Don't unpin pages if there is a migration related failure (David) - Drop the unnecessary nr_pages <= 0 check (Jason) - Have the caller of the API pass in file * instead of fd (Jason) Cc: David Hildenbrand Cc: Matthew Wilcox (Oracle) Cc: Christoph Hellwig Cc: Andrew Morton Cc: Daniel Vetter Cc: Hugh Dickins Cc: Peter Xu Cc: Jason Gunthorpe Cc: Gerd Hoffmann Cc: Dongwon Kim Cc: Junxiao Chang Arnd Bergmann (1): udmabuf: add CONFIG_MMU dependency Vivek Kasireddy (8): mm/gup: Introduce unpin_folio/unpin_folios helpers mm/gup: Introduce check_and_migrate_movable_folios() mm/gup: Introduce memfd_pin_folios() for pinning memfd folios udmabuf: Use vmf_insert_pfn and VM_PFNMAP for handling mmap udmabuf: Add back support for mapping hugetlb pages udmabuf: Convert udmabuf driver to use folios udmabuf: Pin the pages using memfd_pin_folios() API selftests/udmabuf: Add tests to verify data after page migration drivers/dma-buf/Kconfig | 1 + drivers/dma-buf/udmabuf.c | 232 +++++++++---- include/linux/memfd.h | 5 + include/linux/mm.h | 5 + mm/gup.c | 307 +++++++++++++++--- mm/memfd.c | 35 ++ .../selftests/drivers/dma-buf/udmabuf.c | 214 ++++++++++-- 7 files changed, 662 insertions(+), 137 deletions(-)