From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 042/118] vfio, mm: pin_user_pages (FOLL_PIN) and put_user_page() conversion Date: Thu, 30 Jan 2020 22:13:24 -0800 Message-ID: <20200131061324.AO72PHl35%akpm@linux-foundation.org> References: <20200130221021.5f0211c56346d5485af07923@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Return-path: Received: from mail.kernel.org ([198.145.29.99]:32850 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725907AbgAaGN0 (ORCPT ); Fri, 31 Jan 2020 01:13:26 -0500 In-Reply-To: <20200130221021.5f0211c56346d5485af07923@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, alex.williamson@redhat.com, aneesh.kumar@linux.ibm.com, axboe@kernel.dk, bjorn.topel@intel.com, corbet@lwn.net, dan.j.williams@intel.com, daniel.vetter@ffwll.ch, hch@lst.de, hverkuil-cisco@xs4all.nl, ira.weiny@intel.com, jack@suse.cz, jgg@mellanox.com, jgg@ziepe.ca, jglisse@redhat.com, jhubbard@nvidia.com, kirill@shutemov.name, leonro@mellanox.com, linux-mm@kvack.org, mchehab@kernel.org, mm-commits@vger.kernel.org, rppt@linux.ibm.com, torvalds@linux-foundation.org =46rom: John Hubbard Subject: vfio, mm: pin_user_pages (FOLL_PIN) and put_user_page() conversion 1. Change vfio from get_user_pages_remote(), to pin_user_pages_remote(). 2. Because all FOLL_PIN-acquired pages must be released via put_user_page(), also convert the put_page() call over to put_user_pages_dirty_lock(). Note that this effectively changes the code's behavior in vfio_iommu_type1.c: put_pfn(): it now ultimately calls set_page_dirty_lock(), instead of set_page_dirty(). This is probably more accurate. As Christoph Hellwig put it, "set_page_dirty() is only safe if we are dealing with a file backed page where we have reference on the inode it hangs off." [1] [1] https://lore.kernel.org/r/20190723153640.GB720@lst.de Link: http://lkml.kernel.org/r/20200107224558.2362728-20-jhubbard@nvidia.com Signed-off-by: John Hubbard Tested-by: Alex Williamson Acked-by: Alex Williamson Cc: Aneesh Kumar K.V Cc: Bj=C3=B6rn T=C3=B6pel Cc: Christoph Hellwig Cc: Daniel Vetter Cc: Dan Williams Cc: Hans Verkuil Cc: Ira Weiny Cc: Jan Kara Cc: Jason Gunthorpe Cc: Jason Gunthorpe Cc: Jens Axboe Cc: Jerome Glisse Cc: Jonathan Corbet Cc: Kirill A. Shutemov Cc: Leon Romanovsky Cc: Mauro Carvalho Chehab Cc: Mike Rapoport Signed-off-by: Andrew Morton --- drivers/vfio/vfio_iommu_type1.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/drivers/vfio/vfio_iommu_type1.c~vfio-mm-pin_user_pages-foll_pin-and-p= ut_user_page-conversion +++ a/drivers/vfio/vfio_iommu_type1.c @@ -309,9 +309,8 @@ static int put_pfn(unsigned long pfn, in { if (!is_invalid_reserved_pfn(pfn)) { struct page *page =3D pfn_to_page(pfn); - if (prot & IOMMU_WRITE) - SetPageDirty(page); - put_page(page); + + put_user_pages_dirty_lock(&page, 1, prot & IOMMU_WRITE); return 1; } return 0; @@ -329,7 +328,7 @@ static int vaddr_get_pfn(struct mm_struc flags |=3D FOLL_WRITE; =20 down_read(&mm->mmap_sem); - ret =3D get_user_pages_remote(NULL, mm, vaddr, 1, flags | FOLL_LONGTERM, + ret =3D pin_user_pages_remote(NULL, mm, vaddr, 1, flags | FOLL_LONGTERM, page, NULL, NULL); if (ret =3D=3D 1) { *pfn =3D page_to_pfn(page[0]); _