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From: John Hubbard <jhubbard@nvidia.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Al Viro" <viro@zeniv.linux.org.uk>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Dave Chinner" <david@fromorbit.com>,
	"David Airlie" <airlied@linux.ie>,
	"David S . Miller" <davem@davemloft.net>,
	"Ira Weiny" <ira.weiny@intel.com>, "Jan Kara" <jack@suse.cz>,
	"Jason Gunthorpe" <jgg@ziepe.ca>, "Jens Axboe" <axboe@kernel.dk>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Michal Hocko" <mhocko@suse.com>,
	"Mike Kravetz" <mike.kravetz@oracle.com>,
	"Paul Mackerras" <paulus@samba.org>,
	"Shuah Khan" <shuah@kernel.org>,
	"Vlastimil Babka" <vbabka@suse.cz>,
	bpf@vger.kernel.org, dri-devel@lists.freedesktop.org,
	kvm@vger.kernel.org, linux-block@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org,
	linux-rdma@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	netdev@vger.kernel.org, linux-mm@kvack.org,
	LKML <linux-kernel@vger.kernel.org>,
	"John Hubbard" <jhubbard@nvidia.com>
Subject: [PATCH v2 14/18] vfio, mm: pin_longterm_pages (FOLL_PIN) and put_user_page() conversion
Date: Sun, 3 Nov 2019 13:18:09 -0800	[thread overview]
Message-ID: <20191103211813.213227-15-jhubbard@nvidia.com> (raw)
In-Reply-To: <20191103211813.213227-1-jhubbard@nvidia.com>

1. Change vfio from get_user_pages(FOLL_LONGTERM), to
pin_longterm_pages(), which sets both FOLL_LONGTERM and FOLL_PIN.

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().

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

Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index d864277ea16f..795e13f3ef08 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -327,9 +327,8 @@ static int put_pfn(unsigned long pfn, int prot)
 {
 	if (!is_invalid_reserved_pfn(pfn)) {
 		struct page *page = 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;
@@ -349,11 +348,11 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
 
 	down_read(&mm->mmap_sem);
 	if (mm == current->mm) {
-		ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page,
-				     vmas);
+		ret = pin_longterm_pages(vaddr, 1, flags, page, vmas);
 	} else {
-		ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page,
-					    vmas, NULL);
+		ret = pin_longterm_pages_remote(NULL, mm, vaddr, 1,
+						flags, page, vmas,
+						NULL);
 		/*
 		 * The lifetime of a vaddr_get_pfn() page pin is
 		 * userspace-controlled. In the fs-dax case this could
@@ -363,7 +362,7 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
 		 */
 		if (ret > 0 && vma_is_fsdax(vmas[0])) {
 			ret = -EOPNOTSUPP;
-			put_page(page[0]);
+			put_user_page(page[0]);
 		}
 	}
 	up_read(&mm->mmap_sem);
-- 
2.23.0


  parent reply	other threads:[~2019-11-03 21:20 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-03 21:17 [PATCH v2 00/18] mm/gup: track dma-pinned pages: FOLL_PIN, FOLL_LONGTERM John Hubbard
2019-11-03 21:17 ` [PATCH v2 01/18] mm/gup: pass flags arg to __gup_device_* functions John Hubbard
2019-11-04 16:39   ` Jerome Glisse
2019-11-03 21:17 ` [PATCH v2 02/18] mm/gup: factor out duplicate code from four routines John Hubbard
2019-11-04 16:51   ` Jerome Glisse
2019-11-03 21:17 ` [PATCH v2 03/18] goldish_pipe: rename local pin_user_pages() routine John Hubbard
2019-11-04 16:52   ` Jerome Glisse
2019-11-03 21:17 ` [PATCH v2 04/18] media/v4l2-core: set pages dirty upon releasing DMA buffers John Hubbard
2019-11-10 10:10   ` Hans Verkuil
2019-11-11 21:46     ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 05/18] mm/gup: introduce pin_user_pages*() and FOLL_PIN John Hubbard
2019-11-04 17:33   ` Jerome Glisse
2019-11-04 19:04     ` John Hubbard
2019-11-04 19:18       ` Jerome Glisse
2019-11-04 19:30         ` John Hubbard
2019-11-04 19:52           ` Jerome Glisse
2019-11-04 20:09             ` John Hubbard
2019-11-04 20:31               ` Jason Gunthorpe
2019-11-04 20:40                 ` John Hubbard
2019-11-04 20:31               ` Jerome Glisse
2019-11-04 20:37                 ` Jason Gunthorpe
2019-11-04 20:57                   ` John Hubbard
2019-11-04 21:15                     ` Jason Gunthorpe
2019-11-04 21:34                       ` John Hubbard
2019-11-04 20:33   ` David Rientjes
2019-11-04 20:48     ` Jerome Glisse
2019-11-05 13:10   ` Mike Rapoport
2019-11-05 19:00     ` John Hubbard
2019-11-07  2:25       ` Ira Weiny
2019-11-07  8:07       ` Mike Rapoport
2019-11-03 21:18 ` [PATCH v2 06/18] goldish_pipe: convert to pin_user_pages() and put_user_page() John Hubbard
2019-11-03 21:18 ` [PATCH v2 07/18] infiniband: set FOLL_PIN, FOLL_LONGTERM via pin_longterm_pages*() John Hubbard
2019-11-04 20:33   ` Jason Gunthorpe
2019-11-04 20:48     ` John Hubbard
2019-11-04 20:57       ` Jason Gunthorpe
2019-11-04 22:03         ` John Hubbard
2019-11-05  2:32           ` Jason Gunthorpe
2019-11-07  2:26         ` Ira Weiny
2019-11-03 21:18 ` [PATCH v2 08/18] mm/process_vm_access: set FOLL_PIN via pin_user_pages_remote() John Hubbard
2019-11-04 17:41   ` Jerome Glisse
2019-11-03 21:18 ` [PATCH v2 09/18] drm/via: set FOLL_PIN via pin_user_pages_fast() John Hubbard
2019-11-04 17:44   ` Jerome Glisse
2019-11-04 18:22     ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 10/18] fs/io_uring: set FOLL_PIN via pin_user_pages() John Hubbard
2019-11-03 21:18 ` [PATCH v2 11/18] net/xdp: " John Hubbard
2019-11-03 21:18 ` [PATCH v2 12/18] mm/gup: track FOLL_PIN pages John Hubbard
2019-11-04 18:52   ` Jerome Glisse
2019-11-04 22:49     ` John Hubbard
2019-11-04 23:49       ` Jerome Glisse
2019-11-05  0:18         ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 13/18] media/v4l2-core: pin_longterm_pages (FOLL_PIN) and put_user_page() conversion John Hubbard
2019-11-10 10:11   ` Hans Verkuil
2019-11-03 21:18 ` John Hubbard [this message]
2019-11-03 21:18 ` [PATCH v2 15/18] powerpc: book3s64: convert to pin_longterm_pages() and put_user_page() John Hubbard
2019-11-03 21:18 ` [PATCH v2 16/18] mm/gup_benchmark: support pin_user_pages() and related calls John Hubbard
2019-11-03 21:18 ` [PATCH v2 17/18] selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage John Hubbard
2019-11-03 21:18 ` [PATCH v2 18/18] mm/gup: remove support for gup(FOLL_LONGTERM) John Hubbard

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