From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: DRI Development <dri-devel@lists.freedesktop.org>,
LKML <linux-kernel@vger.kernel.org>
Cc: kvm@vger.kernel.org, linux-mm@kvack.org,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org,
linux-s390@vger.kernel.org,
"Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Daniel Vetter" <daniel.vetter@intel.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Pawel Osciak" <pawel@osciak.com>,
"Marek Szyprowski" <m.szyprowski@samsung.com>,
"Kyungmin Park" <kyungmin.park@samsung.com>,
"Tomasz Figa" <tfiga@chromium.org>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"John Hubbard" <jhubbard@nvidia.com>,
"Jérôme Glisse" <jglisse@redhat.com>, "Jan Kara" <jack@suse.cz>,
"Dan Williams" <dan.j.williams@intel.com>
Subject: [PATCH v4 05/15] mm/frame-vector: Use FOLL_LONGTERM
Date: Mon, 26 Oct 2020 11:58:08 +0100 [thread overview]
Message-ID: <20201026105818.2585306-6-daniel.vetter@ffwll.ch> (raw)
In-Reply-To: <20201026105818.2585306-1-daniel.vetter@ffwll.ch>
This is used by media/videbuf2 for persistent dma mappings, not just
for a single dma operation and then freed again, so needs
FOLL_LONGTERM.
Unfortunately current pup_locked doesn't support FOLL_LONGTERM due to
locking issues. Rework the code to pull the pup path out from the
mmap_sem critical section as suggested by Jason.
By relying entirely on the vma checks in pin_user_pages and follow_pfn
(for vm_flags and vma_is_fsdax) we can also streamline the code a lot.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Pawel Osciak <pawel@osciak.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
--
v2: Streamline the code and further simplify the loop checks (Jason)
---
mm/frame_vector.c | 50 ++++++++++++++---------------------------------
1 file changed, 15 insertions(+), 35 deletions(-)
diff --git a/mm/frame_vector.c b/mm/frame_vector.c
index 10f82d5643b6..d44779e56313 100644
--- a/mm/frame_vector.c
+++ b/mm/frame_vector.c
@@ -38,7 +38,6 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
struct vm_area_struct *vma;
int ret = 0;
int err;
- int locked;
if (nr_frames == 0)
return 0;
@@ -48,40 +47,25 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
start = untagged_addr(start);
- mmap_read_lock(mm);
- locked = 1;
- vma = find_vma_intersection(mm, start, start + 1);
- if (!vma) {
- ret = -EFAULT;
- goto out;
- }
-
- /*
- * While get_vaddr_frames() could be used for transient (kernel
- * controlled lifetime) pinning of memory pages all current
- * users establish long term (userspace controlled lifetime)
- * page pinning. Treat get_vaddr_frames() like
- * get_user_pages_longterm() and disallow it for filesystem-dax
- * mappings.
- */
- if (vma_is_fsdax(vma)) {
- ret = -EOPNOTSUPP;
- goto out;
- }
-
- if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
+ ret = pin_user_pages_fast(start, nr_frames,
+ FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM,
+ (struct page **)(vec->ptrs));
+ if (ret > 0) {
vec->got_ref = true;
vec->is_pfns = false;
- ret = pin_user_pages_locked(start, nr_frames,
- gup_flags, (struct page **)(vec->ptrs), &locked);
- goto out;
+ goto out_unlocked;
}
+ mmap_read_lock(mm);
vec->got_ref = false;
vec->is_pfns = true;
do {
unsigned long *nums = frame_vector_pfns(vec);
+ vma = find_vma_intersection(mm, start, start + 1);
+ if (!vma)
+ break;
+
while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
err = follow_pfn(vma, start, &nums[ret]);
if (err) {
@@ -92,17 +76,13 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
start += PAGE_SIZE;
ret++;
}
- /*
- * We stop if we have enough pages or if VMA doesn't completely
- * cover the tail page.
- */
- if (ret >= nr_frames || start < vma->vm_end)
+ /* Bail out if VMA doesn't completely cover the tail page. */
+ if (start < vma->vm_end)
break;
- vma = find_vma_intersection(mm, start, start + 1);
- } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP));
+ } while (ret < nr_frames);
out:
- if (locked)
- mmap_read_unlock(mm);
+ mmap_read_unlock(mm);
+out_unlocked:
if (!ret)
ret = -EFAULT;
if (ret > 0)
--
2.28.0
next prev parent reply other threads:[~2020-10-26 11:00 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 10:58 [PATCH v4 00/15] follow_pfn and other iomap races Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 01/15] drm/exynos: Stop using frame_vector helpers Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 02/15] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 03/15] misc/habana: Stop using frame_vector helpers Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 04/15] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter
2020-10-26 10:58 ` Daniel Vetter [this message]
2020-10-26 22:15 ` [PATCH v4 05/15] mm/frame-vector: Use FOLL_LONGTERM Tomasz Figa
2020-10-27 8:05 ` Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 06/15] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter
2020-10-26 22:03 ` Tomasz Figa
2020-10-26 10:58 ` [PATCH v4 07/15] mm: Close race in generic_access_phys Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 08/15] mm: Add unsafe_follow_pfn Daniel Vetter
2020-10-29 8:56 ` Christoph Hellwig
2020-10-29 9:23 ` Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 09/15] media/videbuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter
2020-10-26 22:02 ` Tomasz Figa
2020-10-26 10:58 ` [PATCH v4 10/15] vfio/type1: Mark follow_pfn " Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 11/15] PCI: Obey iomem restrictions for procfs mmap Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 12/15] /dev/mem: Only set filp->f_mapping Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 13/15] resource: Move devmem revoke code to resource framework Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 14/15] sysfs: Support zapping of binary attr mmaps Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 15/15] PCI: Revoke mappings like devmem Daniel Vetter
2020-10-29 8:57 ` [PATCH v4 00/15] follow_pfn and other iomap races Christoph Hellwig
2020-10-29 9:25 ` Daniel Vetter
2020-10-29 9:28 ` Christoph Hellwig
2020-10-29 9:38 ` Daniel Vetter
2020-10-29 10:01 ` Christoph Hellwig
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