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author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2020-11-27 17:41:19 +0100 |
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committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2021-01-12 14:15:17 +0100 |
commit | 04769cb1c45a919cd94b931e6494d2a9afc32914 (patch) | |
tree | 6866e55a7a05329ede8acf045c3fdcf6897a276a /mm/frame_vector.c | |
parent | d88a0c169bd535182547c54933a38b2afd553f44 (diff) | |
download | linux-04769cb1c45a919cd94b931e6494d2a9afc32914.tar.gz linux-04769cb1c45a919cd94b931e6494d2a9afc32914.tar.bz2 linux-04769cb1c45a919cd94b931e6494d2a9afc32914.zip |
mm/frame-vector: Use FOLL_LONGTERM
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.
Note that pin_user_pages_fast is a safe replacement despite the
seeming lack of checking for vma->vm_flasg & (VM_IO | VM_PFNMAP). Such
ptes are marked with pte_mkspecial (which pup_fast rejects in the
fastpath), and only architectures supporting that support the
pin_user_pages_fast fastpath.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
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>
Link: https://patchwork.freedesktop.org/patch/msgid/20201127164131.2244124-6-daniel.vetter@ffwll.ch
Diffstat (limited to 'mm/frame_vector.c')
-rw-r--r-- | mm/frame_vector.c | 53 |
1 files changed, 17 insertions, 36 deletions
diff --git a/mm/frame_vector.c b/mm/frame_vector.c index 10f82d5643b6..f8c34b895c76 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -32,13 +32,12 @@ * This function takes care of grabbing mmap_lock as necessary. */ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, - unsigned int gup_flags, struct frame_vector *vec) + struct frame_vector *vec) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; int ret = 0; int err; - int locked; if (nr_frames == 0) return 0; @@ -48,40 +47,26 @@ 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; + ret = 0; 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 +77,13 @@ 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) |