Messages in this thread Patch in this message | | | From | John Hubbard <> | Subject | [PATCH v2 2/2] mm/gup: frame_vector: convert get_user_pages() --> pin_user_pages() | Date | Sun, 31 May 2020 16:41:31 -0700 |
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This code was using get_user_pages*(), and all of the callers so far were in a "Case 2" scenario (DMA/RDMA), using the categorization from [1]. That means that it's time to convert the get_user_pages*() + put_page() calls to pin_user_pages*() + unpin_user_pages() calls.
There is some helpful background in [2]: basically, this is a small part of fixing a long-standing disconnect between pinning pages, and file systems' use of those pages.
[1] Documentation/core-api/pin_user_pages.rst
[2] "Explicit pinning of user-space pages": https://lwn.net/Articles/807108/
Cc: David Hildenbrand <david@redhat.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> --- mm/frame_vector.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/mm/frame_vector.c b/mm/frame_vector.c index c431ca81dad5..4107dbca0056 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -72,7 +72,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { vec->got_ref = true; vec->is_pfns = false; - ret = get_user_pages_locked(start, nr_frames, + ret = pin_user_pages_locked(start, nr_frames, gup_flags, (struct page **)(vec->ptrs), &locked); goto out; } @@ -122,7 +122,6 @@ EXPORT_SYMBOL(get_vaddr_frames); */ void put_vaddr_frames(struct frame_vector *vec) { - int i; struct page **pages; if (!vec->got_ref) @@ -135,8 +134,8 @@ void put_vaddr_frames(struct frame_vector *vec) */ if (WARN_ON(IS_ERR(pages))) goto out; - for (i = 0; i < vec->nr_frames; i++) - put_page(pages[i]); + + unpin_user_pages(pages, vec->nr_frames); vec->got_ref = false; out: vec->nr_frames = 0; -- 2.26.2
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