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    Subject[PATCH 13/28] mm/gup: Expose mm_populate_vma() for use when the vma is known
    Date
    When a vma is known, avoid calling mm_populate to search for the vma to
    populate.

    Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
    ---
    include/linux/mm.h | 4 ++++
    mm/gup.c | 20 ++++++++++++++++++++
    2 files changed, 24 insertions(+)

    diff --git a/include/linux/mm.h b/include/linux/mm.h
    index 1bfa2ee41187d..6cc8825f26414 100644
    --- a/include/linux/mm.h
    +++ b/include/linux/mm.h
    @@ -2587,8 +2587,12 @@ static inline void mm_populate(unsigned long addr, unsigned long len)
    /* Ignore errors */
    (void) __mm_populate(addr, len, 1);
    }
    +extern void mm_populate_vma(struct vm_area_struct *vma, unsigned long start,
    + unsigned long end);
    #else
    static inline void mm_populate(unsigned long addr, unsigned long len) {}
    +void mm_populate_vma(struct vm_area_struct *vma, unsigned long start,
    + unsigned long end) {}
    #endif

    /* These take the mm semaphore themselves */
    diff --git a/mm/gup.c b/mm/gup.c
    index 102877ed77a4b..522f8fd491ead 100644
    --- a/mm/gup.c
    +++ b/mm/gup.c
    @@ -1431,6 +1431,26 @@ long populate_vma_page_range(struct vm_area_struct *vma,
    NULL, NULL, locked);
    }

    +/*
    + * mm_populate_vma() - Populate a single range in a single vma.
    + * @vma: The vma to populate.
    + * @start: The start address to populate
    + * @end: The end address to stop populating
    + *
    + * Note: Ignores errors.
    + */
    +void mm_populate_vma(struct vm_area_struct *vma, unsigned long start,
    + unsigned long end)
    +{
    + struct mm_struct *mm = current->mm;
    + int locked = 1;
    +
    + mmap_read_lock(mm);
    + populate_vma_page_range(vma, start, end, &locked);
    + if (locked)
    + mmap_read_unlock(mm);
    +}
    +
    /*
    * __mm_populate - populate and/or mlock pages within a range of address space.
    *
    --
    2.28.0
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