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    Subject[PATCH 3/4] mm: gup: use get_user_pages_fast and get_user_pages_unlocked
    Date
    Just an optimization.

    Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
    ---
    drivers/dma/iovlock.c | 10 ++--------
    drivers/iommu/amd_iommu_v2.c | 6 ++----
    drivers/media/pci/ivtv/ivtv-udma.c | 6 ++----
    drivers/misc/sgi-gru/grufault.c | 3 +--
    drivers/scsi/st.c | 10 ++--------
    drivers/video/fbdev/pvr2fb.c | 5 +----
    mm/mempolicy.c | 2 +-
    mm/process_vm_access.c | 7 ++-----
    mm/util.c | 10 ++--------
    net/ceph/pagevec.c | 9 ++++-----
    10 files changed, 19 insertions(+), 49 deletions(-)

    diff --git a/drivers/dma/iovlock.c b/drivers/dma/iovlock.c
    index bb48a57..12ea7c3 100644
    --- a/drivers/dma/iovlock.c
    +++ b/drivers/dma/iovlock.c
    @@ -95,17 +95,11 @@ struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len)
    pages += page_list->nr_pages;

    /* pin pages down */
    - down_read(&current->mm->mmap_sem);
    - ret = get_user_pages(
    - current,
    - current->mm,
    + ret = get_user_pages_fast(
    (unsigned long) iov[i].iov_base,
    page_list->nr_pages,
    1, /* write */
    - 0, /* force */
    - page_list->pages,
    - NULL);
    - up_read(&current->mm->mmap_sem);
    + page_list->pages);

    if (ret != page_list->nr_pages)
    goto unpin;
    diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
    index 5f578e8..6963b73 100644
    --- a/drivers/iommu/amd_iommu_v2.c
    +++ b/drivers/iommu/amd_iommu_v2.c
    @@ -519,10 +519,8 @@ static void do_fault(struct work_struct *work)

    write = !!(fault->flags & PPR_FAULT_WRITE);

    - down_read(&fault->state->mm->mmap_sem);
    - npages = get_user_pages(NULL, fault->state->mm,
    - fault->address, 1, write, 0, &page, NULL);
    - up_read(&fault->state->mm->mmap_sem);
    + npages = get_user_pages_unlocked(NULL, fault->state->mm,
    + fault->address, 1, write, 0, &page);

    if (npages == 1) {
    put_page(page);
    diff --git a/drivers/media/pci/ivtv/ivtv-udma.c b/drivers/media/pci/ivtv/ivtv-udma.c
    index 7338cb2..96d866b 100644
    --- a/drivers/media/pci/ivtv/ivtv-udma.c
    +++ b/drivers/media/pci/ivtv/ivtv-udma.c
    @@ -124,10 +124,8 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
    }

    /* Get user pages for DMA Xfer */
    - down_read(&current->mm->mmap_sem);
    - err = get_user_pages(current, current->mm,
    - user_dma.uaddr, user_dma.page_count, 0, 1, dma->map, NULL);
    - up_read(&current->mm->mmap_sem);
    + err = get_user_pages_unlocked(current, current->mm,
    + user_dma.uaddr, user_dma.page_count, 0, 1, dma->map);

    if (user_dma.page_count != err) {
    IVTV_DEBUG_WARN("failed to map user pages, returned %d instead of %d\n",
    diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
    index f74fc0c..cd20669 100644
    --- a/drivers/misc/sgi-gru/grufault.c
    +++ b/drivers/misc/sgi-gru/grufault.c
    @@ -198,8 +198,7 @@ static int non_atomic_pte_lookup(struct vm_area_struct *vma,
    #else
    *pageshift = PAGE_SHIFT;
    #endif
    - if (get_user_pages
    - (current, current->mm, vaddr, 1, write, 0, &page, NULL) <= 0)
    + if (get_user_pages_fast(vaddr, 1, write, &page) <= 0)
    return -EFAULT;
    *paddr = page_to_phys(page);
    put_page(page);
    diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
    index aff9689..c89dcfa 100644
    --- a/drivers/scsi/st.c
    +++ b/drivers/scsi/st.c
    @@ -4536,18 +4536,12 @@ static int sgl_map_user_pages(struct st_buffer *STbp,
    return -ENOMEM;

    /* Try to fault in all of the necessary pages */
    - down_read(&current->mm->mmap_sem);
    /* rw==READ means read from drive, write into memory area */
    - res = get_user_pages(
    - current,
    - current->mm,
    + res = get_user_pages_fast(
    uaddr,
    nr_pages,
    rw == READ,
    - 0, /* don't force */
    - pages,
    - NULL);
    - up_read(&current->mm->mmap_sem);
    + pages);

    /* Errors and no page mapped should return here */
    if (res < nr_pages)
    diff --git a/drivers/video/fbdev/pvr2fb.c b/drivers/video/fbdev/pvr2fb.c
    index 167cfff..ff81f65 100644
    --- a/drivers/video/fbdev/pvr2fb.c
    +++ b/drivers/video/fbdev/pvr2fb.c
    @@ -686,10 +686,7 @@ static ssize_t pvr2fb_write(struct fb_info *info, const char *buf,
    if (!pages)
    return -ENOMEM;

    - down_read(&current->mm->mmap_sem);
    - ret = get_user_pages(current, current->mm, (unsigned long)buf,
    - nr_pages, WRITE, 0, pages, NULL);
    - up_read(&current->mm->mmap_sem);
    + ret = get_user_pages_fast((unsigned long)buf, nr_pages, WRITE, pages);

    if (ret < nr_pages) {
    nr_pages = ret;
    diff --git a/mm/mempolicy.c b/mm/mempolicy.c
    index 8f5330d..6606c10 100644
    --- a/mm/mempolicy.c
    +++ b/mm/mempolicy.c
    @@ -881,7 +881,7 @@ static int lookup_node(struct mm_struct *mm, unsigned long addr)
    struct page *p;
    int err;

    - err = get_user_pages(current, mm, addr & PAGE_MASK, 1, 0, 0, &p, NULL);
    + err = get_user_pages_fast(addr & PAGE_MASK, 1, 0, &p);
    if (err >= 0) {
    err = page_to_nid(p);
    put_page(p);
    diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
    index 5077afc..b159769 100644
    --- a/mm/process_vm_access.c
    +++ b/mm/process_vm_access.c
    @@ -99,11 +99,8 @@ static int process_vm_rw_single_vec(unsigned long addr,
    size_t bytes;

    /* Get the pages we're interested in */
    - down_read(&mm->mmap_sem);
    - pages = get_user_pages(task, mm, pa, pages,
    - vm_write, 0, process_pages, NULL);
    - up_read(&mm->mmap_sem);
    -
    + pages = get_user_pages_unlocked(task, mm, pa, pages,
    + vm_write, 0, process_pages);
    if (pages <= 0)
    return -EFAULT;

    diff --git a/mm/util.c b/mm/util.c
    index 093c973..1b93f2d 100644
    --- a/mm/util.c
    +++ b/mm/util.c
    @@ -247,14 +247,8 @@ int __weak get_user_pages_fast(unsigned long start,
    int nr_pages, int write, struct page **pages)
    {
    struct mm_struct *mm = current->mm;
    - int ret;
    -
    - down_read(&mm->mmap_sem);
    - ret = get_user_pages(current, mm, start, nr_pages,
    - write, 0, pages, NULL);
    - up_read(&mm->mmap_sem);
    -
    - return ret;
    + return get_user_pages_unlocked(current, mm, start, nr_pages,
    + write, 0, pages);
    }
    EXPORT_SYMBOL_GPL(get_user_pages_fast);

    diff --git a/net/ceph/pagevec.c b/net/ceph/pagevec.c
    index 5550130..5504783 100644
    --- a/net/ceph/pagevec.c
    +++ b/net/ceph/pagevec.c
    @@ -23,17 +23,16 @@ struct page **ceph_get_direct_page_vector(const void __user *data,
    if (!pages)
    return ERR_PTR(-ENOMEM);

    - down_read(&current->mm->mmap_sem);
    while (got < num_pages) {
    - rc = get_user_pages(current, current->mm,
    - (unsigned long)data + ((unsigned long)got * PAGE_SIZE),
    - num_pages - got, write_page, 0, pages + got, NULL);
    + rc = get_user_pages_fast((unsigned long)data +
    + ((unsigned long)got * PAGE_SIZE),
    + num_pages - got,
    + write_page, pages + got);
    if (rc < 0)
    break;
    BUG_ON(rc == 0);
    got += rc;
    }
    - up_read(&current->mm->mmap_sem);
    if (rc < 0)
    goto fail;
    return pages;

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