[Qemu-devel] [PATCH 05/17] mm: gup: use get_user_pages_fast and get_user_pages_unlocked

[Andrea Arcangeli]

Just an optimization.

Signed-off-by: Andrea Arcangeli <address@hidden>
---
 drivers/dma/iovlock.c              | 10 ++--------
 drivers/iommu/amd_iommu_v2.c       |  6 ++----
 drivers/media/pci/ivtv/ivtv-udma.c |  6 ++----
 drivers/scsi/st.c                  | 10 ++--------
 drivers/video/fbdev/pvr2fb.c       |  5 +----
 mm/process_vm_access.c             |  7 ++-----
 mm/util.c                          | 10 ++--------
 net/ceph/pagevec.c                 |  9 ++++-----
 8 files changed, 17 insertions(+), 46 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/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/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;