1 files changed, 72 insertions, 31 deletions

diff --git a/mm/fremap.c b/mm/fremap.c
index 4e3f53dd5fd4..01e51f01b84e 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -126,6 +126,25 @@ out:
         return err;
 }
 
+static int populate_range(struct mm_struct *mm, struct vm_area_struct *vma,
+                        unsigned long addr, unsigned long size, pgoff_t pgoff)
+{
+        int err;
+
+        do {
+                err = install_file_pte(mm, vma, addr, pgoff, vma->vm_page_prot);
+                if (err)
+                        return err;
+
+                size -= PAGE_SIZE;
+                addr += PAGE_SIZE;
+                pgoff++;
+        } while (size);
+
+        return 0;
+
+}
+
 /***
  * sys_remap_file_pages - remap arbitrary pages of a shared backing store
  *                        file within an existing vma.
@@ -183,41 +202,63 @@ asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
          * the single existing vma.  vm_private_data is used as a
          * swapout cursor in a VM_NONLINEAR vma.
          */
-        if (vma && (vma->vm_flags & VM_SHARED) &&
-                (!vma->vm_private_data || (vma->vm_flags & VM_NONLINEAR)) &&
-                vma->vm_ops && vma->vm_ops->populate &&
-                        end > start && start >= vma->vm_start &&
-                                end <= vma->vm_end) {
-
-                /* Must set VM_NONLINEAR before any pages are populated. */
-                if (pgoff != linear_page_index(vma, start) &&
-                    !(vma->vm_flags & VM_NONLINEAR)) {
-                        if (!has_write_lock) {
-                                up_read(&mm->mmap_sem);
-                                down_write(&mm->mmap_sem);
-                                has_write_lock = 1;
-                                goto retry;
+        if (!vma || !(vma->vm_flags & VM_SHARED))
+                goto out;
+
+        if (vma->vm_private_data && !(vma->vm_flags & VM_NONLINEAR))
+                goto out;
+
+        if ((!vma->vm_ops || !vma->vm_ops->populate) &&
+                                        !(vma->vm_flags & VM_CAN_NONLINEAR))
+                goto out;
+
+        if (end <= start || start < vma->vm_start || end > vma->vm_end)
+                goto out;
+
+        /* Must set VM_NONLINEAR before any pages are populated. */
+        if (!(vma->vm_flags & VM_NONLINEAR)) {
+                /* Don't need a nonlinear mapping, exit success */
+                if (pgoff == linear_page_index(vma, start)) {
+                        err = 0;
+                        goto out;
+                }
+
+                if (!has_write_lock) {
+                        up_read(&mm->mmap_sem);
+                        down_write(&mm->mmap_sem);
+                        has_write_lock = 1;
+                        goto retry;
+                }
+                mapping = vma->vm_file->f_mapping;
+                spin_lock(&mapping->i_mmap_lock);
+                flush_dcache_mmap_lock(mapping);
+                vma->vm_flags |= VM_NONLINEAR;
+                vma_prio_tree_remove(vma, &mapping->i_mmap);
+                vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
+                flush_dcache_mmap_unlock(mapping);
+                spin_unlock(&mapping->i_mmap_lock);
+        }
+
+        if (vma->vm_flags & VM_CAN_NONLINEAR) {
+                err = populate_range(mm, vma, start, size, pgoff);
+                if (!err && !(flags & MAP_NONBLOCK)) {
+                        if (unlikely(has_write_lock)) {
+                                downgrade_write(&mm->mmap_sem);
+                                has_write_lock = 0;
                         }
-                        mapping = vma->vm_file->f_mapping;
-                        spin_lock(&mapping->i_mmap_lock);
-                        flush_dcache_mmap_lock(mapping);
-                        vma->vm_flags |= VM_NONLINEAR;
-                        vma_prio_tree_remove(vma, &mapping->i_mmap);
-                        vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
-                        flush_dcache_mmap_unlock(mapping);
-                        spin_unlock(&mapping->i_mmap_lock);
+                        make_pages_present(start, start+size);
                 }
+        } else
+                err = vma->vm_ops->populate(vma, start, size, vma->vm_page_prot,
+                                                pgoff, flags & MAP_NONBLOCK);
 
-                err = vma->vm_ops->populate(vma, start, size,
-                                            vma->vm_page_prot,
-                                            pgoff, flags & MAP_NONBLOCK);
+        /*
+         * We can't clear VM_NONLINEAR because we'd have to do
+         * it after ->populate completes, and that would prevent
+         * downgrading the lock.  (Locks can't be upgraded).
+         */
 
-                /*
-                 * We can't clear VM_NONLINEAR because we'd have to do
-                 * it after ->populate completes, and that would prevent
-                 * downgrading the lock.  (Locks can't be upgraded).
-                 */
-        }
+out:
         if (likely(!has_write_lock))
                 up_read(&mm->mmap_sem);
         else