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