[PATCH] madvise() does not always return -EBADF on non-file mapped area

The madvise() system call returns -EBADF for areas which does not map to
files, only for *behaviour* request MADV_WILLNEED.

According to man pages, madvise returns :

EBADF - the map exists, but the area maps something that isn't a file.

Fixes bug 2995.
Signed-off-by: NSuzuki K P <suzuki@in.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

mm/madvise.c

@@ -83,9 +83,6 @@ static long madvise_willneed(struct vm_area_struct * vma,
 {
 	struct file *file = vma->vm_file;
 
-	if (!file)
-		return -EBADF;
-
 	if (file->f_mapping->a_ops->get_xip_page) {
 		/* no bad return value, but ignore advice */
 		return 0;
@@ -140,11 +137,16 @@ static long madvise_dontneed(struct vm_area_struct * vma,
 	return 0;
 }
 
-static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
-			unsigned long start, unsigned long end, int behavior)
+static long
+madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
+		unsigned long start, unsigned long end, int behavior)
 {
+	struct file *filp = vma->vm_file;
 	long error = -EBADF;
 
+	if (!filp)
+		goto  out;
+
 	switch (behavior) {
 	case MADV_NORMAL:
 	case MADV_SEQUENTIAL:
@@ -165,6 +167,7 @@ static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev
 		break;
 	}
 		
+out:
 	return error;
 }