diff --git a/mm/madvise.c b/mm/madvise.c
index 464282e24a30f7cb5c33d2ed7a2c7216d383ae0b..1369e6d062bc345662c2a432d4f3ec5603e639ac 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -308,9 +308,9 @@ static long madvise_willneed(struct vm_area_struct *vma,
 	 */
 	*prev = NULL;	/* tell sys_madvise we drop mmap_sem */
 	get_file(file);
-	up_read(&current->mm->mmap_sem);
 	offset = (loff_t)(start - vma->vm_start)
 			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
+	up_read(&current->mm->mmap_sem);
 	vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
 	fput(file);
 	down_read(&current->mm->mmap_sem);