mm: use vm_unmapped_area() on alpha architecture

Update the alpha arch_get_unmapped_area function to make use of
vm_unmapped_area() instead of implementing a brute force search.

Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/alpha/kernel/osf_sys.c

@@ -1300,17 +1300,15 @@ static unsigned long
 arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
 		         unsigned long limit)
 {
-	struct vm_area_struct *vma = find_vma(current->mm, addr);
+	struct vm_unmapped_area_info info;
 
-	while (1) {
-		/* At this point:  (!vma || addr < vma->vm_end). */
-		if (limit - len < addr)
-			return -ENOMEM;
-		if (!vma || addr + len <= vma->vm_start)
-			return addr;
-		addr = vma->vm_end;
-		vma = vma->vm_next;
-	}
+	info.flags = 0;
+	info.length = len;
+	info.low_limit = addr;
+	info.high_limit = limit;
+	info.align_mask = 0;
+	info.align_offset = 0;
+	return vm_unmapped_area(&info);
 }
 
 unsigned long