ring-buffer: Fix memleak in ring_buffer_free()

I noticed oprofile memleaked in linux-2.6 current tree,
and tracked this ring-buffer leak.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
LKML-Reference: <4A7C06B9.2090302@gmail.com>
Cc: stable@kernel.org
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

kernel/trace/ring_buffer.c

@@ -735,6 +735,7 @@ ring_buffer_free(struct ring_buffer *buffer)
 
 	put_online_cpus();
 
+	kfree(buffer->buffers);
 	free_cpumask_var(buffer->cpumask);
 
 	kfree(buffer);