fix:
 kernel/trace/ring_buffer.c: In function ‘rb_allocate_pages’:
 kernel/trace/ring_buffer.c:235: error: ‘cpu’ undeclared (first use in this function)
 kernel/trace/ring_buffer.c:235: error: (Each undeclared identifier is reported only once
 kernel/trace/ring_buffer.c:235: error: for each function it appears in.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
 
        for (i = 0; i < nr_pages; i++) {
                page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()),
-                                   GFP_KERNEL, cpu_to_node(cpu));
+                                   GFP_KERNEL, cpu_to_node(i));
                if (!page)
                        goto free_pages;
                list_add(&page->list, &pages);