In preparation for the ring-buffer memory mapping where each subbuf will
be accessible to user-space, zero all the page allocations.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 173d2595ce2d..db73e326fa04 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1466,7 +1466,8 @@ static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
 
 		list_add(&bpage->list, pages);
 
-		page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu), mflags,
+		page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu),
+					mflags | __GFP_ZERO,
 					cpu_buffer->buffer->subbuf_order);
 		if (!page)
 			goto free_pages;
@@ -1551,7 +1552,8 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu)
 
 	cpu_buffer->reader_page = bpage;
 
-	page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, cpu_buffer->buffer->subbuf_order);
+	page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_ZERO,
+				cpu_buffer->buffer->subbuf_order);
 	if (!page)
 		goto fail_free_reader;
 	bpage->page = page_address(page);
@@ -5525,7 +5527,8 @@ ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu)
 	if (bpage->data)
 		goto out;
 
-	page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_NORETRY,
+	page = alloc_pages_node(cpu_to_node(cpu),
+				GFP_KERNEL | __GFP_NORETRY | __GFP_ZERO,
 				cpu_buffer->buffer->subbuf_order);
 	if (!page) {
 		kfree(bpage);
-- 
2.43.0.429.g432eaa2c6b-goog