3 files changed, 15 insertions, 5 deletions

diff --git a/kernel/range.c b/kernel/range.c
index 071b0ab455cb..eb911dbce267 100644
--- a/kernel/range.c
+++ b/kernel/range.c
@@ -48,9 +48,11 @@ int add_range_with_merge(struct range *range, int az, int nr_range,
                 final_start = min(range[i].start, start);
                 final_end = max(range[i].end, end);
 
-                range[i].start = final_start;
-                range[i].end =  final_end;
-                return nr_range;
+                /* clear it and add it back for further merge */
+                range[i].start = 0;
+                range[i].end =  0;
+                return add_range_with_merge(range, az, nr_range,
+                        final_start, final_end);
         }
 
         /* Need to add it: */
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index b59aea2c48c2..e444ff88f0a4 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -620,6 +620,9 @@ int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
         if (cpu == RING_BUFFER_ALL_CPUS)
                 work = &buffer->irq_work;
         else {
+                if (!cpumask_test_cpu(cpu, buffer->cpumask))
+                        return -EINVAL;
+
                 cpu_buffer = buffer->buffers[cpu];
                 work = &cpu_buffer->irq_work;
         }
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ae6fa2d1cdf7..4d79485b3237 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6216,10 +6216,15 @@ __init static int tracer_alloc_buffers(void)
 
         trace_init_cmdlines();
 
-        register_tracer(&nop_trace);
-
+        /*
+         * register_tracer() might reference current_trace, so it
+         * needs to be set before we register anything. This is
+         * just a bootstrap of current_trace anyway.
+         */
         global_trace.current_trace = &nop_trace;
 
+        register_tracer(&nop_trace);
+
         /* All seems OK, enable tracing */
         tracing_disabled = 0;