1 files changed, 17 insertions, 2 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 7f6059c5aa94..1da7b6ea8b85 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1768,6 +1768,14 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer,
          * must fill the old tail_page with padding.
          */
         if (tail >= BUF_PAGE_SIZE) {
+                /*
+                 * If the page was filled, then we still need
+                 * to update the real_end. Reset it to zero
+                 * and the reader will ignore it.
+                 */
+                if (tail == BUF_PAGE_SIZE)
+                        tail_page->real_end = 0;
+
                 local_sub(length, &tail_page->write);
                 return;
         }
@@ -3894,12 +3902,12 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
         ret = read;
 
         cpu_buffer->lost_events = 0;
+
+        commit = local_read(&bpage->commit);
         /*
          * Set a flag in the commit field if we lost events
          */
         if (missed_events) {
-                commit = local_read(&bpage->commit);
-
                 /* If there is room at the end of the page to save the
                  * missed events, then record it there.
                  */
@@ -3907,10 +3915,17 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
                         memcpy(&bpage->data[commit], &missed_events,
                                sizeof(missed_events));
                         local_add(RB_MISSED_STORED, &bpage->commit);
+                        commit += sizeof(missed_events);
                 }
                 local_add(RB_MISSED_EVENTS, &bpage->commit);
         }
 
+        /*
+         * This page may be off to user land. Zero it out here.
+         */
+        if (commit < BUF_PAGE_SIZE)
+                memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit);
+
  out_unlock:
         spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);