---+        +---+        +---+

     ^            ^            ^
      \           |            /
       ------- Buffer---------

If we perform a list_del_init() on the reader page we will actually remove
the last page the reader swapped with and not the reader page itself.
This will cause that page to not be freed, and thus is a memory leak.

Luckily, the only user of the ring buffer so far is ftrace. And ftrace
will not free its ring buffer after it allocates it. There is no current
possible memory leak. But once there are other users, or if ftrace
dynamically creates and frees its ring buffer, then this would be a
memory leak.

This patch fixes the leak for future cases.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
+I&(’-x