Pull tracing fix from Steven Rostedt:
 "Eiichi Tsukata found a small bug from the fixup of the stack code

  Removing ULONG_MAX as the marker for the user stack trace end, made
  the tracing code not know where the end is. The end is now marked with
  a zero (NULL) pointer. Eiichi fixed this in the tracing code"

* tag 'trace-v5.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix user stack trace "??" output