Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 update from Martin Schwidefsky:
 "One small improvement for the cputime accounting, two bug fixes and an
  update for the default configuration files"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/ftrace: add ftrace_graph_is_dead() check
  s390: update default configuration
  s390/vdso: fix stack corruption
  s390/time: use stck clock fast for do_account_vtime