Merge branch 'perf-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip

* 'perf-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip:
  x86, perf: Check that current->mm is alive before getting user callchain
  perf_event: Fix broken calc_timer_values()
  perf events: Fix slow and broken cgroup context switch code