Pull thread fixes from Christian Brauner:
 "Here are two fixes:

   - Panic earlier when global init exits to generate useable coredumps.

     Currently, when global init and all threads in its thread-group
     have exited we panic via:

       do_exit()
       -> exit_notify()
          -> forget_original_parent()
             -> find_child_reaper()

     This makes it hard to extract a useable coredump for global init
     from a kernel crashdump because by the time we panic exit_mm() will
     have already released global init's mm. We now panic slightly
     earlier. This has been a problem in certain environments such as
     Android.

   - Fix a race in assigning and reading taskstats for thread-groups
     with more than one thread.

     This patch has been waiting for quite a while since people
     disagreed on what the correct fix was at first"

* tag 'for-linus-2020-01-03' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  exit: panic before exit_mm() on global init exit
  taskstats: fix data-race