sched/core: Check tgid in is_global_init()

Our global init task can have sub-threads, so ->pid check is not reliable
enough for is_global_init(), we need to check tgid instead. This has been
spotted by Oleg and a fix was proposed by Richard a long time ago (see the
link below).

Oleg wrote:

  : Because is_global_init() is only true for the main thread of /sbin/init.
  :
  : Just look at oom_unkillable_task(). It tries to not kill init. But, say,
  : select_bad_process() can happily find a sub-thread of is_global_init()
  : and still kill it.

I recently hit the problem in question; re-sending the patch (to the
best of my knowledge it has never been submitted) with updated function
comment. Credit goes to Oleg and Richard.

Suggested-by: Richard Guy Briggs <[email protected]>
Reported-by: Oleg Nesterov <[email protected]>
Signed-off-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Serge Hallyn <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Eric W . Biederman <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Serge E . Hallyn <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://www.redhat.com/archives/linux-audit/2013-December/msg00086.html
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions