sched/debug: Use task_pid_nr_ns in /proc/$pid/sched

It appears as though the addition of the PID namespace did not update
the output code for /proc/*/sched, which resulted in it providing PIDs
that were not self-consistent with the /proc mount. This additionally
made it trivial to detect whether a process was inside &init_pid_ns from
userspace, making container detection trivial:

   https://github.com/jessfraz/amicontained

This leads to situations such as:

  % unshare -pmf
  % mount -t proc proc /proc
  % head -n1 /proc/1/sched
  head (10047, #threads: 1)

Fix this by just using task_pid_nr_ns for the output of /proc/*/sched.
All of the other uses of task_pid_nr in kernel/sched/debug.c are from a
sysctl context and thus don't need to be namespaced.

Signed-off-by: Aleksa Sarai <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Eric W. Biederman <[email protected]>
Cc: Jess Frazelle <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions