sched: Fix hotplug vs. set_cpus_allowed_ptr()

sched: Fix hotplug vs. set_cpus_allowed_ptr()

Lai found that:

  WARNING: CPU: 1 PID: 13 at arch/x86/kernel/smp.c:124 native_smp_send_reschedule+0x2d/0x4b()
  ...
  migration_cpu_stop+0x1d/0x22

was caused by set_cpus_allowed_ptr() assuming that cpu_active_mask is
always a sub-set of cpu_online_mask.

This isn't true since 5fbd036b552f ("sched: Cleanup cpu_active madness").

So set active and online at the same time to avoid this particular
problem.

Fixes: 5fbd036b552f ("sched: Cleanup cpu_active madness")
Signed-off-by: Lai Jiangshan <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Gautham R. Shenoy <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Michael wang <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Srivatsa S. Bhat <[email protected]>
Cc: Toshi Kani <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>