sched/fair: Avoid newidle balance for !active CPUs
authorPeter Zijlstra <peterz@infradead.org>
Thu, 7 Sep 2017 15:03:50 +0000 (17:03 +0200)
committerIngo Molnar <mingo@kernel.org>
Tue, 12 Sep 2017 15:41:03 +0000 (17:41 +0200)
commit2800486ee34825d954f64c6f98037daea328f121
treeb734003f0085ce39c7688259c7aeb6617ccff6e4
parent46123355af729514e6fa8b8a9dd1e645e61a6466
sched/fair: Avoid newidle balance for !active CPUs

On CPU hot unplug, when parking the last kthread we'll try and
schedule into idle to kill the CPU. This last schedule can (and does)
trigger newidle balance because at this point the sched domains are
still up because of commit:

  77d1dfda0e79 ("sched/topology, cpuset: Avoid spurious/wrong domain rebuilds")

Obviously pulling tasks to an already offline CPU is a bad idea, and
all balancing operations _should_ be subject to cpu_active_mask, make
it so.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 77d1dfda0e79 ("sched/topology, cpuset: Avoid spurious/wrong domain rebuilds")
Link: http://lkml.kernel.org/r/20170907150613.994135806@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/sched/fair.c