From 4ff9083b8a9a80bdf4ebbbec22cda4cbfb60f7aa Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 7 Sep 2017 17:03:52 +0200 Subject: [PATCH] sched/core: WARN() when migrating to an offline CPU Migrating tasks to offline CPUs is a pretty big fail, warn about it. Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170907150614.094206976@infradead.org Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 136a76d80dbf..18a6966567da 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1173,6 +1173,10 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || lockdep_is_held(&task_rq(p)->lock))); #endif + /* + * Clearly, migrating tasks to offline CPUs is a fairly daft thing. + */ + WARN_ON_ONCE(!cpu_online(new_cpu)); #endif trace_sched_migrate_task(p, new_cpu); -- 2.20.1