From: Scott Wood <[email protected]> commit adfa969d4cfcc995a9d866020124e50f1827d2d1 in linux-rt-devel.
migrate_enable() currently open-codes a variant of select_fallback_rq(). However, it does not have the "No more Mr. Nice Guy" fallback and thus it will pass an invalid CPU to the migration thread if cpus_mask only contains a CPU that is !active. Signed-off-by: Scott Wood <[email protected]> Signed-off-by: Sebastian Andrzej Siewior <[email protected]> Signed-off-by: Paul Gortmaker <[email protected]> diff --git a/kernel/sched/core.c b/kernel/sched/core.c index fb4e86e6ff20..af1a51cbcf65 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7416,6 +7416,7 @@ void migrate_enable(void) if (p->migrate_disable_update) { struct rq *rq; struct rq_flags rf; + int cpu = task_cpu(p); rq = task_rq_lock(p, &rf); update_rq_clock(rq); @@ -7425,21 +7426,15 @@ void migrate_enable(void) p->migrate_disable_update = 0; - WARN_ON(smp_processor_id() != task_cpu(p)); - if (!cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) { - const struct cpumask *cpu_valid_mask = cpu_active_mask; - struct migration_arg arg; - unsigned int dest_cpu; - - if (p->flags & PF_KTHREAD) { - /* - * Kernel threads are allowed on online && !active CPUs - */ - cpu_valid_mask = cpu_online_mask; - } - dest_cpu = cpumask_any_and(cpu_valid_mask, &p->cpus_mask); - arg.task = p; - arg.dest_cpu = dest_cpu; + WARN_ON(smp_processor_id() != cpu); + if (!cpumask_test_cpu(cpu, &p->cpus_mask)) { + struct migration_arg arg = { p }; + struct rq_flags rf; + + rq = task_rq_lock(p, &rf); + update_rq_clock(rq); + arg.dest_cpu = select_fallback_rq(cpu, p); + task_rq_unlock(rq, p, &rf); unpin_current_cpu(); preempt_lazy_enable(); -- 2.7.4
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