[PATCH] sched: disable interrupts for locking in load_balance()

/*

 * Check this_cpu to ensure it is balanced within domain. Attempt to move

 * tasks if there is an imbalance.

 *

 * Called with this_rq unlocked.

 */

static int load_balance(int this_cpu, struct rq *this_rq,

			struct sched_domain *sd, enum idle_type idle)

	unsigned long imbalance;

	struct rq *busiest;

	cpumask_t cpus = CPU_MASK_ALL;

	unsigned long flags;

	/*

	 * When power savings policy is enabled for the parent domain, idle

		 * still unbalanced. nr_moved simply stays zero, so it is

		 * correctly treated as an imbalance.

		 */

		local_irq_save(flags);

		double_rq_lock(this_rq, busiest);

		nr_moved = move_tasks(this_rq, this_cpu, busiest,

				      minus_1_or_zero(busiest->nr_running),

				      imbalance, sd, idle, &all_pinned);

		double_rq_unlock(this_rq, busiest);

		local_irq_restore(flags);

		/* All tasks on this runqueue were pinned by CPU affinity */

		if (unlikely(all_pinned)) {

		if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {

			spin_lock(&busiest->lock);

			spin_lock_irqsave(&busiest->lock, flags);

			/* don't kick the migration_thread, if the curr

			 * task on busiest cpu can't be moved to this_cpu

			 */

			if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) {

				spin_unlock(&busiest->lock);

				spin_unlock_irqrestore(&busiest->lock, flags);

				all_pinned = 1;

				goto out_one_pinned;

			}

				busiest->push_cpu = this_cpu;

				active_balance = 1;

			}

			spin_unlock(&busiest->lock);

			spin_unlock_irqrestore(&busiest->lock, flags);

			if (active_balance)

				wake_up_process(busiest->migration_thread);