Merge "sched: Ensure proper task migration when a CPU is isolated" (76438748) · Commits · e / devices / android_kernel_sony_msm8998

kernel/sched/core.c

+40 −6

Original line number	Diff line number	Diff line
		@@ -5463,6 +5463,37 @@ static struct task_struct fake_task = {
		.sched_class = &fake_sched_class,
		};

		/*
		* Remove a task from the runqueue and pretend that it's migrating. This
		* should prevent migrations for the detached task and disallow further
		* changes to tsk_cpus_allowed.
		*/
		static void
		detach_one_task(struct task_struct p, struct rq rq, struct list_head *tasks)
		{
		lockdep_assert_held(&rq->lock);

		p->on_rq = TASK_ON_RQ_MIGRATING;
		deactivate_task(rq, p, 0);
		list_add(&p->se.group_node, tasks);
		}

		static void attach_tasks(struct list_head tasks, struct rq rq)
		{
		struct task_struct *p;

		lockdep_assert_held(&rq->lock);

		while (!list_empty(tasks)) {
		p = list_first_entry(tasks, struct task_struct, se.group_node);
		list_del_init(&p->se.group_node);

		BUG_ON(task_rq(p) != rq);
		activate_task(rq, p, 0);
		p->on_rq = TASK_ON_RQ_QUEUED;
		}
		}

		/*
		* Migrate all tasks (not pinned if pinned argument say so) from the rq,
		* sleeping tasks will be migrated by try_to_wake_up()->select_task_rq().
		@@ -5477,6 +5508,7 @@ static void migrate_tasks(struct rq *dead_rq, bool migrate_pinned_tasks)
		struct task_struct next, stop = rq->stop;
		int dest_cpu;
		unsigned int num_pinned_kthreads = 1; /* this thread */
		LIST_HEAD(tasks);
		cpumask_t avail_cpus;

		cpumask_andnot(&avail_cpus, cpu_online_mask, cpu_isolated_mask);
		@@ -5501,12 +5533,10 @@ static void migrate_tasks(struct rq *dead_rq, bool migrate_pinned_tasks)

		for (;;) {
		/*
		* There's this thread running + pinned threads, bail when
		* that's the only remaining threads.
		* There's this thread running, bail when that's the only
		* remaining thread.
		*/
		if ((migrate_pinned_tasks && rq->nr_running == 1) \|\|
		(!migrate_pinned_tasks &&
		rq->nr_running <= num_pinned_kthreads))
		if (rq->nr_running == 1)
		break;

		/*
		@@ -5519,8 +5549,9 @@ static void migrate_tasks(struct rq *dead_rq, bool migrate_pinned_tasks)

		if (!migrate_pinned_tasks && next->flags & PF_KTHREAD &&
		!cpumask_intersects(&avail_cpus, &next->cpus_allowed)) {
		lockdep_unpin_lock(&rq->lock);
		detach_one_task(next, rq, &tasks);
		num_pinned_kthreads += 1;
		lockdep_unpin_lock(&rq->lock);
		continue;
		}

		@@ -5568,6 +5599,9 @@ static void migrate_tasks(struct rq *dead_rq, bool migrate_pinned_tasks)
		}

		rq->stop = stop;

		if (num_pinned_kthreads > 1)
		attach_tasks(&tasks, rq);
		}

		static void set_rq_online(struct rq *rq);

kernel/sched/rt.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -1970,11 +1970,11 @@ retry:
		goto retry;
		}

		deactivate_task(rq, next_task, 0);
		next_task->on_rq = TASK_ON_RQ_MIGRATING;
		deactivate_task(rq, next_task, 0);
		set_task_cpu(next_task, lowest_rq->cpu);
		next_task->on_rq = TASK_ON_RQ_QUEUED;
		activate_task(lowest_rq, next_task, 0);
		next_task->on_rq = TASK_ON_RQ_QUEUED;
		ret = 1;

		resched_curr(lowest_rq);
		@@ -2226,11 +2226,11 @@ static void pull_rt_task(struct rq *this_rq)

		resched = true;

		deactivate_task(src_rq, p, 0);
		p->on_rq = TASK_ON_RQ_MIGRATING;
		deactivate_task(src_rq, p, 0);
		set_task_cpu(p, this_cpu);
		p->on_rq = TASK_ON_RQ_QUEUED;
		activate_task(this_rq, p, 0);
		p->on_rq = TASK_ON_RQ_QUEUED;
		/*
		* We continue with the search, just in
		* case there's an even higher prio task