From c452b6b7f53f56fe3afa64ad2a3be344157ae9da Mon Sep 17 00:00:00 2001 From: Sumit Gupta Date: Thu, 22 Apr 2021 10:46:11 +0530 Subject: [PATCH 370/371] Revert "BACKPORT: sched/core: Fix rules for running on online && !active CPUs" X-NVConfidentiality: public This reverts commit e363fcd2ad4a5f4597f01512732204d5200cc123. Bug 200671224 --- kernel/sched/core.c | 42 ++++++++++++------------------------------ 1 file changed, 12 insertions(+), 30 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2178e83..553cced 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1045,33 +1045,6 @@ void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) } #ifdef CONFIG_SMP - -static inline bool is_per_cpu_kthread(struct task_struct *p) -{ - if (!(p->flags & PF_KTHREAD)) - return false; - - if (p->nr_cpus_allowed != 1) - return false; - - return true; -} - -/* - * Per-CPU kthreads are allowed to run on !actie && online CPUs, see - * __set_cpus_allowed_ptr() and select_fallback_rq(). - */ -static inline bool is_cpu_allowed(struct task_struct *p, int cpu) -{ - if (!cpumask_test_cpu(cpu, &p->cpus_allowed)) - return false; - - if (is_per_cpu_kthread(p)) - return cpu_online(cpu); - - return cpu_active(cpu); -} - /* * This is how migration works: * @@ -1129,8 +1102,16 @@ struct migration_arg { */ static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu) { + if (p->flags & PF_KTHREAD) { + if (unlikely(!cpu_online(dest_cpu))) + return rq; + } else { + if (unlikely(!cpu_active(dest_cpu))) + return rq; + } + /* Affinity changed (again). */ - if (!is_cpu_allowed(p, dest_cpu)) + if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) return rq; rq = move_queued_task(rq, p, dest_cpu); @@ -1757,9 +1738,10 @@ static int select_fallback_rq(int cpu, struct task_struct *p) for (;;) { /* Any allowed, online CPU? */ for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { - if (!is_cpu_allowed(p, dest_cpu)) + if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu)) + continue; + if (!cpu_online(dest_cpu)) continue; - goto out; } -- 2.7.4