From: Peter Zijlstra Date: Fri, 4 Dec 2009 08:59:02 +0000 (+0100) Subject: sched: Fix task priority bug X-Git-Tag: firefly_0821_release~11625^2~303 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=26931397cc71bcac187efdcd2fc43ce0d41e4eb0;p=firefly-linux-kernel-4.4.55.git sched: Fix task priority bug commit 57785df5ac53c70da9fb53696130f3c551bfe1f9 upstream. 83f9ac removed a call to effective_prio() in wake_up_new_task(), which leads to tasks running at MAX_PRIO. This is caused by the idle thread being set to MAX_PRIO before forking off init. O(1) used that to make sure idle was always preempted, CFS uses check_preempt_curr_idle() for that so we can savely remove this bit of legacy code. Reported-by: Mike Galbraith Tested-by: Mike Galbraith Signed-off-by: Peter Zijlstra LKML-Reference: <1259754383.4003.610.camel@laptop> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/sched.c b/kernel/sched.c index dd0dccde5df0..bf841d85b9ba 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3177,10 +3177,6 @@ static void pull_task(struct rq *src_rq, struct task_struct *p, deactivate_task(src_rq, p, 0); set_task_cpu(p, this_cpu); activate_task(this_rq, p, 0); - /* - * Note that idle threads have a prio of MAX_PRIO, for this test - * to be always true for them. - */ check_preempt_curr(this_rq, p, 0); } @@ -6982,7 +6978,6 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu) __sched_fork(idle); idle->se.exec_start = sched_clock(); - idle->prio = idle->normal_prio = MAX_PRIO; cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu)); __set_task_cpu(idle, cpu); @@ -7686,7 +7681,6 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) spin_lock_irq(&rq->lock); update_rq_clock(rq); deactivate_task(rq, rq->idle, 0); - rq->idle->static_prio = MAX_PRIO; __setscheduler(rq, rq->idle, SCHED_NORMAL, 0); rq->idle->sched_class = &idle_sched_class; migrate_dead_tasks(cpu);