From 0298f03cf8ee54b74e2971d90f88e6f601c9d3bd Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 26 Aug 2021 15:37:38 +0200 Subject: [PATCH] sched: Fix get_push_task() vs migrate_disable() [ Upstream commit e681dcbaa4b284454fecd09617f8b24231448446 ] push_rt_task() attempts to move the currently running task away if the next runnable task has migration disabled and therefore is pinned on the current CPU. The current task is retrieved via get_push_task() which only checks for nr_cpus_allowed == 1, but does not check whether the task has migration disabled and therefore cannot be moved either. The consequence is a pointless invocation of the migration thread which correctly observes that the task cannot be moved. Return NULL if the task has migration disabled and cannot be moved to another CPU. Fixes: a7c81556ec4d3 ("sched: Fix migrate_disable() vs rt/dl balancing") Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20210826133738.yiotqbtdaxzjsnfj@linutronix.de Signed-off-by: Sasha Levin --- kernel/sched/sched.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 35f7efed75c4c..f2bc99ca01e57 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1977,6 +1977,9 @@ static inline struct task_struct *get_push_task(struct rq *rq) if (p->nr_cpus_allowed == 1) return NULL; + if (p->migration_disabled) + return NULL; + rq->push_busy = true; return get_task_struct(p); } -- 2.47.2