From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: [PATCH RT 20/22] sched: Allow pinned user tasks to be awakened to the CPU they pinned Date: Wed, 05 Sep 2018 08:28:14 -0400 Message-ID: <20180905122837.674583106@goodmis.org> References: <20180905122754.443196118@goodmis.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , Julia Cartwright , Daniel Wagner , tom.zanussi@linux.intel.com, stable-rt@vger.kernel.org, Mike Galbraith To: linux-kernel@vger.kernel.org, linux-rt-users Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org 4.14.63-rt41-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Galbraith [ Upstream commit cd4d35ef89948221f7cd1751cee453943967364c ] Since commit 7af443ee16976 ("sched/core: Require cpu_active() in select_task_rq(), for user tasks") select_fallback_rq() will BUG() if the CPU to which a task has pinned itself and pinned becomes !cpu_active() while it slept. The task will continue running on the to-be-removed CPU and will remove itself from the CPU during takedown_cpu() (while cpuhp_pin_lock will be acquired) and move to another CPU based on its mask after the migrate_disable() section has been left. Cc: stable-rt@vger.kernel.org Signed-off-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a5ce37b90fca..6e6bd5262f23 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -980,7 +980,7 @@ static inline bool is_cpu_allowed(struct task_struct *p, int cpu) if (!cpumask_test_cpu(cpu, p->cpus_ptr)) return false; - if (is_per_cpu_kthread(p)) + if (is_per_cpu_kthread(p) || __migrate_disabled(p)) return cpu_online(cpu); return cpu_active(cpu); -- 2.18.0