Messages in this thread Patch in this message | | | Date | Fri, 07 Sep 2018 16:59:18 -0400 | From | Steven Rostedt <> | Subject | [PATCH RT 21/24] sched: Allow pinned user tasks to be awakened to the CPU they pinned |
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4.14.63-rt41-rc2 stable review patch. If anyone has any objections, please let me know.
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From: Mike Galbraith <efault@gmx.de>
[ 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 <efault@gmx.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- 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
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