| From 386ef214c3c6ab111d05e1790e79475363abaa05 Mon Sep 17 00:00:00 2001 |
| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Date: Thu, 17 Mar 2022 15:51:32 +0100 |
| Subject: sched: Teach the forced-newidle balancer about CPU affinity limitation. |
| |
| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| |
| commit 386ef214c3c6ab111d05e1790e79475363abaa05 upstream. |
| |
| try_steal_cookie() looks at task_struct::cpus_mask to decide if the |
| task could be moved to `this' CPU. It ignores that the task might be in |
| a migration disabled section while not on the CPU. In this case the task |
| must not be moved otherwise per-CPU assumption are broken. |
| |
| Use is_cpu_allowed(), as suggested by Peter Zijlstra, to decide if the a |
| task can be moved. |
| |
| Fixes: d2dfa17bc7de6 ("sched: Trivial forced-newidle balancer") |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Link: https://lkml.kernel.org/r/YjNK9El+3fzGmswf@linutronix.de |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| kernel/sched/core.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/kernel/sched/core.c |
| +++ b/kernel/sched/core.c |
| @@ -5889,7 +5889,7 @@ static bool try_steal_cookie(int this, i |
| if (p == src->core_pick || p == src->curr) |
| goto next; |
| |
| - if (!cpumask_test_cpu(this, &p->cpus_mask)) |
| + if (!is_cpu_allowed(p, this)) |
| goto next; |
| |
| if (p->core_occupation > dst->idle->core_occupation) |
