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From 5857482efa6b272402feb4b063c4273e70dd67fb Mon Sep 17 00:00:00 2001
From: Valentin Schneider <valentin.schneider@arm.com>
Date: Fri, 23 Oct 2020 12:12:16 +0200
Subject: [PATCH 019/323] sched: Deny self-issued __set_cpus_allowed_ptr() when
migrate_disable()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
migrate_disable();
set_cpus_allowed_ptr(current, {something excluding task_cpu(current)});
affine_move_task(); <-- never returns
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201013140116.26651-1-valentin.schneider@arm.com
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/sched/core.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b5f35b512577..3b7bb01eecc0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2254,8 +2254,17 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
goto out;
}
- if (!(flags & SCA_MIGRATE_ENABLE) && cpumask_equal(&p->cpus_mask, new_mask))
- goto out;
+ if (!(flags & SCA_MIGRATE_ENABLE)) {
+ if (cpumask_equal(&p->cpus_mask, new_mask))
+ goto out;
+
+ if (WARN_ON_ONCE(p == current &&
+ is_migration_disabled(p) &&
+ !cpumask_test_cpu(task_cpu(p), new_mask))) {
+ ret = -EBUSY;
+ goto out;
+ }
+ }
/*
* Picking a ~random cpu helps in cases where we are changing affinity
--
2.43.0
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