From 7938cd4e83d2c3dfa9792f0d1132664119780866 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 17 Nov 2020 12:14:51 +0100
Subject: [PATCH 022/327] sched: Fix migration_cpu_stop() WARN

Oleksandr reported hitting the WARN in the 'task_rq(p) != rq' branch
of migration_cpu_stop(). Valentin noted that using cpu_of(rq) in that
case is just plain wrong to begin with, since per the earlier branch
that isn't the actual CPU of the task.

Replace both instances of is_cpu_allowed() by a direct p->cpus_mask
test using task_cpu().

Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Debugged-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/sched/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e9ecd36539b4..0c374eea1dd9 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1928,7 +1928,7 @@ static int migration_cpu_stop(void *data)
 			 * and we should be valid again. Nothing to do.
 			 */
 			if (!pending) {
-				WARN_ON_ONCE(!is_cpu_allowed(p, cpu_of(rq)));
+				WARN_ON_ONCE(!cpumask_test_cpu(task_cpu(p), &p->cpus_mask));
 				goto out;
 			}
 
@@ -1956,7 +1956,7 @@ static int migration_cpu_stop(void *data)
 		 * valid again. Nothing to do.
 		 */
 		if (!pending) {
-			WARN_ON_ONCE(!is_cpu_allowed(p, cpu_of(rq)));
+			WARN_ON_ONCE(!cpumask_test_cpu(task_cpu(p), &p->cpus_mask));
 			goto out;
 		}
 
-- 
2.49.0

