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 <[email protected]> Debugged-by: Valentin Schneider <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
nathanchance · Nov 19, 2020 · 1293771 · 1293771
1 parent d707faa
commit 1293771
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
@@ -1911,7 +1911,7 @@ 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;
 			}
 
@@ -1950,7 +1950,7 @@ 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;
 		}