From 97e224dc8fceb3d87ce2ddf6e2a3a96b469dc7a7 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 12 Aug 2021 14:40:05 +0200
Subject: [PATCH 078/166] sched: Trigger warning if ->migration_disabled
 counter underflows.

If migrate_enable() is used more often than its counter part then it
remains undetected and rq::nr_pinned will underflow, too.

Add a warning if migrate_enable() is attempted if without a matching a
migrate_disable().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/sched/core.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-5.15.13-rt26/kernel/sched/core.c
===================================================================
@ linux-5.15.13-rt26/kernel/sched/core.c:2156 @ void migrate_enable(void)
 	if (p->migration_disabled > 1) {
 		p->migration_disabled--;
 		return;
+	} else if (WARN_ON_ONCE(p->migration_disabled == 0)) {
+		return;
 	}
 
 	/*