From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 29 Nov 2021 17:46:44 +0000 (+0100)
Subject: sched: Trigger warning if ->migration_disabled counter underflows.
X-Git-Tag: v5.17-rc1~120^2~16
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9d0df37797453f168afdb2e6fd0353c73718ae9a;p=thirdparty%2Fkernel%2Fstable.git

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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211129174654.668506-2-bigeasy@linutronix.de
---

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3c9b0fda64ac0..300218ad98a24 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2173,6 +2173,9 @@ void migrate_enable(void)
 		return;
 	}
 
+	if (WARN_ON_ONCE(!p->migration_disabled))
+		return;
+
 	/*
 	 * Ensure stop_task runs either before or after this, and that
 	 * __set_cpus_allowed_ptr(SCA_MIGRATE_ENABLE) doesn't schedule().