From 6ee9d109869847548ea108dab1e27a07541687bc Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 29 Nov 2021 18:46:44 +0100
Subject: [PATCH] sched: Trigger warning if ->migration_disabled counter
underflows.
References: bnc#1189998 (PREEMPT_RT prerequisite backports)
Patch-mainline: v5.17
Git-commit: 9d0df37797453f168afdb2e6fd0353c73718ae9a
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
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
kernel/sched/core.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9042bf925166..b6981a9cd18b 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().