linux-kernel - Re: [syzbot] possible deadlock in wake_up_all_idle

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Message-ID: <20211019190811.ubam63tfv33c7lmx@linutronix.de>
Date:   Tue, 19 Oct 2021 21:08:11 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     syzbot <syzbot+d5b23b18d2f4feae8a67@...kaller.appspotmail.com>
Cc:     bristot@...hat.com, bsegall@...gle.com, dietmar.eggemann@....com,
        gor@...ux.ibm.com, jgross@...e.com, juri.lelli@...hat.com,
        linux-kernel@...r.kernel.org, mgorman@...e.de, mingo@...nel.org,
        mingo@...hat.com, namit@...are.com, peterz@...radead.org,
        rdunlap@...radead.org, rostedt@...dmis.org,
        syzkaller-bugs@...glegroups.com, vincent.guittot@...aro.org
Subject: Re: [syzbot] possible deadlock in wake_up_all_idle_cpus

Does this do anything useful?

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/smp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index ad0b68a3a3d36..b3bf528fa14d3 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -1170,14 +1170,14 @@ void wake_up_all_idle_cpus(void)
 {
 	int cpu;
 
-	cpus_read_lock();
+	migrate_disable();
 	for_each_online_cpu(cpu) {
 		if (cpu == raw_smp_processor_id())
 			continue;
 
 		wake_up_if_idle(cpu);
 	}
-	cpus_read_unlock();
+	migrate_enable();
 }
 EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
 
-- 
2.33.0