linux-kernel - [PATCH v1] cpufreq: Drop policy locking from cpufreq_policy_is_good_for

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Message-ID: <2806514.mvXUDI8C0e@rjwysocki.net>
Date: Mon, 12 May 2025 15:23:30 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Lukasz Luba <lukasz.luba@....com>,
 Dietmar Eggemann <dietmar.eggemann@....com>,
 Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
 Christian Loehle <christian.loehle@....com>,
 Marek Szyprowski <m.szyprowski@...sung.com>
Subject:
 [PATCH v1] cpufreq: Drop policy locking from cpufreq_policy_is_good_for_eas()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Policy locking was added to cpufreq_policy_is_good_for_eas() by commit
4854649b1fb4 ("cpufreq/sched: Move cpufreq-specific EAS checks to
cpufreq") to address a theoretical race condition, but it turned out to
introduce a circular locking dependency between the policy rwsem and
sched_domains_mutex via cpuset_mutex. This leads to a board lockup on
OdroidN2 that is based on the ARM64 Amlogic Meson SoC.

Drop the policy locking from cpufreq_policy_is_good_for_eas() to address
this issue.

Fixes: 4854649b1fb4 ("cpufreq/sched: Move cpufreq-specific EAS checks to cpufreq")
Closes: https://lore.kernel.org/linux-pm/1bf3df62-0641-459f-99fc-fd511e564b84@samsung.com/
Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/cpufreq.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -3067,8 +3067,6 @@
 		return false;
 	}

-	guard(cpufreq_policy_read)(policy);
-
 	return sugov_is_governor(policy);
 }