linux-kernel - [PATCH v2 3/3] kfence: use power-efficient work queue to run delayed work

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Date:   Wed, 21 Apr 2021 12:51:32 +0200
From:   Marco Elver <elver@...gle.com>
To:     elver@...gle.com, akpm@...ux-foundation.org
Cc:     glider@...gle.com, dvyukov@...gle.com, jannh@...gle.com,
        mark.rutland@....com, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, kasan-dev@...glegroups.com, hdanton@...a.com
Subject: [PATCH v2 3/3] kfence: use power-efficient work queue to run delayed work

Use the power-efficient work queue, to avoid the pathological case where
we keep pinning ourselves on the same possibly idle CPU on systems that
want to be power-efficient [1].
[1] https://lwn.net/Articles/731052/

Signed-off-by: Marco Elver <elver@...gle.com>
---
 mm/kfence/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 9742649f3f88..e18fbbd5d9b4 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -636,7 +636,8 @@ static void toggle_allocation_gate(struct work_struct *work)
 	/* Disable static key and reset timer. */
 	static_branch_disable(&kfence_allocation_key);
 #endif
-	schedule_delayed_work(&kfence_timer, msecs_to_jiffies(kfence_sample_interval));
+	queue_delayed_work(system_power_efficient_wq, &kfence_timer,
+			   msecs_to_jiffies(kfence_sample_interval));
 }
 static DECLARE_DELAYED_WORK(kfence_timer, toggle_allocation_gate);
 
@@ -665,7 +666,7 @@ void __init kfence_init(void)
 	}
 
 	WRITE_ONCE(kfence_enabled, true);
-	schedule_delayed_work(&kfence_timer, 0);
+	queue_delayed_work(system_power_efficient_wq, &kfence_timer, 0);
 	pr_info("initialized - using %lu bytes for %d objects at 0x%p-0x%p\n", KFENCE_POOL_SIZE,
 		CONFIG_KFENCE_NUM_OBJECTS, (void *)__kfence_pool,
 		(void *)(__kfence_pool + KFENCE_POOL_SIZE));
-- 
2.31.1.368.gbe11c130af-goog