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

From: Marco Elver <elver@google.com>
To: elver@google.com, akpm@linux-foundation.org
Cc: glider@google.com, dvyukov@google.com, jannh@google.com,
	mark.rutland@arm.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, kasan-dev@googlegroups.com
Subject: [PATCH 3/3] kfence: use power-efficient work queue to run delayed work
Date: Mon, 19 Apr 2021 10:50:27 +0200	[thread overview]
Message-ID: <20210419085027.761150-4-elver@google.com> (raw)
In-Reply-To: <20210419085027.761150-1-elver@google.com>

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@google.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 73e7b621fb36..7e20cd9690a2 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -642,7 +642,8 @@ 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);
 
@@ -671,7 +672,7 @@ 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

