+ kfence-use-power-efficient-work-queue-to-run-delayed-work.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: kfence: use power-efficient work queue to run delayed work
has been added to the -mm tree.  Its filename is
     kfence-use-power-efficient-work-queue-to-run-delayed-work.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/kfence-use-power-efficient-work-queue-to-run-delayed-work.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/kfence-use-power-efficient-work-queue-to-run-delayed-work.patch

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------------------------------------------------------
From: Marco Elver <elver@google.com>
Subject: 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 (https://lwn.net/Articles/731052/).

Link: https://lkml.kernel.org/r/20210419085027.761150-4-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Hillf Danton <hdanton@sina.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kfence/core.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/mm/kfence/core.c~kfence-use-power-efficient-work-queue-to-run-delayed-work
+++ a/mm/kfence/core.c
@@ -642,7 +642,8 @@ static void toggle_allocation_gate(struc
 	/* 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));
_

Patches currently in -mm which might be from elver@google.com are

kfence-zero-guard-page-after-out-of-bounds-access.patch
kfence-await-for-allocation-using-wait_event.patch
kfence-maximize-allocation-wait-timeout-duration.patch
kfence-use-power-efficient-work-queue-to-run-delayed-work.patch