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/20210421105132.3965998-4-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 9742649..e18fbbd 100644 (file)
--- 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));