On Tue, Jun 14, 2022 at 06:03:59PM -0400, Waiman Long wrote:
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index 7dd64139a7c7..abba063ae5ee 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -1417,12 +1417,16 @@ static void kmemleak_scan(void)
> struct zone *zone;
> int __maybe_unused i;
> int new_leaks = 0;
> + int loop1_cnt = 0;
>
> jiffies_last_scan = jiffies;
>
> /* prepare the kmemleak_object's */
> rcu_read_lock();
> list_for_each_entry_rcu(object, &object_list, object_list) {
> + bool obj_pinned = false;
> +
> + loop1_cnt++;
> raw_spin_lock_irq(&object->lock);
> #ifdef DEBUG
> /*
> @@ -1437,10 +1441,32 @@ static void kmemleak_scan(void)
> #endif
> /* reset the reference count (whiten the object) */
> object->count = 0;
> - if (color_gray(object) && get_object(object))
> + if (color_gray(object) && get_object(object)) {
> list_add_tail(&object->gray_list, &gray_list);
> + obj_pinned = true;
> + }
>
> raw_spin_unlock_irq(&object->lock);
> +
> + /*
> + * Do a cond_resched() to avoid soft lockup every 64k objects.
> + * Make sure a reference has been taken so that the object
> + * won't go away without RCU read lock.
> + */
> + if (!(loop1_cnt & 0xffff)) {
> + if (!obj_pinned && !get_object(object)) {
> + /* Try the next object instead */
> + loop1_cnt--;
> + continue;
> + }
With this trick we could probably get rid of rcu_read_lock() and take
the kmemleak_lock instead. But that's for another patch.
> +
> + rcu_read_unlock();
> + cond_resched();
> + rcu_read_lock();
cond_resched_rcu() to save a couple of lines?
> +
> + if (!obj_pinned)
> + put_object(object);
> + }
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Thanks.
