Re: [PATCH v6 01/13] mm/demotion: Add support for explicit memory tiers

[Davidlohr Bueso]

> > memory_tier_lock isn't held to call register_memory_tier() in this
> > patch.  That will cause confusion.
>
> will this help to explain this better
> modified   mm/memory-tiers.c
> @@ -151,6 +151,11 @@ static void insert_memory_tier(struct memory_tier *memtier)
> 	struct list_head *ent;
> 	struct memory_tier *tmp_memtier;
>
> +	if (IS_ENABLED(CONFIG_DEBUG_VM) && !mutex_is_locked(&memory_tier_lock)) {
> +		WARN_ON_ONCE(1);
> +		return;
> +	}

Why not just use lockdep here instead?