Re: [PATCH 3/3] dcache: account external names as indirectly reclaimable memory

[Al Viro <viro@ZenIV.linux.org.uk>]

On Mon, Mar 12, 2018 at 10:36:38PM +0000, Roman Gushchin wrote:

> Ah, I see...
> 
> I think, it's better to account them when we're actually freeing,
> otherwise we will have strange path:
> (indirectly) reclaimable -> unreclaimable -> free
> 
> Do you agree?

> +static void __d_free_external_name(struct rcu_head *head)
> +{
> +	struct external_name *name;
> +
> +	name = container_of(head, struct external_name, u.head);
> +
> +	mod_node_page_state(page_pgdat(virt_to_page(name)),
> +			    NR_INDIRECTLY_RECLAIMABLE_BYTES,
> +			    -ksize(name));
> +
> +	kfree(name);
> +}

Maybe, but then you want to call that from __d_free_external() and from
failure path in __d_alloc() as well.  Duplicating something that convoluted
and easy to get out of sync is just asking for trouble.