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Date: Thu, 5 Apr 2018 15:11:23 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Roman Gushchin <guro@fb.com>, linux-mm@kvack.org, Michal Hocko
 <mhocko@suse.com>, Johannes Weiner <hannes@cmpxchg.org>,
 linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
 kernel-team@fb.com
Subject: Re: [PATCH 3/3] dcache: account external names as indirectly
 reclaimable memory
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On Tue, 13 Mar 2018 00:45:32 +0000 Al Viro <viro@ZenIV.linux.org.uk> wrote:

> 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.

So.. where are we at with this issue?