linux-kernel - Re: [PATCH 4/5] mm/memcontrol: allow to uncharge page without using page->lru field

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Message-ID: <20170710165420.GC4964@redhat.com>
Date:   Mon, 10 Jul 2017 12:54:21 -0400
From:   Jerome Glisse <jglisse@...hat.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        John Hubbard <jhubbard@...dia.com>,
        David Nellans <dnellans@...dia.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Balbir Singh <bsingharora@...il.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        cgroups@...r.kernel.org
Subject: Re: [PATCH 4/5] mm/memcontrol: allow to uncharge page without using
 page->lru field

On Mon, Jul 10, 2017 at 06:36:52PM +0200, Michal Hocko wrote:
> On Mon 10-07-17 12:25:42, Jerome Glisse wrote:
> [...]
> > Bottom line is that we can always free and uncharge device memory
> > page just like any regular page.
> 
> OK, this answers my earlier question. Then it should be feasible to
> charge this memory. There are still some things to handle. E.g. how do
> we consider this memory during oom victim selection (this is not
> accounted as an anonymous memory in get_mm_counter, right?), maybe others.
> But the primary point is that nobody pins the memory outside of the
> mapping.

At this point it is accounted as a regular page would be (anonymous, file
or share memory). I wanted mm_counters to reflect memcg but i can untie
that. Like i said at this point we are unsure how usage of such memory
will impact thing so i wanted to keep all thing as if it was regular
memory to avoid anuything to behave too much differently.

Jérôme