linux-kernel - Re: [PATCH v2] mm: exclude isolated non-lru pages from NR_ISOLATED_ANON or NR_ISOLATED

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Message-ID: <20161014135334.GF6063@dhcp22.suse.cz>
Date:   Fri, 14 Oct 2016 15:53:34 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Ming Ling <ming.ling@...eadtrum.com>, akpm@...ux-foundation.org,
        mgorman@...hsingularity.net, vbabka@...e.cz, hannes@...xchg.org,
        baiyaowei@...s.chinamobile.com, iamjoonsoo.kim@....com,
        rientjes@...gle.com, hughd@...gle.com,
        kirill.shutemov@...ux.intel.com, riel@...hat.com, mgorman@...e.de,
        aquini@...hat.com, corbet@....net, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, orson.zhai@...eadtrum.com,
        geng.ren@...eadtrum.com, chunyan.zhang@...eadtrum.com,
        zhizhou.tian@...eadtrum.com, yuming.han@...eadtrum.com,
        xiajing@...eadst.com
Subject: Re: [PATCH v2] mm: exclude isolated non-lru pages from
 NR_ISOLATED_ANON or NR_ISOLATED_FILE.

On Fri 14-10-16 22:46:04, Minchan Kim wrote:
[...]
> > > > Why don't you simply mimic what shrink_inactive_list does? Aka count the
> > > > number of isolated pages and then account them when appropriate?
> > > >
> > > I think i am correcting clearly wrong part. So, there is no need to
> > > describe it too detailed. It's a misunderstanding, and i will add
> > > more comments as you suggest.
> > 
> > OK, so could you explain why you prefer to relyon __PageMovable rather
> > than do a trivial counting during the isolation?
> 
> I don't get it. Could you elaborate it a bit more?

It is really simple. You can count the number of file and anonymous
pages while they are isolated and then account them to NR_ISOLATED_*
later. Basically the same thing we do during the reclaim. We absolutely
do not have to rely on __PageMovable and make this code more complex
than necessary.
-- 
Michal Hocko
SUSE Labs