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Date:   Mon, 23 Mar 2020 12:51:11 -0400
From:   Johannes Weiner <hannes@cmpxchg.org>
To:     js1304@gmail.com
Cc:     Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Michal Hocko <mhocko@kernel.org>,
        Hugh Dickins <hughd@google.com>,
        Minchan Kim <minchan@kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Mel Gorman <mgorman@techsingularity.net>, kernel-team@lge.com,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v4 5/8] mm/workingset: handle the page without memcg
Message-ID: <20200323165111.GC204561@cmpxchg.org>
References: <1584942732-2184-1-git-send-email-iamjoonsoo.kim@lge.com>
 <1584942732-2184-6-git-send-email-iamjoonsoo.kim@lge.com>
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On Mon, Mar 23, 2020 at 02:52:09PM +0900, js1304@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> 
> When implementing workingset detection for anonymous page, I found
> some swapcache pages with NULL memcg. They are brought in by swap
> readahead and nobody has touched it.
> 
> The idea behind the workingset code is to tell on page fault time
> whether pages have been previously used or not. Since this page
> hasn't been used, don't store a shadow entry for it; when it later
> faults back in, we treat it as the new page that it is.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>