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Date:   Sun, 15 Mar 2020 08:18:54 +0000
From:   Wei Yang <richard.weiyang@gmail.com>
To:     "Huang, Ying" <ying.huang@intel.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Dave Hansen <dave.hansen@linux.intel.com>,
        David Hildenbrand <david@redhat.com>,
        Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
        Zi Yan <ziy@nvidia.com>, Michal Hocko <mhocko@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Minchan Kim <minchan@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Hugh Dickins <hughd@google.com>
Subject: Re: [RFC 2/3] mm: Add a new page flag PageLayzyFree() for MADV_FREE
Message-ID: <20200315081854.rcqlmfckeqrh7fbt@master>
Reply-To: Wei Yang <richard.weiyang@gmail.com>
References: <20200228033819.3857058-1-ying.huang@intel.com>
 <20200228033819.3857058-3-ying.huang@intel.com>
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On Fri, Feb 28, 2020 at 11:38:18AM +0800, Huang, Ying wrote:
>From: Huang Ying <ying.huang@intel.com>
>
>Now !PageSwapBacked() is used as the flag for the pages freed lazily
>via MADV_FREE.  This isn't obvious enough.  So Dave suggested to add a
>new page flag for that to improve the code readability.

I am confused with the usage of PageSwapBacked().

Previously I thought this flag means the page is swapin, set in
swapin_readahead(). While I found page_add_new_anon_rmap() would set it too.
This means every anon page would carry this flag. Then what is this flag
means?


-- 
Wei Yang
Help you, Help me