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Date:   Wed, 15 Apr 2020 14:44:26 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     Andrea Arcangeli <aarcange@redhat.com>, Zi Yan <ziy@nvidia.com>,
        Yang Shi <yang.shi@linux.alibaba.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        John Hubbard <jhubbard@nvidia.com>,
        William Kucharski <william.kucharski@oracle.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv3, RESEND 6/8] khugepaged: Allow to collapse PTE-mapped
 compound pages
Message-Id: <20200415144426.a146ef173140f5bc396a6dcd@linux-foundation.org>
In-Reply-To: <20200413125220.663-7-kirill.shutemov@linux.intel.com>
References: <20200413125220.663-1-kirill.shutemov@linux.intel.com>
        <20200413125220.663-7-kirill.shutemov@linux.intel.com>
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On Mon, 13 Apr 2020 15:52:18 +0300 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> wrote:

> We can collapse PTE-mapped compound pages. We only need to avoid
> handling them more than once: lock/unlock page only once if it's present
> in the PMD range multiple times as it handled on compound level. The
> same goes for LRU isolation and putback.
> 
> ...
>
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -515,17 +515,30 @@ void __khugepaged_exit(struct mm_struct *mm)
>  
>  static void release_pte_page(struct page *page)
>  {
> -	dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page));

I have

	dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_lru(page));

here.  Is there some prerequisite which I wasn't able to find?