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Date: Fri, 15 Dec 2017 13:01:51 +0300
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Nitin Gupta <nitin.m.gupta@oracle.com>
Cc: linux-mm@kvack.org, steven.sistare@oracle.com,
        Andrew Morton <akpm@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>, Mel Gorman <mgorman@suse.de>,
        Nadav Amit <namit@vmware.com>, Minchan Kim <minchan@kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Vegard Nossum <vegard.nossum@oracle.com>,
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Subject: Re: [PATCH] mm: Reduce memory bloat with THP
Message-ID: <20171215100151.b7j66q7sg2wsrex3@node.shutemov.name>
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On Thu, Dec 14, 2017 at 05:28:52PM -0800, Nitin Gupta wrote:
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 751e97a..b2ec07b 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -508,6 +508,7 @@ static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
>  					unsigned long start, unsigned long end)
>  {
>  	zap_page_range(vma, start, end - start);
> +	vma->space_efficient = true;
>  	return 0;
>  }
>  

And this modifies vma without down_write(mmap_sem).

No.

-- 
 Kirill A. Shutemov