linux-kernel - Re: [PATCH V5 5/6] mm: enable MADV

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Message-ID: <20170227150623.GH26504@dhcp22.suse.cz>
Date:   Mon, 27 Feb 2017 16:06:24 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Shaohua Li <shli@...com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Kernel-team@...com, minchan@...nel.org, hughd@...gle.com,
        hannes@...xchg.org, riel@...hat.com, mgorman@...hsingularity.net,
        akpm@...ux-foundation.org
Subject: Re: [PATCH V5 5/6] mm: enable MADV_FREE for swapless system

On Fri 24-02-17 13:31:48, Shaohua Li wrote:
> Now MADV_FREE pages can be easily reclaimed even for swapless system. We
> can safely enable MADV_FREE for all systems.
> 
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Minchan Kim <minchan@...nel.org>
> Cc: Hugh Dickins <hughd@...gle.com>
> Cc: Rik van Riel <riel@...hat.com>
> Cc: Mel Gorman <mgorman@...hsingularity.net>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Acked-by: Johannes Weiner <hannes@...xchg.org>
> Signed-off-by: Shaohua Li <shli@...com>

Acked-by: Michal Hocko <mhocko@...e.com>

> ---
>  mm/madvise.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 225af7d..5ab4b7b 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -612,13 +612,7 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
>  	case MADV_WILLNEED:
>  		return madvise_willneed(vma, prev, start, end);
>  	case MADV_FREE:
> -		/*
> -		 * XXX: In this implementation, MADV_FREE works like
> -		 * MADV_DONTNEED on swapless system or full swap.
> -		 */
> -		if (get_nr_swap_pages() > 0)
> -			return madvise_free(vma, prev, start, end);
> -		/* passthrough */
> +		return madvise_free(vma, prev, start, end);
>  	case MADV_DONTNEED:
>  		return madvise_dontneed(vma, prev, start, end);
>  	default:
> -- 
> 2.9.3
> 

-- 
Michal Hocko
SUSE Labs