linux-kernel - Re: [PATCH 1/3] page-allocator: Allow too high-order warning messages to be suppressed with __GFP

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Date:	Thu, 16 Jul 2009 10:02:53 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Mel Gorman <mel@....ul.ie>
Cc:	kosaki.motohiro@...fujitsu.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Linux Memory Management List <linux-mm@...ck.org>,
	Heinz Diehl <htd@...cy-poultry.org>,
	David Miller <davem@...emloft.net>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 1/3] page-allocator: Allow too high-order warning messages to be suppressed with __GFP_NOWARN

> The page allocator warns once when an order >= MAX_ORDER is specified.
> This is to catch callers of the allocator that are always falling back
> to their worst-case when it was not expected. However, there are cases
> where the caller is behaving correctly but cannot suppress the warning.
> This patch allows the warning to be suppressed by the callers by
> specifying __GFP_NOWARN.
> 
> Signed-off-by: Mel Gorman <mel@....ul.ie>
> ---
>  mm/page_alloc.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index caa9268..b469a05 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1740,8 +1740,10 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>  	 * be using allocators in order of preference for an area that is
>  	 * too large.
>  	 */
> -	if (WARN_ON_ONCE(order >= MAX_ORDER))
> +	if (order >= MAX_ORDER) {
> +		WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));
>  		return NULL;
> +	}

Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>


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