linux-kernel - Re: [PATCH 2/2] mm/cma_debug: correct size input to bitmap function

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Date:	Wed, 15 Jul 2015 14:03:32 +0200
From:	Michal Nazarewicz <mina86@...a86.com>
To:	Joonsoo Kim <js1304@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Sasha Levin <sasha.levin@...cle.com>,
	Stefan Strogin <stefan.strogin@...il.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH 2/2] mm/cma_debug: correct size input to bitmap function

On Wed, Jul 15 2015, Joonsoo Kim wrote:
> In CMA, 1 bit in bitmap means 1 << order_per_bits pages so
> size of bitmap is cma->count >> order_per_bits rather than
> just cma->count. This patch fixes it.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>

Acked-by: Michal Nazarewicz <mina86@...a86.com>

> ---
>  mm/cma_debug.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/mm/cma_debug.c b/mm/cma_debug.c
> index 22190a7..f8e4b60 100644
> --- a/mm/cma_debug.c
> +++ b/mm/cma_debug.c
> @@ -39,7 +39,7 @@ static int cma_used_get(void *data, u64 *val)
>  
>  	mutex_lock(&cma->lock);
>  	/* pages counter is smaller than sizeof(int) */
> -	used = bitmap_weight(cma->bitmap, (int)cma->count);
> +	used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma));
>  	mutex_unlock(&cma->lock);
>  	*val = (u64)used << cma->order_per_bit;
>  
> @@ -52,13 +52,14 @@ static int cma_maxchunk_get(void *data, u64 *val)
>  	struct cma *cma = data;
>  	unsigned long maxchunk = 0;
>  	unsigned long start, end = 0;
> +	unsigned long bitmap_maxno = cma_bitmap_maxno(cma);
>  
>  	mutex_lock(&cma->lock);
>  	for (;;) {
> -		start = find_next_zero_bit(cma->bitmap, cma->count, end);
> +		start = find_next_zero_bit(cma->bitmap, bitmap_maxno, end);
>  		if (start >= cma->count)
>  			break;
> -		end = find_next_bit(cma->bitmap, cma->count, start);
> +		end = find_next_bit(cma->bitmap, bitmap_maxno, start);
>  		maxchunk = max(end - start, maxchunk);
>  	}
>  	mutex_unlock(&cma->lock);
> -- 
> 1.9.1
>

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
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