linux-kernel - Re: mm/zsmalloc.c: count in handle's size when calculating pages_per

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Date:	Fri, 20 Mar 2015 14:55:59 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Yinghao Xie <yinghao.xie@...sung.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Minchan Kim <minchan@...nel.org>,
	Nitin Gupta <ngupta@...are.org>, mm <linux-mm@...ck.org>,
	lkml <linux-kernel@...r.kernel.org>, sergey.senozhatsky@...il.com
Subject: Re: mm/zsmalloc.c: count in handle's size when calculating
 pages_per_zspage


Hello,

sorry, I've a question.

On (03/19/15 11:39), Yinghao Xie wrote:
> @@ -1426,11 +1430,6 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size)
>  	/* extra space in chunk to keep the handle */
>  	size += ZS_HANDLE_SIZE;
>  	class = pool->size_class[get_size_class_index(size)];
> -	/* In huge class size, we store the handle into first_page->private */
> -	if (class->huge) {
> -		size -= ZS_HANDLE_SIZE;
> -		class = pool->size_class[get_size_class_index(size)];
> -	}

if huge class uses page->private to store a handle, shouldn't we pass
"size -= ZS_HANDLE_SIZE" to get_size_class_index() ?

	-ss

>  	spin_lock(&class->lock);
>  	first_page = find_get_zspage(class);
> @@ -1856,9 +1855,7 @@ struct zs_pool *zs_create_pool(char *name, gfp_t flags)
>  		struct size_class *class;
>  
>  		size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
> -		if (size > ZS_MAX_ALLOC_SIZE)
> -			size = ZS_MAX_ALLOC_SIZE;
> -		pages_per_zspage = get_pages_per_zspage(size);
> +		pages_per_zspage = get_pages_per_zspage(size + ZS_HANDLE_SIZE);
>  
>  		/*
>  		 * size_class is used for normal zsmalloc operation such
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