linux-kernel - Re: [PATCH] block: partition: optimize memory allocation in check

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Message-ID: <1359688835.15911.4.camel@joe-AO722>
Date:	Thu, 31 Jan 2013 19:20:35 -0800
From:	Joe Perches <joe@...ches.com>
To:	Ming Lei <ming.lei@...onical.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
	Felipe Balbi <balbi@...com>, stable@...r.kernel.org
Subject: Re: [PATCH] block: partition: optimize memory allocation in
 check_partition

On Fri, 2013-02-01 at 11:07 +0800, Ming Lei wrote:
> Currently, sizeof(struct parsed_partitions) may be 64KB in 32bit arch,
> so it is easy to trigger page allocation failure by check_partition,
[]
> This patch does below optimizations on the allocation of struct
> parsed_partitions to try to address the issue:
> 
> - make parsed_partitions.parts as pointer so that the pointed memory
> can fit in 32KB buffer, then approximate 32KB memory can be saved
> 
> - vmalloc the buffer pointed by parsed_partitions.parts because
> 32KB is still a bit big for kmalloc
[]
> diff --git a/block/partitions/check.h b/block/partitions/check.h
[]
> @@ -15,13 +15,15 @@ struct parsed_partitions {
>  		int flags;
>  		bool has_info;
>  		struct partition_meta_info info;
> -	} parts[DISK_MAX_PARTS];
> +	} *parts;

This is relatively unusual style.
Could you break out this struct instead?

struct partition_parts {
	...
};

and use

	struct partition_parts *parts;

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