linux-kernel - Re: [Bug fix PATCH v4] Reusing a resource structure allocated by bootmem

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Message-ID: <20130418134206.GB21444@cmpxchg.org>
Date:	Thu, 18 Apr 2013 06:42:06 -0700
From:	Johannes Weiner <hannes@...xchg.org>
To:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc:	akpm@...ux-foundation.org, toshi.kani@...com, linuxram@...ibm.com,
	rientjes@...gle.com, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [Bug fix PATCH v4] Reusing a resource structure allocated by
 bootmem

On Thu, Apr 18, 2013 at 05:36:12PM +0900, Yasuaki Ishimatsu wrote:
> @@ -151,6 +162,39 @@ __initcall(ioresources_init);
>  
>  #endif /* CONFIG_PROC_FS */
>  
> +static void free_resource(struct resource *res)
> +{
> +	if (!res)
> +		return;
> +
> +	if (PageSlab(virt_to_head_page(res))) {
> +		spin_lock(&bootmem_resource_lock);
> +		res->sibling = bootmem_resource.sibling;
> +		bootmem_resource.sibling = res;
> +		spin_unlock(&bootmem_resource_lock);
> +	} else {
> +		kfree(res);
> +	}

The branch is mixed up, you are collecting slab objects in
bootmem_resource and kfreeing bootmem.

> +static struct resource *get_resource(gfp_t flags)
> +{
> +	struct resource *res = NULL;
> +
> +	spin_lock(&bootmem_resource_lock);
> +	if (bootmem_resource.sibling) {
> +		res = bootmem_resource.sibling;
> +		bootmem_resource.sibling = res->sibling;
> +		memset(res, 0, sizeof(struct resource));
> +	}
> +	spin_unlock(&bootmem_resource_lock);
> +
> +	if (!res)
> +		res = kzalloc(sizeof(struct resource), flags);
> +
> +	return res;
> +}
> +
>  /* Return the conflict entry if you can't request it */
>  static struct resource * __request_resource(struct resource *root, struct resource *new)
>  {
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