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

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Message-ID: <51708000.4060106@jp.fujitsu.com>
Date:	Fri, 19 Apr 2013 08:21:36 +0900
From:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To:	Johannes Weiner <hannes@...xchg.org>
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

2013/04/18 22:42, Johannes Weiner wrote:
> 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.

Ah. I'm wrong. I'll update soon.

Thanks,
Yasuaki Ishimatsu

>
>> +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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