linux-kernel - Re: [PATCH v5 08/14] memory-hotplug: Common APIs to support page tables hot-remove

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Message-ID: <50DA65B7.2050707@cn.fujitsu.com>
Date:	Wed, 26 Dec 2012 10:49:27 +0800
From:	Tang Chen <tangchen@...fujitsu.com>
To:	Jianguo Wu <wujianguo@...wei.com>
CC:	akpm@...ux-foundation.org, rientjes@...gle.com, liuj97@...il.com,
	len.brown@...el.com, benh@...nel.crashing.org, paulus@...ba.org,
	cl@...ux.com, minchan.kim@...il.com,
	kosaki.motohiro@...fujitsu.com, isimatu.yasuaki@...fujitsu.com,
	wency@...fujitsu.com, hpa@...or.com, linfeng@...fujitsu.com,
	laijs@...fujitsu.com, mgorman@...e.de, yinghai@...nel.org,
	x86@...nel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-acpi@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
	linux-ia64@...r.kernel.org, cmetcalf@...era.com,
	sparclinux@...r.kernel.org
Subject: Re: [PATCH v5 08/14] memory-hotplug: Common APIs to support page
 tables hot-remove

On 12/25/2012 04:17 PM, Jianguo Wu wrote:
>> +
>> +static void __meminit free_pagetable(struct page *page, int order)
>> +{
>> +	struct zone *zone;
>> +	bool bootmem = false;
>> +	unsigned long magic;
>> +
>> +	/* bootmem page has reserved flag */
>> +	if (PageReserved(page)) {
>> +		__ClearPageReserved(page);
>> +		bootmem = true;
>> +
>> +		magic = (unsigned long)page->lru.next;
>> +		if (magic == SECTION_INFO || magic == MIX_SECTION_INFO)
>> +			put_page_bootmem(page);
>
> Hi Tang,
>
> For removing memmap of sparse-vmemmap, in cpu_has_pse case, if magic == SECTION_INFO,
> the order will be get_order(PMD_SIZE), so we need a loop here to put all the 512 pages.
>
Hi Wu,

Thanks for reminding me that. I truely missed it.

And since in register_page_bootmem_info_section(), a whole memory
section will be set as SECTION_INFO, I think we don't need to check
the page magic one by one, just the first one is enough. :)

I will fix it, thanks. :)

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