linux-kernel - Re: [PATCH v8 34/46] x86, mm: Add check before clear pte above max_low

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Message-ID: <CAE9FiQVN1-W3vLK5J75kQgt+0BW3sd2GkWi+4EeJMYwoyPi-gg@mail.gmail.com>
Date:	Wed, 28 Nov 2012 12:38:06 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>, Jacob Shin <jacob.shin@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 34/46] x86, mm: Add check before clear pte above
 max_low_pfn on 32bit

On Wed, Nov 28, 2012 at 11:09 AM, Konrad Rzeszutek Wilk
<konrad.wilk@...cle.com> wrote:
>>       /*
>>        * Remove any mappings which extend past the end of physical
>> -      * memory from the boot time page table:
>> +      * memory from the boot time page table.
>> +      * In virtual address space, we should have at least two pages
>> +      * from VMALLOC_END to pkmap or fixmap according to VMALLOC_END
>> +      * definition. And max_low_pfn is set to VMALLOC_END physical
>> +      * address. If initial memory mapping is doing right job, we
>> +      * should have pte used near max_low_pfn or one pmd is not present.
>
> 'have pte used near' ?
>
> Do you mean we should have an used PTE near max_low_pfn and one
> empty PMD?
>

==>
         * we should have used PTE to map address near max_low_pfn or
         * one empty PMD
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