Re: mm: BUG in do_huge_pmd_wp_page

[Simon Jeons <simon.jeons@gmail.com>]

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Hi Peter,
On 04/25/2013 06:51 AM, H. Peter Anvin wrote:
> On 04/10/2013 01:02 AM, Minchan Kim wrote:
>> When I am looking at the code, I was wonder about the logic of GHZP(aka,
>> get_huge_zero_page) reference handling. The logic depends on that page
>> allocator never alocate PFN 0.
>>
>> Who makes sure it? What happens if allocator allocates PFN 0?
>> I don't know all of architecture makes sure it.
>> You investigated it for all arches?
>>
> This isn't manifest, right?  At least on x86 we should never, ever
> allocate PFN 0.

I see in memblock_trim_memory(): start = round_up(orig_start, align); 
here align is PAGE_SIZE, so the dump of zone ranges in my machine is [  
   0.000000]  DMA      [mem 0x00001000-0x00ffffff]. Why PFN 0 is not 
used? just for align?

>
> 	-hpa
>
>
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