Re: [Patch 8/8] kexec: allow to shrink reserved memory

[Amerigo Wang <amwang@redhat.com>]

KAMEZAWA Hiroyuki wrote:
> On Wed, 19 Aug 2009 10:41:13 +0800
> Amerigo Wang <amwang@redhat.com> wrote:
>
>   
>> KAMEZAWA Hiroyuki wrote:
>>     
>>> On Tue, 18 Aug 2009 18:35:32 +0800
>>> Amerigo Wang <amwang@redhat.com> wrote:
>>>
>>>   
>>>       
>>>> KAMEZAWA Hiroyuki wrote:
>>>>     
>>>>         
>>>>> On Tue, 18 Aug 2009 14:31:23 +0800
>>>>> Amerigo Wang <amwang@redhat.com> wrote:
>>>>>   
>>>>>       
>>>>>           
>>>>>>>     It's hidden from the system before mem_init() ?
>>>>>>>   
>>>>>>>       
>>>>>>>           
>>>>>>>               
>>>>>> Not sure, but probably yes. It is reserved in setup_arch() which is 
>>>>>> before mm_init() which calls mem_init().
>>>>>>
>>>>>> Do you have any advice to free that reserved memory after boot? :)
>>>>>>
>>>>>>     
>>>>>>         
>>>>>>             
>>>>> Let's see arch/x86/mm/init.c::free_initmem()
>>>>>
>>>>> Maybe it's all you want.
>>>>>
>>>>> 	- ClearPageReserved()
>>>>> 	- init_page_count()
>>>>> 	- free_page()
>>>>> 	- totalram_pages++
>>>>>   
>>>>>       
>>>>>           
>>>> Just FYI: calling ClearPageReserved() caused an oops: "Unable to handle 
>>>> paging request".
>>>>
>>>> I am trying to figure out why...
>>>>
>>>>     
>>>>         
>>> Hmm...then....memmap is not there.
>>> pfn_valid() check will help you. What arch ? x86-64 ?
>>>   
>>>       
>> Hmm, yes, x86_64, but this code is arch-independent, I mean it should 
>> work or not work on all arch, no?
>>
>> So I am afraid we need to use other API to free it...
>>
>>     
> The, problem is whether memmap is there or not. That's all.
> plz see init sequence and check there are memmap.
> If memory-for-crash is obtained via bootmem,
> Don't you try to free memory hole ?
>   

Yes, I am checking the code. Thanks!