linux-kernel - Re: [v6 04/15] mm: discard memblock data later

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Date:   Fri, 11 Aug 2017 15:00:47 -0400
From:   Pasha Tatashin <pasha.tatashin@...cle.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-kernel@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        x86@...nel.org, kasan-dev@...glegroups.com, borntraeger@...ibm.com,
        heiko.carstens@...ibm.com, davem@...emloft.net,
        willy@...radead.org, ard.biesheuvel@...aro.org,
        will.deacon@....com, catalin.marinas@....com, sam@...nborg.org,
        Mel Gorman <mgorman@...e.de>
Subject: Re: [v6 04/15] mm: discard memblock data later

Hi Michal,

This suggestion won't work, because there are arches without memblock 
support: tile, sh...

So, I would still need to have:

#ifdef CONFIG_MEMBLOCK in page_alloc, or define memblock_discard() stubs 
in nobootmem headfile. In either case it would become messier than what 
it is right now.

Pasha

> I have just one nit below
> Acked-by: Michal Hocko <mhocko@...e.com>
> 
> [...]
>> diff --git a/mm/memblock.c b/mm/memblock.c
>> index 2cb25fe4452c..bf14aea6ab70 100644
>> --- a/mm/memblock.c
>> +++ b/mm/memblock.c
>> @@ -285,31 +285,27 @@ static void __init_memblock memblock_remove_region(struct memblock_type *type, u
>>   }
>>   
>>   #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
> 
> pull this ifdef inside memblock_discard and you do not have an another
> one in page_alloc_init_late
> 
> [...]
>> +/**
>> + * Discard memory and reserved arrays if they were allocated
>> + */
>> +void __init memblock_discard(void)
>>   {
> 
> here
> 
>> -	if (memblock.memory.regions == memblock_memory_init_regions)
>> -		return 0;
>> +	phys_addr_t addr, size;
>>   
>> -	*addr = __pa(memblock.memory.regions);
>> +	if (memblock.reserved.regions != memblock_reserved_init_regions) {
>> +		addr = __pa(memblock.reserved.regions);
>> +		size = PAGE_ALIGN(sizeof(struct memblock_region) *
>> +				  memblock.reserved.max);
>> +		__memblock_free_late(addr, size);
>> +	}
>>   
>> -	return PAGE_ALIGN(sizeof(struct memblock_region) *
>> -			  memblock.memory.max);
>> +	if (memblock.memory.regions == memblock_memory_init_regions) {
>> +		addr = __pa(memblock.memory.regions);
>> +		size = PAGE_ALIGN(sizeof(struct memblock_region) *
>> +				  memblock.memory.max);
>> +		__memblock_free_late(addr, size);
>> +	}
>>   }
>> -
>>   #endif