Re: [PATCH v3 2/5] memblock: Improve memblock to support allocation from lower address.

[Zhang Yanfei <zhangyanfei@cn.fujitsu.com>]

Hello tejun,

On 09/24/2013 04:21 AM, Tejun Heo wrote:
> Hello,
> 
> On Tue, Sep 24, 2013 at 02:07:13AM +0800, Zhang Yanfei wrote:
>> Yes, I am following your advice in principle but kind of confused by
>> something you said above. Where should the set_memblock_alloc_above_kernel
>> be used? IMO, the function is like:
>>
>> find_in_range_node()
>> {
>>      if (ok) {
>>            /* bottom-up */
>>            ret = __memblock_find_in_range(max(start, _end_of_kernel), end...);
>>            if (!ret)
>>                  return ret;
>>      }
>>
>>      /* top-down retry */
>>      return __memblock_find_in_range_rev(start, end...)
>> }
>>
>> For bottom-up allocation, we always start from max(start, _end_of_kernel).
> 
> Oh, I was talking about naming of the memblock_set_bottom_up()
> function.  We aren't really doing pure bottom up allocations, so I
> think it probably would be clearer if the name clearly denotes that
> we're doing above-kernel allocation.

I see. But I think memblock_set_alloc_above_kernel may lose the info
that we are doing bottom-up allocation. So my idea is we introduce
pure bottom-up allocation mode in previous patches and we use the
bottom-up allocation here and limit the start address above the kernel
, with explicit comments to indicate this.

How do you think?

Thanks.

> 
> Thanks.
> 


-- 
Thanks.
Zhang Yanfei