Re: [PATCH x86,mm] fix pgt_buf_end when memory hotplug

Lai Jiangshan
2011-09-21T05:49:49Z

On 09/08/2011 11:21 PM, Stefano Stabellini wrote:
> On Thu, 8 Sep 2011, Lai Jiangshan wrote:
>>
>> When I test memory hotplug, such message is always outputted when hot-adding
>> a memory block:
>>
>> initial kernel pagetable allocation wasted ffffffffffffffff pages
>
> I take you are using tip/x86/mm, because that is the only branch that
> contains that warning.

No,
I was using tip/master.

Thanks,
Lai

>
>
>> This message comes from init_memory_mapping(), it shows "pgt_buf_end" is
>> incorrect here, and I found it was caused by alloc_low_page().
>>
>> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
>> ---
>> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
>> index bbaaa00..e138e0a 100644
>> --- a/arch/x86/mm/init_64.c
>> +++ b/arch/x86/mm/init_64.c
>> @@ -317,7 +317,7 @@ void __init cleanup_highmap(void)
>>
>> static __ref void *alloc_low_page(unsigned long *phys)
>> {
>> - unsigned long pfn = pgt_buf_end++;
>> + unsigned long pfn;
>> void *adr;
>>
>> if (after_bootmem) {
>> @@ -327,6 +327,7 @@ static __ref void *alloc_low_page(unsigned long *phys)
>> return adr;
>> }
>>
>> + pfn = pgt_buf_end++;
>> if (pfn >= pgt_buf_top)
>> panic("alloc_low_page: ran out of memory");
>
>
> This patch makes sense to me. It would also make sense to print the
> "allocation wasted" warning only if (!after_bootmem).
> --
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