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SubjectRe: [PATCH] mm/memory hotplug: print the last vmemmap region at the end of hot add memory

On 06/09/2015 07:30 AM, Andrew Morton wrote:
> On Mon, 8 Jun 2015 14:44:41 +0800 Zhu Guihua <zhugh.fnst@cn.fujitsu.com> wrote:
>
>> When hot add two nodes continuously, we found the vmemmap region info is a
>> bit messed. The last region of node 2 is printed when node 3 hot added,
>> like the following:
>> Initmem setup node 2 [mem 0x0000000000000000-0xffffffffffffffff]
>> On node 2 totalpages: 0
>> Built 2 zonelists in Node order, mobility grouping on. Total pages: 16090539
>> Policy zone: Normal
>> init_memory_mapping: [mem 0x40000000000-0x407ffffffff]
>> [mem 0x40000000000-0x407ffffffff] page 1G
>> [ffffea1000000000-ffffea10001fffff] PMD -> [ffff8a077d800000-ffff8a077d9fffff] on node 2
>> [ffffea1000200000-ffffea10003fffff] PMD -> [ffff8a077de00000-ffff8a077dffffff] on node 2
>> ...
>> [ffffea101f600000-ffffea101f9fffff] PMD -> [ffff8a074ac00000-ffff8a074affffff] on node 2
>> [ffffea101fa00000-ffffea101fdfffff] PMD -> [ffff8a074a800000-ffff8a074abfffff] on node 2
>> Initmem setup node 3 [mem 0x0000000000000000-0xffffffffffffffff]
>> On node 3 totalpages: 0
>> Built 3 zonelists in Node order, mobility grouping on. Total pages: 16090539
>> Policy zone: Normal
>> init_memory_mapping: [mem 0x60000000000-0x607ffffffff]
>> [mem 0x60000000000-0x607ffffffff] page 1G
>> [ffffea101fe00000-ffffea101fffffff] PMD -> [ffff8a074a400000-ffff8a074a5fffff] on node 2 <=== node 2 ???
>> [ffffea1800000000-ffffea18001fffff] PMD -> [ffff8a074a600000-ffff8a074a7fffff] on node 3
>> [ffffea1800200000-ffffea18005fffff] PMD -> [ffff8a074a000000-ffff8a074a3fffff] on node 3
>> [ffffea1800600000-ffffea18009fffff] PMD -> [ffff8a0749c00000-ffff8a0749ffffff] on node 3
>> ...
>>
>> The cause is the last region was missed at the and of hot add memory, and
>> p_start, p_end, node_start were not reset, so when hot add memory to a new
>> node, it will consider they are not contiguous blocks and print the
>> previous one. So we print the last vmemmap region at the end of hot add
>> memory to avoid the confusion.
>>
>> ...
>>
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -513,6 +513,7 @@ int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
>> break;
>> err = 0;
>> }
>> + vmemmap_populate_print_last();
>>
>> return err;
>> }
> vmemmap_populate_print_last() is only available on x86_64, when
> CONFIG_SPARSEMEM_VMEMMAP=y. Are you sure this won't break builds?

I tried this on i386 and on x86_64 when CONFIG_SPARSEMEM_VMEMMAP=n ,
it builds ok.

Thanks,
Zhu

>
> .
>



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