Re: [PATCH V4] mm: memory hot-add: memory can not be added to movable zone defaultly

[Changsheng Liu <liuchangsheng@inspur.com>]

On 9/1/2015 23:37, Yasuaki Ishimatsu wrote:
> On Mon, 31 Aug 2015 01:58:40 -0400
> Changsheng Liu <liuchangsheng@inspur.com> wrote:
>
>> From: Changsheng Liu <liuchangcheng@inspur.com>
>>
>> After the user config CONFIG_MOVABLE_NODE and movable_node kernel option,
>> When the memory is hot added, should_add_memory_movable() return 0
>> because all zones including movable zone are empty,
>> so the memory that was hot added will be added  to the normal zone
>> and the normal zone will be created firstly.
>> But we want the whole node to be added to movable zone defaultly.
>>
>> So we change should_add_memory_movable(): if the user config
>> CONFIG_MOVABLE_NODE and movable_node kernel option
>> it will always return 1 and all zones is empty at the same time,
>> so that the movable zone will be created firstly
>> and then the whole node will be added to movable zone defaultly.
>> If we want the node to be added to normal zone,
>> we can do it as follows:
>> "echo online_kernel > /sys/devices/system/memory/memoryXXX/state"
>>
>> If the memory is added to movable zone defaultly,
>> the user can offline it and add it to other zone again.
>> But if the memory is added to normal zone defaultly,
>> the user will not offline the memory used by kernel.
>>
>> Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
>> Reviewed-by: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
>> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
>> Reviewed-by: Xiaofeng Yan <yanxiaofeng@inspur.com>
>> Signed-off-by: Changsheng Liu <liuchangcheng@inspur.com>
>> Tested-by: Dongdong Fan <fandd@inspur.com>
>> ---
>>   mm/memory_hotplug.c |    5 +++++
>>   1 files changed, 5 insertions(+), 0 deletions(-)
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 26fbba7..d1149ff 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1197,6 +1197,11 @@ static int should_add_memory_movable(int nid, u64 start, u64 size)
>>   	unsigned long start_pfn = start >> PAGE_SHIFT;
>>   	pg_data_t *pgdat = NODE_DATA(nid);
>>   	struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE;
>> +	struct zone *normal_zone = pgdat->node_zones + ZONE_NORMAL;
>> +
>> +	if (movable_node_is_enabled()
>> +	&& (zone_end_pfn(normal_zone) <= start_pfn))
>> +		return 1;
> If system boots up without movable_node, kernel behavior is changed by the patch.
> And you syould consider other zone.
>
> How about it. The patch is no build and test.
     Thanks for your suggestion. We will test the patch on our platform
>
>
> ---
>   mm/memory_hotplug.c |   36 ++++++++++++++++++++++++++++++++----
>   1 files changed, 32 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 6da82bc..321595d 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1198,6 +1198,8 @@ static int check_hotplug_memory_range(u64 start, u64 size)
>   /*
>    * If movable zone has already been setup, newly added memory should be check.
>    * If its address is higher than movable zone, it should be added as movable.
> + * And if system boots up with movable_zone and added memory does not overlap
> + * other zone except for movable zone, the memory is added as movable.
>    * Without this check, movable zone may overlap with other zone.
>    */
>   static int should_add_memory_movable(int nid, u64 start, u64 size)
> @@ -1205,14 +1207,40 @@ static int should_add_memory_movable(int nid, u64 start, u64 size)
>   	unsigned long start_pfn = start >> PAGE_SHIFT;
>   	pg_data_t *pgdat = NODE_DATA(nid);
>   	struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE;
> +	struct zone *zone;
> +	enum zone_type zt = ZONE_MOVABLE - 1;
> +
> +	/*
> +	 * If memory is added after ZONE_MOVALBE, the memory is managed as
> +	 * movable.
> +	 */
> +	if (!zone_is_empty(movable_zone) &&
> +	    (movable_zone->zone_start_pfn <= start_pfn))
> +		return 1;
>   
> -	if (zone_is_empty(movable_zone))
> +	if (!movable_node_is_enabled())
>   		return 0;
>   
> -	if (movable_zone->zone_start_pfn <= start_pfn)
> -		return 1;
> +	/*
> +	 * Find enabled zone and check the added memory.
> +	 * If the memory is added after the enabled zone, the memory is
> +	 * managed as movable.
> +	 *
> +	 * If all zones are empty, the memory is also managed as movable.
> +	 */
> +	for (; zt >= ZONE_DMA; zt--) {
> +		zone = pgdat->node_zones + zt;
>   
> -	return 0;
> +		if (zone_is_empty(zone))
> +			continue;
> +
> +		if (zone_end_pfn(zone) <= start_pfn)
> +			return 1;
> +		else
> +			return 0;
> +	}
> +
> +	return 1;
>   }
>   
>   int zone_for_memory(int nid, u64 start, u64 size, int zone_default)

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