[v12,7/8] mm: export symbol of next_zone and first_online_pgdat

This patch enables for_each_zone()/for_each_populated_zone() to be
invoked by a kernel module.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 mm/mmzone.c | 2 ++
 1 file changed, 2 insertions(+)

On Wed, Jul 12, 2017 at 08:40:20PM +0800, Wei Wang wrote:
> This patch enables for_each_zone()/for_each_populated_zone() to be
> invoked by a kernel module.

... for use by virtio balloon.

> Signed-off-by: Wei Wang <wei.w.wang@intel.com>

balloon seems to only use
+       for_each_populated_zone(zone)
+               for_each_migratetype_order(order, type)


> ---
>  mm/mmzone.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/mmzone.c b/mm/mmzone.c
> index a51c0a6..08a2a3a 100644
> --- a/mm/mmzone.c
> +++ b/mm/mmzone.c
> @@ -13,6 +13,7 @@ struct pglist_data *first_online_pgdat(void)
>  {
>  	return NODE_DATA(first_online_node);
>  }
> +EXPORT_SYMBOL_GPL(first_online_pgdat);
>  
>  struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
>  {
> @@ -41,6 +42,7 @@ struct zone *next_zone(struct zone *zone)
>  	}
>  	return zone;
>  }
> +EXPORT_SYMBOL_GPL(next_zone);
>  
>  static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
>  {
> -- 
> 2.7.4

On 07/13/2017 08:16 AM, Michael S. Tsirkin wrote:
> On Wed, Jul 12, 2017 at 08:40:20PM +0800, Wei Wang wrote:
>> This patch enables for_each_zone()/for_each_populated_zone() to be
>> invoked by a kernel module.
> ... for use by virtio balloon.

With this patch, other kernel modules can also use the for_each_zone().
Would it be better to claim it broader?

>
>> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> balloon seems to only use
> +       for_each_populated_zone(zone)
> +               for_each_migratetype_order(order, type)
>

Yes. using for_each_populated_zone() requires the following export.

Best,
Wei
>> ---
>>   mm/mmzone.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/mm/mmzone.c b/mm/mmzone.c
>> index a51c0a6..08a2a3a 100644
>> --- a/mm/mmzone.c
>> +++ b/mm/mmzone.c
>> @@ -13,6 +13,7 @@ struct pglist_data *first_online_pgdat(void)
>>   {
>>   	return NODE_DATA(first_online_node);
>>   }
>> +EXPORT_SYMBOL_GPL(first_online_pgdat);
>>   
>>   struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
>>   {
>> @@ -41,6 +42,7 @@ struct zone *next_zone(struct zone *zone)
>>   	}
>>   	return zone;
>>   }
>> +EXPORT_SYMBOL_GPL(next_zone);
>>   
>>   static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
>>   {
>> -- 
>> 2.7.4
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On Wed 12-07-17 20:40:20, Wei Wang wrote:
> This patch enables for_each_zone()/for_each_populated_zone() to be
> invoked by a kernel module.

This needs much better justification with an example of who is going to
use these symbols and what for.
 
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> ---
>  mm/mmzone.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/mmzone.c b/mm/mmzone.c
> index a51c0a6..08a2a3a 100644
> --- a/mm/mmzone.c
> +++ b/mm/mmzone.c
> @@ -13,6 +13,7 @@ struct pglist_data *first_online_pgdat(void)
>  {
>  	return NODE_DATA(first_online_node);
>  }
> +EXPORT_SYMBOL_GPL(first_online_pgdat);
>  
>  struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
>  {
> @@ -41,6 +42,7 @@ struct zone *next_zone(struct zone *zone)
>  	}
>  	return zone;
>  }
> +EXPORT_SYMBOL_GPL(next_zone);
>  
>  static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
>  {
> -- 
> 2.7.4
> 
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