Re: [RFC PATCH 1/4] mm/hotplug: aligne the hotplugable range with memory_block

[Wei Yang <richard.weiyang@gmail.com>]

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On Sat, Jun 24, 2017 at 08:31:20PM -0700, John Hubbard wrote:
>On 06/24/2017 07:52 PM, Wei Yang wrote:
>> memory hotplug is memory block aligned instead of section aligned.
>> 
>> This patch fix the range check during hotplug.
>> 
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>> ---
>>  drivers/base/memory.c  | 3 ++-
>>  include/linux/memory.h | 2 ++
>>  mm/memory_hotplug.c    | 9 +++++----
>>  3 files changed, 9 insertions(+), 5 deletions(-)
>> 
>> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
>> index c7c4e0325cdb..b54cfe9cd98b 100644
>> --- a/drivers/base/memory.c
>> +++ b/drivers/base/memory.c
>> @@ -31,7 +31,8 @@ static DEFINE_MUTEX(mem_sysfs_mutex);
>>  
>>  #define to_memory_block(dev) container_of(dev, struct memory_block, dev)
>>  
>> -static int sections_per_block;
>> +int sections_per_block;
>> +EXPORT_SYMBOL(sections_per_block);
>
>Hi Wei,
>
>Is sections_per_block ever assigned a value? I am not seeing that happen,
>either in this patch, or in the larger patchset.
>

This is assigned in memory_dev_init(). Not in my patch.

>
>>  
>>  static inline int base_memory_block_id(int section_nr)
>>  {
>> diff --git a/include/linux/memory.h b/include/linux/memory.h
>> index b723a686fc10..51a6355aa56d 100644
>> --- a/include/linux/memory.h
>> +++ b/include/linux/memory.h
>> @@ -142,4 +142,6 @@ extern struct memory_block *find_memory_block(struct mem_section *);
>>   */
>>  extern struct mutex text_mutex;
>>  
>> +extern int sections_per_block;
>> +
>>  #endif /* _LINUX_MEMORY_H_ */
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 387ca386142c..f5d06afc8645 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1183,11 +1183,12 @@ static int check_hotplug_memory_range(u64 start, u64 size)
>>  {
>>  	u64 start_pfn = PFN_DOWN(start);
>>  	u64 nr_pages = size >> PAGE_SHIFT;
>> +	u64 page_per_block = sections_per_block * PAGES_PER_SECTION;
>
>"pages_per_block" would be a little better.
>
>Also, in the first line of the commit, s/aligne/align/.

Good, thanks.

>
>thanks,
>john h
>
>>  
>> -	/* Memory range must be aligned with section */
>> -	if ((start_pfn & ~PAGE_SECTION_MASK) ||
>> -	    (nr_pages % PAGES_PER_SECTION) || (!nr_pages)) {
>> -		pr_err("Section-unaligned hotplug range: start 0x%llx, size 0x%llx\n",
>> +	/* Memory range must be aligned with memory_block */
>> +	if ((start_pfn & (page_per_block - 1)) ||
>> +	    (nr_pages % page_per_block) || (!nr_pages)) {
>> +		pr_err("Memory_block-unaligned hotplug range: start 0x%llx, size 0x%llx\n",
>>  				(unsigned long long)start,
>>  				(unsigned long long)size);
>>  		return -EINVAL;
>> 

-- 
Wei Yang
Help you, Help me

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