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

[John Hubbard <jhubbard@nvidia.com>]

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.


>  
>  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/.

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;
> 

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