Subject: Re: [RFC v9 PATCH 01/21] memory-hotplug: rename remove_memory() to offline_memory()/offline_pages()

From: Ni zhan Chen <[email-masked]>
Date: Fri, 28 Sep 2012 10:22:28 +0800

On 09/05/2012 05:25 PM, [email-masked] wrote:
> From: Yasuaki Ishimatsu <[email-masked]>
>
> remove_memory() only try to offline pages. It is called in two cases:
> 1. hot remove a memory device
> 2. echo offline >/sys/devices/system/memory/memoryXX/state
>
> In the 1st case, we should also change memory block's state, and notify
> the userspace that the memory block's state is changed after offlining
> pages.
>
> So rename remove_memory() to offline_memory()/offline_pages(). And in
> the 1st case, offline_memory() will be used. The function offline_memory()
> is not implemented. In the 2nd case, offline_pages() will be used.

But this time there is not a function associated with add_memory.

>
> CC: David Rientjes <[email-masked]>
> CC: Jiang Liu <[email-masked]>
> CC: Len Brown <[email-masked]>
> CC: Benjamin Herrenschmidt <[email-masked]>
> CC: Paul Mackerras <[email-masked]>
> CC: Christoph Lameter <[email-masked]>
> Cc: Minchan Kim <[email-masked]>
> CC: Andrew Morton <[email-masked]>
> CC: KOSAKI Motohiro <[email-masked]>
> Signed-off-by: Yasuaki Ishimatsu <[email-masked]>
> Signed-off-by: Wen Congyang <[email-masked]>
> ---
>   drivers/acpi/acpi_memhotplug.c |    2 +-
>   drivers/base/memory.c          |    9 +++------
>   include/linux/memory_hotplug.h |    3 ++-
>   mm/memory_hotplug.c            |   22 ++++++++++++++--------
>   4 files changed, 20 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index 24c807f..2a7beac 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -318,7 +318,7 @@ static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
>   	 */
>   	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
>   		if (info->enabled) {
> -			result = remove_memory(info->start_addr, info->length);
> +			result = offline_memory(info->start_addr, info->length);
>   			if (result)
>   				return result;
>   		}
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 7dda4f7..44e7de6 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -248,26 +248,23 @@ static bool pages_correctly_reserved(unsigned long start_pfn,
>   static int
>   memory_block_action(unsigned long phys_index, unsigned long action)
>   {
> -	unsigned long start_pfn, start_paddr;
> +	unsigned long start_pfn;
>   	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
>   	struct page *first_page;
>   	int ret;
>   
>   	first_page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
> +	start_pfn = page_to_pfn(first_page);
>   
>   	switch (action) {
>   		case MEM_ONLINE:
> -			start_pfn = page_to_pfn(first_page);
> -
>   			if (!pages_correctly_reserved(start_pfn, nr_pages))
>   				return -EBUSY;
>   
>   			ret = online_pages(start_pfn, nr_pages);
>   			break;
>   		case MEM_OFFLINE:
> -			start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
> -			ret = remove_memory(start_paddr,
> -					    nr_pages << PAGE_SHIFT);
> +			ret = offline_pages(start_pfn, nr_pages);
>   			break;
>   		default:
>   			WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 910550f..c183f39 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -233,7 +233,8 @@ static inline int is_mem_section_removable(unsigned long pfn,
>   extern int mem_online_node(int nid);
>   extern int add_memory(int nid, u64 start, u64 size);
>   extern int arch_add_memory(int nid, u64 start, u64 size);
> -extern int remove_memory(u64 start, u64 size);
> +extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
> +extern int offline_memory(u64 start, u64 size);
>   extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
>   								int nr_pages);
>   extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 3ad25f9..bb42316 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -866,7 +866,7 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
>   	return offlined;
>   }
>   
> -static int __ref offline_pages(unsigned long start_pfn,
> +static int __ref __offline_pages(unsigned long start_pfn,
>   		  unsigned long end_pfn, unsigned long timeout)
>   {
>   	unsigned long pfn, nr_pages, expire;
> @@ -994,18 +994,24 @@ out:
>   	return ret;
>   }
>   
> -int remove_memory(u64 start, u64 size)
> +int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
>   {
> -	unsigned long start_pfn, end_pfn;
> +	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
> +}
>   
> -	start_pfn = PFN_DOWN(start);
> -	end_pfn = start_pfn + PFN_DOWN(size);
> -	return offline_pages(start_pfn, end_pfn, 120 * HZ);
> +int offline_memory(u64 start, u64 size)
> +{
> +	return -EINVAL;
>   }
>   #else
> -int remove_memory(u64 start, u64 size)
> +int offline_pages(unsigned long start, unsigned long size)
> +{
> +	return -EINVAL;
> +}
> +
> +int offline_memory(u64 start, u64 size)
>   {
>   	return -EINVAL;
>   }
>   #endif /* CONFIG_MEMORY_HOTREMOVE */
> -EXPORT_SYMBOL_GPL(remove_memory);
> +EXPORT_SYMBOL_GPL(offline_memory);