Subject: Re: [RFC PATCH v3 2/13] memory-hotplug : add physical memory hotplug code to acpi_memory_device_remove

From: Wen Congyang <[email-masked]>
Date: Fri, 13 Jul 2012 18:40:56 +0800

At 07/09/2012 06:24 PM, Yasuaki Ishimatsu Wrote:
> acpi_memory_device_remove() has been prepared to remove physical memory.
> But, the function only frees acpi_memory_device currentlry.
> 
> The patch adds following functions into acpi_memory_device_remove():
>   - offline memory
>   - remove physical memory (only return -EBUSY)
>   - free acpi_memory_device
> 
> 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]>
> CC: Wen Congyang <[email-masked]>
> Signed-off-by: Yasuaki Ishimatsu <[email-masked]>
> 
> ---
>  drivers/acpi/acpi_memhotplug.c |   26 +++++++++++++++++++++++++-
>  drivers/base/memory.c          |   39 +++++++++++++++++++++++++++++++++++++++
>  include/linux/memory.h         |    5 +++++
>  include/linux/memory_hotplug.h |    1 +
>  mm/memory_hotplug.c            |    8 ++++++++
>  5 files changed, 78 insertions(+), 1 deletion(-)
> 
> Index: linux-3.5-rc6/drivers/acpi/acpi_memhotplug.c
> ===================================================================
> --- linux-3.5-rc6.orig/drivers/acpi/acpi_memhotplug.c	2012-07-09 18:08:29.946888653 +0900
> +++ linux-3.5-rc6/drivers/acpi/acpi_memhotplug.c	2012-07-09 18:08:43.470719531 +0900
> @@ -29,6 +29,7 @@
>  #include <linux/module.h>
>  #include <linux/init.h>
>  #include <linux/types.h>
> +#include <linux/memory.h>
>  #include <linux/memory_hotplug.h>
>  #include <linux/slab.h>
>  #include <acpi/acpi_drivers.h>
> @@ -452,12 +453,35 @@ static int acpi_memory_device_add(struct
>  static int acpi_memory_device_remove(struct acpi_device *device, int type)
>  {
>  	struct acpi_memory_device *mem_device = NULL;
> -
> +	struct acpi_memory_info *info, *tmp;
> +	int result;
> +	int node;
> 
>  	if (!device || !acpi_driver_data(device))
>  		return -EINVAL;
> 
>  	mem_device = acpi_driver_data(device);
> +
> +	node = acpi_get_node(mem_device->device->handle);

acpi_get_node() may return -1, and you should call memory_add_physaddr_to_nid()
to get the node id.

Thanks
Wen Congyang

> +
> +	list_for_each_entry_safe(info, tmp, &mem_device->res_list, list) {
> +		if (!info->enabled)
> +			continue;
> +
> +		if (!is_memblk_offline(info->start_addr, info->length)) {
> +			result = offline_memory(info->start_addr, info->length);
> +			if (result)
> +				return result;
> +		}
> +
> +		result = remove_memory(node, info->start_addr, info->length);
> +		if (result)
> +			return result;
> +
> +		list_del(&info->list);
> +		kfree(info);
> +	}
> +
>  	kfree(mem_device);
> 
>  	return 0;
> Index: linux-3.5-rc6/include/linux/memory_hotplug.h
> ===================================================================
> --- linux-3.5-rc6.orig/include/linux/memory_hotplug.h	2012-07-09 18:08:29.955888542 +0900
> +++ linux-3.5-rc6/include/linux/memory_hotplug.h	2012-07-09 18:08:43.471719518 +0900
> @@ -233,6 +233,7 @@ static inline int is_mem_section_removab
>  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(int nid, u64 start, u64 size);
>  extern int offline_memory(u64 start, u64 size);
>  extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
>  								int nr_pages);
> Index: linux-3.5-rc6/mm/memory_hotplug.c
> ===================================================================
> --- linux-3.5-rc6.orig/mm/memory_hotplug.c	2012-07-09 18:08:29.953888567 +0900
> +++ linux-3.5-rc6/mm/memory_hotplug.c	2012-07-09 18:08:43.476719455 +0900
> @@ -659,6 +659,14 @@ out:
>  }
>  EXPORT_SYMBOL_GPL(add_memory);
> 
> +int remove_memory(int nid, u64 start, u64 size)
> +{
> +	return -EBUSY;
> +
> +}
> +EXPORT_SYMBOL_GPL(remove_memory);
> +
> +
>  #ifdef CONFIG_MEMORY_HOTREMOVE
>  /*
>   * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
> Index: linux-3.5-rc6/drivers/base/memory.c
> ===================================================================
> --- linux-3.5-rc6.orig/drivers/base/memory.c	2012-07-09 18:08:29.947888640 +0900
> +++ linux-3.5-rc6/drivers/base/memory.c	2012-07-09 18:10:54.880076739 +0900
> @@ -70,6 +70,45 @@ void unregister_memory_isolate_notifier(
>  }
>  EXPORT_SYMBOL(unregister_memory_isolate_notifier);
> 
> +bool is_memblk_offline(unsigned long start, unsigned long size)
> +{
> +	struct memory_block *mem = NULL;
> +	struct mem_section *section;
> +	unsigned long start_pfn, end_pfn;
> +	unsigned long pfn, section_nr;
> +
> +	start_pfn = PFN_DOWN(start);
> +	end_pfn = start_pfn + PFN_DOWN(start);
> +
> +	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
> +		section_nr = pfn_to_section_nr(pfn);
> +		if (!present_section_nr(section_nr));
> +			continue;
> +
> +		section = __nr_to_section(section_nr);
> +		/* same memblock? */
> +		if (mem)
> +			if((section_nr >= mem->start_section_nr) &&
> +			   (section_nr <= mem->end_section_nr))
> +				continue;
> +
> +		mem = find_memory_block_hinted(section, mem);
> +		if (!mem)
> +			continue;
> +		if (mem->state == MEM_OFFLINE)
> +			continue;
> +
> +		kobject_put(&mem->dev.kobj);
> +		return false;
> +	}
> +
> +	if (mem)
> +		kobject_put(&mem->dev.kobj);
> +
> +	return true;
> +}
> +EXPORT_SYMBOL(is_memblk_offline);
> +
>  /*
>   * register_memory - Setup a sysfs device for a memory block
>   */
> Index: linux-3.5-rc6/include/linux/memory.h
> ===================================================================
> --- linux-3.5-rc6.orig/include/linux/memory.h	2012-07-08 09:23:56.000000000 +0900
> +++ linux-3.5-rc6/include/linux/memory.h	2012-07-09 18:08:43.484719355 +0900
> @@ -106,6 +106,10 @@ static inline int memory_isolate_notify(
>  {
>  	return 0;
>  }
> +static inline bool is_memblk_offline(unsigned long start, unsigned long size)
> +{
> +	return false;
> +}
>  #else
>  extern int register_memory_notifier(struct notifier_block *nb);
>  extern void unregister_memory_notifier(struct notifier_block *nb);
> @@ -120,6 +124,7 @@ extern int memory_isolate_notify(unsigne
>  extern struct memory_block *find_memory_block_hinted(struct mem_section *,
>  							struct memory_block *);
>  extern struct memory_block *find_memory_block(struct mem_section *);
> +extern bool is_memblk_offline(unsigned long start, unsigned long size);
>  #define CONFIG_MEM_BLOCK_SIZE	(PAGES_PER_SECTION<<PAGE_SHIFT)
>  enum mem_add_context { BOOT, HOTPLUG };
>  #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
> 
>