Subject: Re: [RFC PATCH v4 2/13] memory-hotplug : add physical memory hotplug code to acpi_memory_device_remove

From: Yasuaki Ishimatsu <[email-masked]>
Date: Thu, 19 Jul 2012 18:32:59 +0900

Hi Wen,

2012/07/19 16:23, Wen Congyang wrote:
> At 07/18/2012 06:06 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. It only check whether memory is online or not.
>>    - 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 |   27 ++++++++++++++++++++++++++-
>>   drivers/base/memory.c          |   39 +++++++++++++++++++++++++++++++++++++++
>>   include/linux/memory.h         |    5 +++++
>>   include/linux/memory_hotplug.h |    5 +++++
>>   mm/memory_hotplug.c            |   22 ++++++++++++++++++++++
>>   5 files changed, 97 insertions(+), 1 deletion(-)
>>
>> Index: linux-3.5-rc6/drivers/acpi/acpi_memhotplug.c
>> ===================================================================
>> --- linux-3.5-rc6.orig/drivers/acpi/acpi_memhotplug.c	2012-07-17 11:20:15.117796971 +0900
>> +++ linux-3.5-rc6/drivers/acpi/acpi_memhotplug.c	2012-07-17 13:36:30.325594022 +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 +453,36 @@ 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);
>> +	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;
>> +		}
>> +		if (node < 0)
>> +			node = memory_add_physaddr_to_nid(info->start_addr);
>> +
>> +		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	2012-07-17 11:20:15.133796772 +0900
>> +++ linux-3.5-rc6/include/linux/memory_hotplug.h	2012-07-17 11:29:41.490716352 +0900
>> @@ -221,6 +221,7 @@ static inline void unlock_memory_hotplug
>>   #ifdef CONFIG_MEMORY_HOTREMOVE
>>   
>>   extern int is_mem_section_removable(unsigned long pfn, unsigned long nr_pages);
>> +extern int remove_memory(int nid, u64 start, u64 size);
>>   
>>   #else
>>   static inline int is_mem_section_removable(unsigned long pfn,
>> @@ -228,6 +229,10 @@ static inline int is_mem_section_removab
>>   {
>>   	return 0;
>>   }
>> +static inline int remove_memory(int nid, u64 start, u64 size)
>> +{
>> +	return -EBUSY;
>> +}
>>   #endif /* CONFIG_MEMORY_HOTREMOVE */
>>   
>>   extern int mem_online_node(int nid);
>> Index: linux-3.5-rc6/mm/memory_hotplug.c
>> ===================================================================
>> --- linux-3.5-rc6.orig/mm/memory_hotplug.c	2012-07-17 11:20:15.129796821 +0900
>> +++ linux-3.5-rc6/mm/memory_hotplug.c	2012-07-17 13:25:18.952986069 +0900
>> @@ -998,6 +998,28 @@ int offline_memory(u64 start, u64 size)
>>   	end_pfn = start_pfn + PFN_DOWN(size);
>>   	return offline_pages(start_pfn, end_pfn, 120 * HZ);
>>   }
>> +
>> +int remove_memory(int nid, u64 start, u64 size)
>> +{
>> +	int ret = -EBUSY;
>> +	lock_memory_hotplug();
>> +	/*
>> +	 * The memory might become online by other task, even if you offine it.
>> +	 * So we check whether the cpu has been onlined or not.
>> +	 */
>> +	if (!is_memblk_offline(start, size)) {
>> +		pr_warn("memory removing [mem %#010llx-%#010llx] failed, "
>> +			"because the memmory range is online\n",
>> +			start, start + size);
>> +		ret = -EAGAIN;
>> +	}
>> +
>> +	unlock_memory_hotplug();
>> +	return ret;
>> +
>> +}
>> +EXPORT_SYMBOL_GPL(remove_memory);
>> +
>>   #else
>>   int offline_memory(u64 start, u64 size)
>>   {
>> Index: linux-3.5-rc6/drivers/base/memory.c
>> ===================================================================
>> --- linux-3.5-rc6.orig/drivers/base/memory.c	2012-07-17 11:20:15.120796934 +0900
>> +++ linux-3.5-rc6/drivers/base/memory.c	2012-07-17 11:20:54.626302995 +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);
> 
> This line is wrong. I think you want this:
> end_pfn = start_pfn + PFN_UP(size);

Yes. I'll update it.

>> +
>> +	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
>> +		section_nr = pfn_to_section_nr(pfn);
>> +		if (!present_section_nr(section_nr));
> 
> The ';' should be removed. Otherwise, this function always return true...

Thanks. I'll update it.

Thanks,
Yasuaki Ishimatsu

> Thanks
> Wen Congyang
> 
>> +			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	2012-07-17 11:18:00.693477455 +0900
>> +++ linux-3.5-rc6/include/linux/memory.h	2012-07-17 11:20:54.632302919 +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 */
>>
>>
> 
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