Re: [RFC v9 PATCH 04/21] memory-hotplug: offline and remove memory when removing the memory device

[Ni zhan Chen <nizhan.chen@gmail.com>]

On 09/05/2012 05:25 PM, wency@cn.fujitsu.com wrote:
> From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>
> We should offline and remove memory when removing the memory device.
> The memory device can be removed by 2 ways:
> 1. send eject request by SCI
> 2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject
>
> In the 1st case, acpi_memory_disable_device() will be called. In the 2nd
> case, acpi_memory_device_remove() will be called. acpi_memory_device_remove()
> will also be called when we unbind the memory device from the driver
> acpi_memhotplug. If the type is ACPI_BUS_REMOVAL_EJECT, it means
> that the user wants to eject the memory device, and we should offline
> and remove memory in acpi_memory_device_remove().
>
> The function remove_memory() is not implemeted now. It only check whether
> all memory has been offllined now.
>
> CC: David Rientjes <rientjes@google.com>
> CC: Jiang Liu <liuj97@gmail.com>
> CC: Len Brown <len.brown@intel.com>
> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> CC: Paul Mackerras <paulus@samba.org>
> CC: Christoph Lameter <cl@linux.com>
> Cc: Minchan Kim <minchan.kim@gmail.com>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>   drivers/acpi/acpi_memhotplug.c |   45 +++++++++++++++++++++++++++++++++------
>   drivers/base/memory.c          |   39 ++++++++++++++++++++++++++++++++++
>   include/linux/memory.h         |    5 ++++
>   include/linux/memory_hotplug.h |    5 ++++
>   mm/memory_hotplug.c            |   22 +++++++++++++++++++
>   5 files changed, 109 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index 7873832..9d47458 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -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>
> @@ -310,25 +311,44 @@ static int acpi_memory_powerdown_device(struct acpi_memory_device *mem_device)
>   	return 0;
>   }
>   
> -static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
> +static int
> +acpi_memory_device_remove_memory(struct acpi_memory_device *mem_device)
>   {
>   	int result;
>   	struct acpi_memory_info *info, *n;
> +	int node = mem_device->nid;
>   
> -
> -	/*
> -	 * Ask the VM to offline this memory range.
> -	 * Note: Assume that this function returns zero on success
> -	 */
>   	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
>   		if (info->enabled) {
>   			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);
>   	}
>   
> +	return 0;
> +}
> +
> +static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
> +{
> +	int result;
> +
> +	/*
> +	 * Ask the VM to offline this memory range.
> +	 * Note: Assume that this function returns zero on success
> +	 */
> +	result = acpi_memory_device_remove_memory(mem_device);
> +	if (result)
> +		return result;
> +
>   	/* Power-off and eject the device */
>   	result = acpi_memory_powerdown_device(mem_device);
>   	if (result) {
> @@ -477,12 +497,23 @@ static int acpi_memory_device_add(struct acpi_device *device)
>   static int acpi_memory_device_remove(struct acpi_device *device, int type)
>   {
>   	struct acpi_memory_device *mem_device = NULL;
> -
> +	int result;
>   
>   	if (!device || !acpi_driver_data(device))
>   		return -EINVAL;
>   
>   	mem_device = acpi_driver_data(device);
> +
> +	if (type == ACPI_BUS_REMOVAL_EJECT) {
> +		/*
> +		 * offline and remove memory only when the memory device is
> +		 * ejected.
> +		 */
> +		result = acpi_memory_device_remove_memory(mem_device);
> +		if (result)
> +			return result;
> +	}
> +
>   	kfree(mem_device);
>   
>   	return 0;
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 86c8821..038be73 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -70,6 +70,45 @@ void unregister_memory_isolate_notifier(struct notifier_block *nb)
>   }
>   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 = PFN_UP(start + size);
> +
> +	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
>    */
> diff --git a/include/linux/memory.h b/include/linux/memory.h
> index 1ac7f6e..7c66126 100644
> --- a/include/linux/memory.h
> +++ b/include/linux/memory.h
> @@ -106,6 +106,10 @@ static inline int memory_isolate_notify(unsigned long val, void *v)
>   {
>   	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(unsigned long val, void *v);
>   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 */
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 0b040bb..fd84ea9 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -222,6 +222,7 @@ static inline void unlock_memory_hotplug(void) {}
>   #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,
> @@ -229,6 +230,10 @@ static inline int is_mem_section_removable(unsigned long pfn,
>   {
>   	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);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 6fc1908..49f7747 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1038,6 +1038,28 @@ int offline_memory(u64 start, u64 size)
>   
>   	return 0;
>   }
> +
> +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.

s/offine/offline

> +	 * So we check whether the memory 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_pages(unsigned long start, unsigned long size)
>   {