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

From: Yasuaki Ishimatsu <[email-masked]>
Date: Wed, 18 Jul 2012 19:06:49 +0900

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);
+
+	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	2012-07-17 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 */