[RFC PATCH v4 7/13] memory-hotplug : remove_memory calls __remove_pages

[Yasuaki Ishimatsu]

The patch adds __remove_pages() to remove_memory(). Then the range of
phys_start_pfn argument and nr_pages argument in __remove_pagse() may
have different zone. So zone argument is removed from __remove_pages()
and __remove_pages() caluculates zone in each section.

When CONFIG_SPARSEMEM_VMEMMAP is defined, there is no way to remove a memmap.
So __remove_section only calls unregister_memory_section().

CC: David Rientjes <rientjes at google.com>
CC: Jiang Liu <liuj97 at gmail.com>
CC: Len Brown <len.brown at intel.com>
CC: Benjamin Herrenschmidt <benh at kernel.crashing.org>
CC: Paul Mackerras <paulus at samba.org> 
CC: Christoph Lameter <cl at linux.com>
Cc: Minchan Kim <minchan.kim at gmail.com>
CC: Andrew Morton <akpm at linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro at jp.fujitsu.com> 
CC: Wen Congyang <wency at cn.fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki at jp.fujitsu.com>

---
 arch/powerpc/platforms/pseries/hotplug-memory.c |    5 +----
 include/linux/memory_hotplug.h                  |    3 +--
 mm/memory_hotplug.c                             |   19 ++++++++++++-------
 3 files changed, 14 insertions(+), 13 deletions(-)

Index: linux-3.5-rc6/mm/memory_hotplug.c
===================================================================
--- linux-3.5-rc6.orig/mm/memory_hotplug.c	2012-07-18 18:00:27.440145432 +0900
+++ linux-3.5-rc6/mm/memory_hotplug.c	2012-07-18 18:01:02.070712487 +0900
@@ -275,11 +275,14 @@ static int __meminit __add_section(int n
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 static int __remove_section(struct zone *zone, struct mem_section *ms)
 {
-	/*
-	 * XXX: Freeing memmap with vmemmap is not implement yet.
-	 *      This should be removed later.
-	 */
-	return -EBUSY;
+	int ret = -EINVAL;
+
+	if (!valid_section(ms))
+		return ret;
+
+	ret = unregister_memory_section(ms);
+
+	return ret;
 }
 #else
 static int __remove_section(struct zone *zone, struct mem_section *ms)
@@ -346,11 +349,11 @@ EXPORT_SYMBOL_GPL(__add_pages);
  * sure that pages are marked reserved and zones are adjust properly by
  * calling offline_pages().
  */
-int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
-		 unsigned long nr_pages)
+int __remove_pages(unsigned long phys_start_pfn, unsigned long nr_pages)
 {
 	unsigned long i, ret = 0;
 	int sections_to_remove;
+	struct zone *zone;
 
 	/*
 	 * We can only remove entire sections
@@ -363,6 +366,7 @@ int __remove_pages(struct zone *zone, un
 	sections_to_remove = nr_pages / PAGES_PER_SECTION;
 	for (i = 0; i < sections_to_remove; i++) {
 		unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
+		zone = page_zone(pfn_to_page(pfn));
 		ret = __remove_section(zone, __pfn_to_section(pfn));
 		if (ret)
 			break;
@@ -1031,6 +1035,7 @@ int __ref remove_memory(int nid, u64 sta
 	/* remove memmap entry */
 	firmware_map_remove(start, start + size, "System RAM");
 
+	__remove_pages(start >> PAGE_SHIFT, size >> PAGE_SHIFT);
 out:
 	unlock_memory_hotplug();
 	return ret;
Index: linux-3.5-rc6/include/linux/memory_hotplug.h
===================================================================
--- linux-3.5-rc6.orig/include/linux/memory_hotplug.h	2012-07-18 18:00:27.445145371 +0900
+++ linux-3.5-rc6/include/linux/memory_hotplug.h	2012-07-18 18:00:40.461982690 +0900
@@ -89,8 +89,7 @@ extern bool is_pageblock_removable_noloc
 /* reasonably generic interface to expand the physical pages in a zone  */
 extern int __add_pages(int nid, struct zone *zone, unsigned long start_pfn,
 	unsigned long nr_pages);
-extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
-	unsigned long nr_pages);
+extern int __remove_pages(unsigned long start_pfn, unsigned long nr_pages);
 
 #ifdef CONFIG_NUMA
 extern int memory_add_physaddr_to_nid(u64 start);
Index: linux-3.5-rc6/arch/powerpc/platforms/pseries/hotplug-memory.c
===================================================================
--- linux-3.5-rc6.orig/arch/powerpc/platforms/pseries/hotplug-memory.c	2012-07-18 18:00:27.442145407 +0900
+++ linux-3.5-rc6/arch/powerpc/platforms/pseries/hotplug-memory.c	2012-07-18 18:00:40.470982578 +0900
@@ -76,7 +76,6 @@ unsigned long memory_block_size_bytes(vo
 static int pseries_remove_memblock(unsigned long base, unsigned int memblock_size)
 {
 	unsigned long start, start_pfn;
-	struct zone *zone;
 	int i, ret;
 	int sections_to_remove;
 
@@ -87,8 +86,6 @@ static int pseries_remove_memblock(unsig
 		return 0;
 	}
 
-	zone = page_zone(pfn_to_page(start_pfn));
-
 	/*
 	 * Remove section mappings and sysfs entries for the
 	 * section of the memory we are removing.
@@ -101,7 +98,7 @@ static int pseries_remove_memblock(unsig
 	sections_to_remove = (memblock_size >> PAGE_SHIFT) / PAGES_PER_SECTION;
 	for (i = 0; i < sections_to_remove; i++) {
 		unsigned long pfn = start_pfn + i * PAGES_PER_SECTION;
-		ret = __remove_pages(zone, start_pfn,  PAGES_PER_SECTION);
+		ret = __remove_pages(start_pfn,  PAGES_PER_SECTION);
 		if (ret)
 			return ret;
 	}