[RFC v8 PATCH 09/20] memory-hotplug: does not release memory region in PAGES_PER_SECTION chunks

[wency at cn.fujitsu.com]

From: Yasuaki Ishimatsu <isimatu.yasuaki at jp.fujitsu.com>

Since applying a patch(de7f0cba96786c), release_mem_region() has been changed
as called in PAGES_PER_SECTION chunks because register_memory_resource() is
called in PAGES_PER_SECTION chunks by add_memory(). But it seems firmware
dependency. If CRS are written in the PAGES_PER_SECTION chunks in ACPI DSDT
Table, register_memory_resource() is called in PAGES_PER_SECTION chunks.
But if CRS are written in the DIMM unit in ACPI DSDT Table,
register_memory_resource() is called in DIMM unit. So release_mem_region()
should not be called in PAGES_PER_SECTION chunks. The patch fixes it.

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 |   13 +++++++++----
 mm/memory_hotplug.c                             |    4 ++--
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 11d8e05..dc0a035 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -77,7 +77,8 @@ static int pseries_remove_memblock(unsigned long base, unsigned int memblock_siz
 {
 	unsigned long start, start_pfn;
 	struct zone *zone;
-	int ret;
+	int i, ret;
+	int sections_to_remove;
 
 	start_pfn = base >> PAGE_SHIFT;
 
@@ -97,9 +98,13 @@ static int pseries_remove_memblock(unsigned long base, unsigned int memblock_siz
 	 * to sysfs "state" file and we can't remove sysfs entries
 	 * while writing to it. So we have to defer it to here.
 	 */
-	ret = __remove_pages(zone, start_pfn, memblock_size >> PAGE_SHIFT);
-	if (ret)
-		return ret;
+	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);
+		if (ret)
+			return ret;
+	}
 
 	/*
 	 * Update memory regions for memory remove
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 45b03b3..29aff4d 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -358,11 +358,11 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 	BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
 	BUG_ON(nr_pages % PAGES_PER_SECTION);
 
+	release_mem_region(phys_start_pfn << PAGE_SHIFT,  nr_pages * PAGE_SIZE);
+
 	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;
-		release_mem_region(pfn << PAGE_SHIFT,
-				   PAGES_PER_SECTION << PAGE_SHIFT);
 		ret = __remove_section(zone, __pfn_to_section(pfn));
 		if (ret)
 			break;
-- 
1.7.1