[PATCH] memory-hotplug: fix not enough check of valid_zones

[Zhang Zhen]

As Yasuaki Ishimatsu described the check here is not enough
if memory has hole as follows:

PFN       0x00          0xd0          0xe0          0xf0
             +-------------+-------------+-------------+
zone type   |   Normal    |     hole    |   Normal    |
             +-------------+-------------+-------------+
In this case, the check can't guarantee that this is "the last
block of memory".
The check of ZONE_MOVABLE has the same problem.

Change the interface name to valid_zones according to most pepole's
suggestion.

Sample output of the sysfs files:
	memory0/valid_zones: none
	memory1/valid_zones: DMA32
	memory2/valid_zones: DMA32
	memory3/valid_zones: DMA32
	memory4/valid_zones: Normal
	memory5/valid_zones: Normal
	memory6/valid_zones: Normal Movable
	memory7/valid_zones: Movable Normal
	memory8/valid_zones: Movable

Signed-off-by: Zhang Zhen <zhenzhang.zhang@xxxxxxxxxx>
---
 Documentation/ABI/testing/sysfs-devices-memory |  8 ++---
 Documentation/memory-hotplug.txt               |  4 +--
 drivers/base/memory.c                          | 42 ++++++--------------------
 3 files changed, 15 insertions(+), 39 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory
index 2b2a1d7..deef3b5 100644
--- a/Documentation/ABI/testing/sysfs-devices-memory
+++ b/Documentation/ABI/testing/sysfs-devices-memory
@@ -61,13 +61,13 @@ Users:		hotplug memory remove tools
 		http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils


-What:           /sys/devices/system/memory/memoryX/zones_online_to
+What:           /sys/devices/system/memory/memoryX/valid_zones
 Date:           July 2014
 Contact:	Zhang Zhen <zhenzhang.zhang@xxxxxxxxxx>
 Description:
-		The file /sys/devices/system/memory/memoryX/zones_online_to
-		is read-only and is designed to show which zone this memory block can
-		be onlined to.
+		The file /sys/devices/system/memory/memoryX/valid_zones	is
+		read-only and is designed to show which zone this memory
+		block can be onlined to.

 What:		/sys/devices/system/memoryX/nodeY
 Date:		October 2009
diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt
index 5b34e33..947229c 100644
--- a/Documentation/memory-hotplug.txt
+++ b/Documentation/memory-hotplug.txt
@@ -155,7 +155,7 @@ Under each memory block, you can see 4 files:
 /sys/devices/system/memory/memoryXXX/phys_device
 /sys/devices/system/memory/memoryXXX/state
 /sys/devices/system/memory/memoryXXX/removable
-/sys/devices/system/memory/memoryXXX/zones_online_to
+/sys/devices/system/memory/memoryXXX/valid_zones

 'phys_index'      : read-only and contains memory block id, same as XXX.
 'state'           : read-write
@@ -171,7 +171,7 @@ Under each memory block, you can see 4 files:
                     block is removable and a value of 0 indicates that
                     it is not removable. A memory block is removable only if
                     every section in the block is removable.
-'zones_online_to' : read-only: designed to show which zone this memory block
+'valid_zones' : read-only: designed to show which zone this memory block
 		    can be onlined to.

 NOTE:
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index ccaf37c..efd456c 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -374,21 +374,7 @@ static ssize_t show_phys_device(struct device *dev,
 }

 #ifdef CONFIG_MEMORY_HOTREMOVE
-static int __zones_online_to(unsigned long end_pfn,
-				struct page *first_page, unsigned long nr_pages)
-{
-	struct zone *zone_next;
-
-	/* The mem block is the last block of memory. */
-	if (!pfn_valid(end_pfn + 1))
-		return 1;
-	zone_next = page_zone(first_page + nr_pages);
-	if (zone_idx(zone_next) == ZONE_MOVABLE)
-		return 1;
-	return 0;
-}
-
-static ssize_t show_zones_online_to(struct device *dev,
+static ssize_t show_valid_zones(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	struct memory_block *mem = to_memory_block(dev);
@@ -407,33 +393,23 @@ static ssize_t show_zones_online_to(struct device *dev,

 	zone = page_zone(first_page);

-#ifdef CONFIG_HIGHMEM
-	if (zone_idx(zone) == ZONE_HIGHMEM) {
-		if (__zones_online_to(end_pfn, first_page, nr_pages))
+	if (zone_idx(zone) == ZONE_MOVABLE - 1) {
+		/*The mem block is the last memoryblock of this zone.*/
+		if (end_pfn == zone_end_pfn(zone))
 			return sprintf(buf, "%s %s\n",
 					zone->name, (zone + 1)->name);
 	}
-#else
-	if (zone_idx(zone) == ZONE_NORMAL) {
-		if (__zones_online_to(end_pfn, first_page, nr_pages))
-			return sprintf(buf, "%s %s\n",
-					zone->name, (zone + 1)->name);
-	}
-#endif

 	if (zone_idx(zone) == ZONE_MOVABLE) {
-		if (!pfn_valid(start_pfn - nr_pages))
-			return sprintf(buf, "%s %s\n",
-						zone->name, (zone - 1)->name);
-		zone_prev = page_zone(first_page - nr_pages);
-		if (zone_idx(zone_prev) != ZONE_MOVABLE)
+		/*The mem block is the first memoryblock of ZONE_MOVABLE.*/
+		if (start_pfn == zone->zone_start_pfn)
 			return sprintf(buf, "%s %s\n",
-						zone->name, (zone - 1)->name);
+					zone->name, (zone - 1)->name);
 	}

 	return sprintf(buf, "%s\n", zone->name);
 }
-static DEVICE_ATTR(zones_online_to, 0444, show_zones_online_to, NULL);
+static DEVICE_ATTR(valid_zones, 0444, show_valid_zones, NULL);
 #endif

 static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
@@ -587,7 +563,7 @@ static struct attribute *memory_memblk_attrs[] = {
 	&dev_attr_phys_device.attr,
 	&dev_attr_removable.attr,
 #ifdef CONFIG_MEMORY_HOTREMOVE
-	&dev_attr_zones_online_to.attr,
+	&dev_attr_valid_zones.attr,
 #endif
 	NULL
 };
-- 
1.8.1.4


.




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