memory-hotplug: fix not enough check of valid zones

Rename the interface 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 <[email protected]>

---
  Documentation/ABI/testing/sysfs-devices-memory |  8 ++++----
  Documentation/memory-hotplug.txt               | 13 ++++++++++---
  drivers/base/memory.c                          |  6 +++---
  3 files changed, 17 insertions(+), 10 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +4 -4

index 2b2a1d7..deef3b5 100644
@@ -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 <[email protected]>
  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

Documentation/memory-hotplug.txt +10 -3

index 5b34e33..93a25ef 100644
@@ -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

@@ -171,8 +171,15 @@ 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
-		    can be onlined to.
+'valid_zones'     : read-only: designed to show which zones this memory block
+		    can be onlined to.
+		    The first column shows it's default zone.
+		    "memory6/valid_zones: Normal Movable" shows this memoryblock
+		    can be onlined to ZONE_NORMAL by default and to ZONE_MOVABLE
+		    by online_movable.
+		    "memory7/valid_zones: Movable Normal" shows this memoryblock
+		    can be onlined to ZONE_MOVABLE by default and to ZONE_NORMAL
+		    by online_kernel.
 
  NOTE:
    These directories/files appear after physical memory hotplug phase.

drivers/base/memory.c +2 -2

index 0fc1d25..efd456c 100644
@@ -374,7 +374,7 @@ static ssize_t show_phys_device(struct device *dev,
  }
 
  #ifdef CONFIG_MEMORY_HOTREMOVE
-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);

@@ -409,7 +409,7 @@ static ssize_t show_zones_online_to(struct device *dev,
 
  	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);

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.

Signed-off-by Zhang Zhen <[email protected]>

---
  drivers/base/memory.c | 36 ++++++------------------------------
  1 file changed, 6 insertions(+), 30 deletions(-)

drivers/base/memory.c +3 -27

index ccaf37c..0fc1d25 100644
@@ -374,20 +374,6 @@ 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,
  				struct device_attribute *attr, char *buf)
  {

@@ -407,28 +393,18 @@ 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);