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

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(2014/08/27 10:55), Zhang Zhen wrote:
On 2014/8/26 18:23, Yasuaki Ishimatsu wrote:
(2014/08/26 18:57), Zhang Zhen wrote:
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

The patch has two changes:
  - change sysfs interface name
  - change check of ZONE_MOVABLE
So please separate them.

Ok, i will separate them.

Thanks!
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);

How about swap zone->name and (zone - 1)->name.

If swapping them, sample output of the sysfs files shows as follows:
      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: Normal Movable

	memory6/valid_zones: Normal Movable
	memory7/valid_zones: Movable Normal
Here can better show the dividing line between ZONE_MOVABLE and ZONE_NORMAL.


The first column shows it's default zone,

If so, please write the information in 'valid_zones' term
of memory-hotplug.txt. Nobody know it.

Thanks,
Yasuaki Ishimatasu

for memory6:
	the first column Normal shows that it can be onlined to ZONE_NORMAL by default.
	echo offline > memory6/state
	echo online > memory6/state
	the second column Movable shows that it can be onlined to ZONE_MOVABLE by online_movable.
	echo offline > memory6/state
	echo online_movable > memory6/state
for memory7:
	the first column Movable shows that it can be onlined to ZONE_MOVABLE by default.
	echo offline > memory7/state
	echo online > memory7/state
	the second column Normal shows that it can be onlined to ZONE_NORMAL by online_kernel.
	echo offline > memory7/state
	echo online_kernel > memory7/state

And it is more convenient for script to work.
So i think we should leave it as it is.

Thanks!
                              ~~~~~~~~~~~~~~
      memory8/valid_zones: Movable

Thanks,
Yasuaki Ishimatsu

       }

       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
   };




.





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