memory-hotplug: add sysfs zones_online_to attribute

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

---
 Documentation/ABI/testing/sysfs-devices-memory |  8 ++++
 Documentation/memory-hotplug.txt               |  4 +-
 drivers/base/memory.c                          | 62 ++++++++++++++++++++++++++
 include/linux/memory_hotplug.h                 |  1 +
 mm/memory_hotplug.c                            |  2 +-
 5 files changed, 75 insertions(+), 2 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +0 -0

index 7405de2..2b2a1d7 100644

Quoted 31 lines · Zhang Zhen

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

---
 Documentation/ABI/testing/sysfs-devices-memory |  8 ++++
 Documentation/memory-hotplug.txt               |  4 +-
 drivers/base/memory.c                          | 62 ++++++++++++++++++++++++++
 include/linux/memory_hotplug.h                 |  1 +
 mm/memory_hotplug.c                            |  2 +-
 5 files changed, 75 insertions(+), 2 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +0 -0

index 7405de2..2b2a1d7 100644
@@ -61,6 +61,14 @@ Users:		hotplug memory remove tools
 		http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
 
 

Documentation/ABI/testing/sysfs-devices-memory Users: hotplug memory remove tools · line 64

Quoted 1 line

Documentation/ABI/testing/sysfs-devices-memory +1 -0

+What:           /sys/devices/system/memory/memoryX/zones_online_to

I think this name is a bit confusing. How about "valid_online_types"?

Thanks,
-Toshi

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Quoted 32 lines · Toshi Kani

Quoted 31 lines · Zhang Zhen

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

---
  Documentation/ABI/testing/sysfs-devices-memory |  8 ++++
  Documentation/memory-hotplug.txt               |  4 +-
  drivers/base/memory.c                          | 62 ++++++++++++++++++++++++++
  include/linux/memory_hotplug.h                 |  1 +
  mm/memory_hotplug.c                            |  2 +-
  5 files changed, 75 insertions(+), 2 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +0 -0

index 7405de2..2b2a1d7 100644
@@ -61,6 +61,14 @@ Users:		hotplug memory remove tools
  		http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
 
 

Quoted 4 lines

Documentation/ABI/testing/sysfs-devices-memory Users: hotplug memory remove tools · line 64

Quoted 1 line

Documentation/ABI/testing/sysfs-devices-memory +1 -0

+What:           /sys/devices/system/memory/memoryX/zones_online_to

I think this name is a bit confusing. How about "valid_online_types"?

Thanks for your suggestion.

This patch has been added to -mm tree.
If most people think so, i would like to modify the interface name.

If not, let's leave it as it is.

Best regards!

Quoted 12 lines

Thanks,
-Toshi

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To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Quoted 32 lines · Toshi Kani

Quoted 31 lines · Zhang Zhen

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

---
 Documentation/ABI/testing/sysfs-devices-memory |  8 ++++
 Documentation/memory-hotplug.txt               |  4 +-
 drivers/base/memory.c                          | 62 ++++++++++++++++++++++++++
 include/linux/memory_hotplug.h                 |  1 +
 mm/memory_hotplug.c                            |  2 +-
 5 files changed, 75 insertions(+), 2 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +0 -0

index 7405de2..2b2a1d7 100644
@@ -61,6 +61,14 @@ Users:		hotplug memory remove tools
 		http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
 
 

Quoted 4 lines

Documentation/ABI/testing/sysfs-devices-memory Users: hotplug memory remove tools · line 64

Quoted 1 line

Documentation/ABI/testing/sysfs-devices-memory +1 -0

+What:           /sys/devices/system/memory/memoryX/zones_online_to

I think this name is a bit confusing. How about "valid_online_types"?

Thanks for your suggestion.

This patch has been added to -mm tree.
If most people think so, i would like to modify the interface name. If not, let's leave it as it is.

Also, it's not really clear to me why we need this sysfs file at all. Do people really read sysfs files, make onlining decisions and manually type in commands? Or is this stuff all automated? If the latter then the script can take care of all this? For example, attempt to online the memory into the desired zone and report failure if that didn't succeed?

Quoted 37 lines · On Mon, 18 Aug 2014 11:25:36 +0800 Zhang Zhen <[email protected]>…

Quoted 36 lines · Toshi Kani

Quoted 28 lines · Zhang Zhen

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

---
 Documentation/ABI/testing/sysfs-devices-memory |  8 ++++
 Documentation/memory-hotplug.txt               |  4 +-
 drivers/base/memory.c                          | 62 ++++++++++++++++++++++++++
 include/linux/memory_hotplug.h                 |  1 +
 mm/memory_hotplug.c                            |  2 +-
 5 files changed, 75 insertions(+), 2 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +0 -0

index 7405de2..2b2a1d7 100644

Documentation/ABI/testing/sysfs-devices-memory Users: hotplug memory remove tools · line 64

Quoted 4 lines

Documentation/ABI/testing/sysfs-devices-memory +1 -0

@@ -61,6 +61,14 @@ Users:		hotplug memory remove tools
 		http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
 
 
+What:           /sys/devices/system/memory/memoryX/zones_online_to

I think this name is a bit confusing. How about "valid_online_types"?

Quoted 5 lines

Thanks for your suggestion.

This patch has been added to -mm tree.
If most people think so, i would like to modify the interface name. If not, let's leave it as it is.

Yes, the name could be better. Do we actually need "online" in there? How about "valid_zones"?

Also, it's not really clear to me why we need this sysfs file at all. Do people really read sysfs files, make onlining decisions and manually type in commands? Or is this stuff all automated? If the latter then the script can take care of all this? For example, attempt to online the memory into the desired zone and report failure if that didn't succeed?

IOW, please update the changelog to show

a) example output from /sys/devices/system/memory/memoryX/whatever-we-call-it and

b) example use-cases which help reviewers understand why this feature will be valuable to users.

Also, please do address the error which Yasuaki Ishimatsu identified.

.

Quoted 37 lines · On Mon, 18 Aug 2014 11:25:36 +0800 Zhang Zhen <[email protected]>…

Quoted 36 lines · Toshi Kani

Quoted 28 lines · Zhang Zhen

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

---
 Documentation/ABI/testing/sysfs-devices-memory |  8 ++++
 Documentation/memory-hotplug.txt               |  4 +-
 drivers/base/memory.c                          | 62 ++++++++++++++++++++++++++
 include/linux/memory_hotplug.h                 |  1 +
 mm/memory_hotplug.c                            |  2 +-
 5 files changed, 75 insertions(+), 2 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +0 -0

index 7405de2..2b2a1d7 100644

Documentation/ABI/testing/sysfs-devices-memory Users: hotplug memory remove tools · line 64

Quoted 4 lines

Documentation/ABI/testing/sysfs-devices-memory +1 -0

@@ -61,6 +61,14 @@ Users:		hotplug memory remove tools
 		http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
 
 
+What:           /sys/devices/system/memory/memoryX/zones_online_to

I think this name is a bit confusing. How about "valid_online_types"?

Quoted 5 lines

Thanks for your suggestion.

This patch has been added to -mm tree.
If most people think so, i would like to modify the interface name. If not, let's leave it as it is.

Yes, the name could be better. Do we actually need "online" in there? How about "valid_zones"?

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

---
  Documentation/ABI/testing/sysfs-devices-memory |  8 ++++
  Documentation/memory-hotplug.txt               |  4 +-
  drivers/base/memory.c                          | 62 ++++++++++++++++++++++++++
  include/linux/memory_hotplug.h                 |  1 +
  mm/memory_hotplug.c                            |  2 +-
  5 files changed, 75 insertions(+), 2 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +8 -0

index 7405de2..2b2a1d7 100644
@@ -61,6 +61,14 @@ Users:		hotplug memory remove tools
  		http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
 
 
+What:           /sys/devices/system/memory/memoryX/zones_online_to
+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.
+
  What:		/sys/devices/system/memoryX/nodeY
  Date:		October 2009
  Contact:	Linux Memory Management list <[email protected]>

Documentation/memory-hotplug.txt +3 -1

index 45134dc..5b34e33 100644
@@ -155,6 +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
 
  'phys_index'      : read-only and contains memory block id, same as XXX.
  'state'           : read-write

@@ -170,6 +171,8 @@ 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.
 
  NOTE:
    These directories/files appear after physical memory hotplug phase.

@@ -408,7 +411,6 @@ node if necessary.
    - allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
      sysctl or new control file.
    - showing memory block and physical device relationship.
-  - showing memory block is under ZONE_MOVABLE or not
    - test and make it better memory offlining.
    - support HugeTLB page migration and offlining.
    - memmap removing at memory offline.

drivers/base/memory.c +0 -0

index a2e13e2..b5d693f 100644
@@ -373,10 +373,71 @@ static ssize_t show_phys_device(struct device *dev,
  	return sprintf(buf, "%d\n", mem->phys_device);
  }

drivers/base/memory.c +53 -0

+	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)
+{
+	struct memory_block *mem = to_memory_block(dev);
+	unsigned long start_pfn, end_pfn;
+	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
+	struct page *first_page;
+	struct zone *zone, *zone_prev;
+
+	start_pfn = section_nr_to_pfn(mem->start_section_nr);
+	end_pfn = start_pfn + nr_pages;
+	first_page = pfn_to_page(start_pfn);
+
+	/*The block contains more than one zone can not be offlined.*/
+	if (!test_pages_in_a_zone(start_pfn, end_pfn))
+		return sprintf(buf, "none\n");
+
+	zone = page_zone(first_page);
+
+#ifdef CONFIG_HIGHMEM
+	if (zone_idx(zone) == ZONE_HIGHMEM) {
+		if (__zones_online_to(end_pfn, first_page, nr_pages))
+			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)
+			return sprintf(buf, "%s %s\n",
+						zone->name, (zone - 1)->name);
+	}
+
+	return sprintf(buf, "%s\n", zone->name);
+}
+
  static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
  static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
  static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
  static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
+static DEVICE_ATTR(zones_online_to, 0444, show_zones_online_to, NULL);
 
  /*

* Block size attribute stuff

drivers/base/memory.c +1 -0

@@ -523,6 +584,7 @@ static struct attribute *memory_memblk_attrs[] = {
  	&dev_attr_state.attr,
  	&dev_attr_phys_device.attr,
  	&dev_attr_removable.attr,
+	&dev_attr_zones_online_to.attr,
  	NULL
  };
 

include/linux/memory_hotplug.h +1 -0

index d9524c4..8f1a419 100644
@@ -84,6 +84,7 @@ extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
  extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
  /* VM interface that may be used by firmware interface */
  extern int online_pages(unsigned long, unsigned long, int);
+extern int test_pages_in_a_zone(unsigned long, unsigned long);
  extern void __offline_isolated_pages(unsigned long, unsigned long);
 
  typedef void (*online_page_callback_t)(struct page *page);

mm/memory_hotplug.c +1 -1

index 2ff8c23..29d8693 100644
@@ -1307,7 +1307,7 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
  /*
   * Confirm all pages in a range [start, end) is belongs to the same zone.
   */
-static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
+int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
  {
  	unsigned long pfn;
  	struct zone *zone = NULL;

Quoted 78 lines · Zhang Zhen

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

---
  Documentation/ABI/testing/sysfs-devices-memory |  8 ++++
  Documentation/memory-hotplug.txt               |  4 +-
  drivers/base/memory.c                          | 62 ++++++++++++++++++++++++++
  include/linux/memory_hotplug.h                 |  1 +
  mm/memory_hotplug.c                            |  2 +-
  5 files changed, 75 insertions(+), 2 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +8 -0

index 7405de2..2b2a1d7 100644
@@ -61,6 +61,14 @@ Users:        hotplug memory remove tools
          http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
 
 
+What:           /sys/devices/system/memory/memoryX/zones_online_to
+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.
+
  What:        /sys/devices/system/memoryX/nodeY
  Date:        October 2009
  Contact:    Linux Memory Management list <[email protected]>

Documentation/memory-hotplug.txt +3 -1

index 45134dc..5b34e33 100644
@@ -155,6 +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
 
  'phys_index'      : read-only and contains memory block id, same as XXX.
  'state'           : read-write

@@ -170,6 +171,8 @@ 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.
 
  NOTE:
    These directories/files appear after physical memory hotplug phase.

@@ -408,7 +411,6 @@ node if necessary.
    - allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
      sysctl or new control file.
    - showing memory block and physical device relationship.
-  - showing memory block is under ZONE_MOVABLE or not
    - test and make it better memory offlining.
    - support HugeTLB page migration and offlining.
    - memmap removing at memory offline.

drivers/base/memory.c +0 -0

index a2e13e2..b5d693f 100644
@@ -373,10 +373,71 @@ static ssize_t show_phys_device(struct device *dev,
      return sprintf(buf, "%d\n", mem->phys_device);
  }

drivers/base/memory.c static ssize_t show_phys_device(struct device *dev, · line 384

Quoted 10 lines

drivers/base/memory.c +8 -0

 
+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;

The check is not enough if memory has hole as follows:

PFN 0x00 0xd0 0xe0 0xf0

            +-------------+-------------+-------------+
zone type   |   Normal    |     hole    |   Normal    |
            +-------------+-------------+-------------+

In this case, 0xd1 is invalid pfn. But __zones_online_to should return 0 since 0xe0-0xf0 is Normal zone.

Thanks,
Yasuaki Ishimatsu

Quoted 95 lines

drivers/base/memory.c +53 -0

+    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)
+{
+    struct memory_block *mem = to_memory_block(dev);
+    unsigned long start_pfn, end_pfn;
+    unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
+    struct page *first_page;
+    struct zone *zone, *zone_prev;
+
+    start_pfn = section_nr_to_pfn(mem->start_section_nr);
+    end_pfn = start_pfn + nr_pages;
+    first_page = pfn_to_page(start_pfn);
+
+    /*The block contains more than one zone can not be offlined.*/
+    if (!test_pages_in_a_zone(start_pfn, end_pfn))
+        return sprintf(buf, "none\n");
+
+    zone = page_zone(first_page);
+
+#ifdef CONFIG_HIGHMEM
+    if (zone_idx(zone) == ZONE_HIGHMEM) {
+        if (__zones_online_to(end_pfn, first_page, nr_pages))
+            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)
+            return sprintf(buf, "%s %s\n",
+                        zone->name, (zone - 1)->name);
+    }
+
+    return sprintf(buf, "%s\n", zone->name);
+}
+
  static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
  static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
  static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
  static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
+static DEVICE_ATTR(zones_online_to, 0444, show_zones_online_to, NULL);
 
  /*

* Block size attribute stuff

drivers/base/memory.c +1 -0

@@ -523,6 +584,7 @@ static struct attribute *memory_memblk_attrs[] = {
      &dev_attr_state.attr,
      &dev_attr_phys_device.attr,
      &dev_attr_removable.attr,
+    &dev_attr_zones_online_to.attr,
      NULL
  };
 

include/linux/memory_hotplug.h +1 -0

index d9524c4..8f1a419 100644
@@ -84,6 +84,7 @@ extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
  extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
  /* VM interface that may be used by firmware interface */
  extern int online_pages(unsigned long, unsigned long, int);
+extern int test_pages_in_a_zone(unsigned long, unsigned long);
  extern void __offline_isolated_pages(unsigned long, unsigned long);
 
  typedef void (*online_page_callback_t)(struct page *page);

mm/memory_hotplug.c +1 -1

index 2ff8c23..29d8693 100644
@@ -1307,7 +1307,7 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
  /*
   * Confirm all pages in a range [start, end) is belongs to the same zone.
   */
-static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
+int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
  {
      unsigned long pfn;
      struct zone *zone = NULL;

Signature · 6 lines

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the body to [email protected].  For more info on Linux MM,
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.

Quoted 97 lines · Yasuaki Ishimatsu

Quoted 78 lines · Zhang Zhen

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

---
   Documentation/ABI/testing/sysfs-devices-memory |  8 ++++
   Documentation/memory-hotplug.txt               |  4 +-
   drivers/base/memory.c                          | 62 ++++++++++++++++++++++++++
   include/linux/memory_hotplug.h                 |  1 +
   mm/memory_hotplug.c                            |  2 +-
   5 files changed, 75 insertions(+), 2 deletions(-)

Documentation/ABI/testing/sysfs-devices-memory +8 -0

index 7405de2..2b2a1d7 100644
@@ -61,6 +61,14 @@ Users:        hotplug memory remove tools
           http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
 
 
+What:           /sys/devices/system/memory/memoryX/zones_online_to
+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.
+
   What:        /sys/devices/system/memoryX/nodeY
   Date:        October 2009
   Contact:    Linux Memory Management list <[email protected]>

Documentation/memory-hotplug.txt +3 -1

index 45134dc..5b34e33 100644
@@ -155,6 +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
 
   'phys_index'      : read-only and contains memory block id, same as XXX.
   'state'           : read-write

@@ -170,6 +171,8 @@ 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.
 
   NOTE:
     These directories/files appear after physical memory hotplug phase.

@@ -408,7 +411,6 @@ node if necessary.
     - allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
       sysctl or new control file.
     - showing memory block and physical device relationship.
-  - showing memory block is under ZONE_MOVABLE or not
     - test and make it better memory offlining.
     - support HugeTLB page migration and offlining.
     - memmap removing at memory offline.

drivers/base/memory.c +0 -0

index a2e13e2..b5d693f 100644
@@ -373,10 +373,71 @@ static ssize_t show_phys_device(struct device *dev,
       return sprintf(buf, "%d\n", mem->phys_device);
   }

drivers/base/memory.c static ssize_t show_phys_device(struct device *dev, · line 384

Quoted 10 lines

drivers/base/memory.c +8 -0

 
+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;

The check is not enough if memory has hole as follows:

PFN 0x00 0xd0 0xe0 0xf0

             +-------------+-------------+-------------+
zone type   |   Normal    |     hole    |   Normal    |
             +-------------+-------------+-------------+

Quoted 6 lines

In this case, 0xd1 is invalid pfn. But __zones_online_to should return 0 since 0xe0-0xf0 is Normal zone.

Thanks,
Yasuaki Ishimatsu

You are right, it is not enough.

Here we should make a check as follows.
if ((end_pfn + 1) > zone_end_pfn(page_zone(first_page)))

	return 1;

I will send a patch to fix it.

Thanks !

Quoted 105 lines

Quoted 87 lines

drivers/base/memory.c +53 -0

+    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)
+{
+    struct memory_block *mem = to_memory_block(dev);
+    unsigned long start_pfn, end_pfn;
+    unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
+    struct page *first_page;
+    struct zone *zone, *zone_prev;
+
+    start_pfn = section_nr_to_pfn(mem->start_section_nr);
+    end_pfn = start_pfn + nr_pages;
+    first_page = pfn_to_page(start_pfn);
+
+    /*The block contains more than one zone can not be offlined.*/
+    if (!test_pages_in_a_zone(start_pfn, end_pfn))
+        return sprintf(buf, "none\n");
+
+    zone = page_zone(first_page);
+
+#ifdef CONFIG_HIGHMEM
+    if (zone_idx(zone) == ZONE_HIGHMEM) {
+        if (__zones_online_to(end_pfn, first_page, nr_pages))
+            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)
+            return sprintf(buf, "%s %s\n",
+                        zone->name, (zone - 1)->name);
+    }
+
+    return sprintf(buf, "%s\n", zone->name);
+}
+
   static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
   static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
   static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
   static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
+static DEVICE_ATTR(zones_online_to, 0444, show_zones_online_to, NULL);
 
   /*

* Block size attribute stuff

drivers/base/memory.c +1 -0

@@ -523,6 +584,7 @@ static struct attribute *memory_memblk_attrs[] = {
       &dev_attr_state.attr,
       &dev_attr_phys_device.attr,
       &dev_attr_removable.attr,
+    &dev_attr_zones_online_to.attr,
       NULL
   };
 

include/linux/memory_hotplug.h +1 -0

index d9524c4..8f1a419 100644
@@ -84,6 +84,7 @@ extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
   extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
   /* VM interface that may be used by firmware interface */
   extern int online_pages(unsigned long, unsigned long, int);
+extern int test_pages_in_a_zone(unsigned long, unsigned long);
   extern void __offline_isolated_pages(unsigned long, unsigned long);
 
   typedef void (*online_page_callback_t)(struct page *page);

mm/memory_hotplug.c +0 -0

index 2ff8c23..29d8693 100644

mm/memory_hotplug.c int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages) · line 1313

Quoted 8 lines

mm/memory_hotplug.c +1 -1

@@ -1307,7 +1307,7 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
   /*
    * Confirm all pages in a range [start, end) is belongs to the same zone.
    */
-static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
+int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
   {
       unsigned long pfn;
       struct zone *zone = NULL;

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

.

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

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

Quoted 14 lines · Zhang Zhen

Currently memory-hotplug has two limits:
1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to which zone, and don't need to know the above two limits.

Updated the related Documentation.

Change v1 -> v2:
- optimize the implementation following Dave Hansen's suggestion

Quoted 1 line

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

linux-next build failure:

drivers/built-in.o: In function `show_zones_online_to':
memory.c:(.text+0x13ee09): undefined reference to `test_pages_in_a_zone'