[PATCH v3 0/5]

[PATCH v3 0/5]

[Alex Chiang]

This is v3 of the series.

I based it off of Linus's latest tree. 

I did not include David Rientjes's "mm: slab allocate memory section nodemask
for large systems" patch in my series, since it's not necessarily related.

Please consider for inclusion for the next merge window (v2.6.33).

Thanks,
/ac

v2 -> v3:
	- rebased to Linus's latest tree (799dd75b)
	- Added David Rientjes's Acked-by: flags
	- dropped S390 cc's, since they are unaffected by this series

v1 -> v2: http://thread.gmane.org/gmane.linux.kernel.mm/40084/
        Address David Rientjes's comments
        - check return value of sysfs_create_link in register_cpu_under_node
        - do /not/ convert [un]register_cpu_under_node to return void, since
          sparse starts whinging if you ignore sysfs_create_link()'s return
          value and working around sparse makes the code ugly
        - adjust documentation

        Added S390 maintainers to cc: for patch [1/5] as per Kame-san's
        suggestion. S390 may map a memory section to more than one node,
        causing this series to break.


---

Alex Chiang (5):
      mm: add numa node symlink for memory section in sysfs
      mm: refactor register_cpu_under_node()
      mm: refactor unregister_cpu_under_node()
      mm: add numa node symlink for cpu devices in sysfs
      Documentation: ABI: /sys/devices/system/cpu/cpu#/node


 Documentation/ABI/testing/sysfs-devices-memory     |   14 ++++-
 Documentation/ABI/testing/sysfs-devices-system-cpu |   14 +++++
 Documentation/memory-hotplug.txt                   |   11 ++--
 drivers/base/node.c                                |   58 ++++++++++++++------
 4 files changed, 76 insertions(+), 21 deletions(-)

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[PATCH v3 1/5] mm: add numa node symlink for memory section in sysfs

[Alex Chiang]

Commit c04fc586c (mm: show node to memory section relationship with
symlinks in sysfs) created symlinks from nodes to memory sections, e.g.

/sys/devices/system/node/node1/memory135 -> ../../memory/memory135

If you're examining the memory section though and are wondering what
node it might belong to, you can find it by grovelling around in
sysfs, but it's a little cumbersome.

Add a reverse symlink for each memory section that points back to the
node to which it belongs.

Cc: Gary Hade <garyhade@us.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
---

 Documentation/ABI/testing/sysfs-devices-memory |   14 +++++++++++++-
 Documentation/memory-hotplug.txt               |   11 +++++++----
 drivers/base/node.c                            |   11 ++++++++++-
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory
index 9fe91c0..bf1627b 100644
--- a/Documentation/ABI/testing/sysfs-devices-memory
+++ b/Documentation/ABI/testing/sysfs-devices-memory
@@ -60,6 +60,19 @@ Description:
 Users:		hotplug memory remove tools
 		https://w3.opensource.ibm.com/projects/powerpc-utils/
 
+
+What:		/sys/devices/system/memoryX/nodeY
+Date:		October 2009
+Contact:	Linux Memory Management list <linux-mm@kvack.org>
+Description:
+		When CONFIG_NUMA is enabled, a symbolic link that
+		points to the corresponding NUMA node directory.
+
+		For example, the following symbolic link is created for
+		memory section 9 on node0:
+		/sys/devices/system/memory/memory9/node0 -> ../../node/node0
+
+
 What:		/sys/devices/system/node/nodeX/memoryY
 Date:		September 2008
 Contact:	Gary Hade <garyhade@us.ibm.com>
@@ -70,4 +83,3 @@ Description:
 		memory section directory.  For example, the following symbolic
 		link is created for memory section 9 on node0.
 		/sys/devices/system/node/node0/memory9 -> ../../memory/memory9
-
diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt
index bbc8a6a..57e7e9c 100644
--- a/Documentation/memory-hotplug.txt
+++ b/Documentation/memory-hotplug.txt
@@ -160,12 +160,15 @@ Under each section, you can see 4 files.
 NOTE:
   These directories/files appear after physical memory hotplug phase.
 
-If CONFIG_NUMA is enabled the
-/sys/devices/system/memory/memoryXXX memory section
-directories can also be accessed via symbolic links located in
-the /sys/devices/system/node/node* directories.  For example:
+If CONFIG_NUMA is enabled the memoryXXX/ directories can also be accessed
+via symbolic links located in the /sys/devices/system/node/node* directories.
+
+For example:
 /sys/devices/system/node/node0/memory9 -> ../../memory/memory9
 
+A backlink will also be created:
+/sys/devices/system/memory/memory9/node0 -> ../../node/node0
+
 --------------------------------
 4. Physical memory hot-add phase
 --------------------------------
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 1fe5536..3108b21 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -268,6 +268,7 @@ static int get_nid_for_pfn(unsigned long pfn)
 /* register memory section under specified node if it spans that node */
 int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
 {
+	int ret;
 	unsigned long pfn, sect_start_pfn, sect_end_pfn;
 
 	if (!mem_blk)
@@ -284,9 +285,15 @@ int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
 			continue;
 		if (page_nid != nid)
 			continue;
-		return sysfs_create_link_nowarn(&node_devices[nid].sysdev.kobj,
+		ret = sysfs_create_link_nowarn(&node_devices[nid].sysdev.kobj,
 					&mem_blk->sysdev.kobj,
 					kobject_name(&mem_blk->sysdev.kobj));
+		if (ret)
+			return ret;
+
+		return sysfs_create_link_nowarn(&mem_blk->sysdev.kobj,
+				&node_devices[nid].sysdev.kobj,
+				kobject_name(&node_devices[nid].sysdev.kobj));
 	}
 	/* mem section does not span the specified node */
 	return 0;
@@ -315,6 +322,8 @@ int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
 			continue;
 		sysfs_remove_link(&node_devices[nid].sysdev.kobj,
 			 kobject_name(&mem_blk->sysdev.kobj));
+		sysfs_remove_link(&mem_blk->sysdev.kobj,
+			 kobject_name(&node_devices[nid].sysdev.kobj));
 	}
 	return 0;
 }

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Re: [PATCH v3 1/5] mm: add numa node symlink for memory section in sysfs

[Gary Hade]

On Tue, Nov 10, 2009 at 03:36:44PM -0700, Alex Chiang wrote:
> Commit c04fc586c (mm: show node to memory section relationship with
> symlinks in sysfs) created symlinks from nodes to memory sections, e.g.
> 
> /sys/devices/system/node/node1/memory135 -> ../../memory/memory135
> 
> If you're examining the memory section though and are wondering what
> node it might belong to, you can find it by grovelling around in
> sysfs, but it's a little cumbersome.
> 
> Add a reverse symlink for each memory section that points back to the
> node to which it belongs.

Hi Alex,
I'm kinda late to the party but I finally had a chance to review
and try it out on one of our systems today.  Looks good to me.
Tested-by: Gary Hade <garyhade@us.ibm.com>
Acked-by: Gary Hade <garyhade@us.ibm.com>

Gary

-- 
Gary Hade
System x Enablement
IBM Linux Technology Center
503-578-4503  IBM T/L: 775-4503
garyhade@us.ibm.com
http://www.ibm.com/linux/ltc

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[PATCH v3 2/5] mm: refactor register_cpu_under_node()

[Alex Chiang]

By returning early if the node is not online, we can unindent the
interesting code by one level.

No functional change.

Signed-off-by: Alex Chiang <achiang@hp.com>
---

 drivers/base/node.c |   20 +++++++++++---------
 1 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 3108b21..ef7dd22 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -227,16 +227,18 @@ struct node node_devices[MAX_NUMNODES];
  */
 int register_cpu_under_node(unsigned int cpu, unsigned int nid)
 {
-	if (node_online(nid)) {
-		struct sys_device *obj = get_cpu_sysdev(cpu);
-		if (!obj)
-			return 0;
-		return sysfs_create_link(&node_devices[nid].sysdev.kobj,
-					 &obj->kobj,
-					 kobject_name(&obj->kobj));
-	 }
+	struct sys_device *obj;
 
-	return 0;
+	if (!node_online(nid))
+		return 0;
+
+	obj = get_cpu_sysdev(cpu);
+	if (!obj)
+		return 0;
+
+	return sysfs_create_link(&node_devices[nid].sysdev.kobj,
+				&obj->kobj,
+				kobject_name(&obj->kobj));
 }
 
 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)

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[PATCH v3 3/5] mm: refactor unregister_cpu_under_node()

[Alex Chiang]

By returning early if the node is not online, we can unindent the
interesting code by two levels.

No functional change.

Signed-off-by: Alex Chiang <achiang@hp.com>
---

 drivers/base/node.c |   18 ++++++++++++------
 1 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index ef7dd22..ffda067 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -243,12 +243,18 @@ int register_cpu_under_node(unsigned int cpu, unsigned int nid)
 
 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
 {
-	if (node_online(nid)) {
-		struct sys_device *obj = get_cpu_sysdev(cpu);
-		if (obj)
-			sysfs_remove_link(&node_devices[nid].sysdev.kobj,
-					 kobject_name(&obj->kobj));
-	}
+	struct sys_device *obj;
+
+	if (!node_online(nid))
+		return 0;
+
+	obj = get_cpu_sysdev(cpu);
+	if (!obj)
+		return 0;
+
+	sysfs_remove_link(&node_devices[nid].sysdev.kobj,
+			  kobject_name(&obj->kobj));
+
 	return 0;
 }
 

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[PATCH v3 4/5] mm: add numa node symlink for cpu devices in sysfs

[Alex Chiang]

You can discover which CPUs belong to a NUMA node by examining
/sys/devices/system/node/node#/

However, it's not convenient to go in the other direction, when looking at
/sys/devices/system/cpu/cpu#/

Yes, you can muck about in sysfs, but adding these symlinks makes
life a lot more convenient.

Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
---

 drivers/base/node.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index ffda067..24fa962 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -227,6 +227,7 @@ struct node node_devices[MAX_NUMNODES];
  */
 int register_cpu_under_node(unsigned int cpu, unsigned int nid)
 {
+	int ret;
 	struct sys_device *obj;
 
 	if (!node_online(nid))
@@ -236,9 +237,15 @@ int register_cpu_under_node(unsigned int cpu, unsigned int nid)
 	if (!obj)
 		return 0;
 
-	return sysfs_create_link(&node_devices[nid].sysdev.kobj,
+	ret = sysfs_create_link(&node_devices[nid].sysdev.kobj,
 				&obj->kobj,
 				kobject_name(&obj->kobj));
+	if (ret)
+		return ret;
+
+	return sysfs_create_link(&obj->kobj,
+				 &node_devices[nid].sysdev.kobj,
+				 kobject_name(&node_devices[nid].sysdev.kobj));
 }
 
 int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
@@ -254,6 +261,8 @@ int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
 
 	sysfs_remove_link(&node_devices[nid].sysdev.kobj,
 			  kobject_name(&obj->kobj));
+	sysfs_remove_link(&obj->kobj,
+			  kobject_name(&node_devices[nid].sysdev.kobj));
 
 	return 0;
 }

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[PATCH v3 5/5] Documentation: ABI: /sys/devices/system/cpu/cpu#/node

[Alex Chiang]

Describe NUMA node symlink created for CPUs when CONFIG_NUMA is set.

Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
---

 Documentation/ABI/testing/sysfs-devices-system-cpu |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 5aace16..1671634 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -94,6 +94,20 @@ Description:	Discover and change the online state of a CPU.
 		For more information, please read Documentation/cpu-hotplug.txt
 
 
+What:		/sys/devices/system/cpu/cpu#/node
+Date:		October 2009
+Contact:	Linux memory management mailing list <linux-mm@kvack.org>
+Description:	Discover NUMA node a CPU belongs to
+
+		When CONFIG_NUMA is enabled, a symbolic link that points
+		to the corresponding NUMA node directory.
+
+		For example, the following symlink is created for cpu42
+		in NUMA node 2:
+
+		/sys/devices/system/cpu/cpu42/node2 -> ../../node/node2
+
+
 What:		/sys/devices/system/cpu/cpu#/topology/core_id
 		/sys/devices/system/cpu/cpu#/topology/core_siblings
 		/sys/devices/system/cpu/cpu#/topology/core_siblings_list

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