mm: add numa node symlink for memory section in sysfs
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.
Signed-off-by: Alex Chiang <achiang@hp.com>
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>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 @@
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 @@
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 @@
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 54e5d8e..44eed11 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -312,6 +312,7 @@
/* 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)
@@ -328,9 +329,15 @@
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;
@@ -359,6 +366,8 @@
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;
}