mm: show node to memory section relationship with symlinks in sysfs
Show node to memory section relationship with symlinks in sysfs
Add /sys/devices/system/node/nodeX/memoryY symlinks for all
the memory sections located on nodeX. For example:
/sys/devices/system/node/node1/memory135 -> ../../memory/memory135
indicates that memory section 135 resides on node1.
Also revises documentation to cover this change as well as updating
Documentation/ABI/testing/sysfs-devices-memory to include descriptions
of memory hotremove files 'phys_device', 'phys_index', and 'state'
that were previously not described there.
In addition to it always being a good policy to provide users with
the maximum possible amount of physical location information for
resources that can be hot-added and/or hot-removed, the following
are some (but likely not all) of the user benefits provided by
this change.
Immediate:
- Provides information needed to determine the specific node
on which a defective DIMM is located. This will reduce system
downtime when the node or defective DIMM is swapped out.
- Prevents unintended onlining of a memory section that was
previously offlined due to a defective DIMM. This could happen
during node hot-add when the user or node hot-add assist script
onlines _all_ offlined sections due to user or script inability
to identify the specific memory sections located on the hot-added
node. The consequences of reintroducing the defective memory
could be ugly.
- Provides information needed to vary the amount and distribution
of memory on specific nodes for testing or debugging purposes.
Future:
- Will provide information needed to identify the memory
sections that need to be offlined prior to physical removal
of a specific node.
Symlink creation during boot was tested on 2-node x86_64, 2-node
ppc64, and 2-node ia64 systems. Symlink creation during physical
memory hot-add tested on a 2-node x86_64 system.
Signed-off-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 5260e9e..989429c 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -347,8 +347,9 @@
* section belongs to...
*/
-static int add_memory_block(unsigned long node_id, struct mem_section *section,
- unsigned long state, int phys_device)
+static int add_memory_block(int nid, struct mem_section *section,
+ unsigned long state, int phys_device,
+ enum mem_add_context context)
{
struct memory_block *mem = kzalloc(sizeof(*mem), GFP_KERNEL);
int ret = 0;
@@ -370,6 +371,10 @@
ret = mem_create_simple_file(mem, phys_device);
if (!ret)
ret = mem_create_simple_file(mem, removable);
+ if (!ret) {
+ if (context == HOTPLUG)
+ ret = register_mem_sect_under_node(mem, nid);
+ }
return ret;
}
@@ -382,7 +387,7 @@
*
* This could be made generic for all sysdev classes.
*/
-static struct memory_block *find_memory_block(struct mem_section *section)
+struct memory_block *find_memory_block(struct mem_section *section)
{
struct kobject *kobj;
struct sys_device *sysdev;
@@ -411,6 +416,7 @@
struct memory_block *mem;
mem = find_memory_block(section);
+ unregister_mem_sect_under_nodes(mem);
mem_remove_simple_file(mem, phys_index);
mem_remove_simple_file(mem, state);
mem_remove_simple_file(mem, phys_device);
@@ -424,9 +430,9 @@
* need an interface for the VM to add new memory regions,
* but without onlining it.
*/
-int register_new_memory(struct mem_section *section)
+int register_new_memory(int nid, struct mem_section *section)
{
- return add_memory_block(0, section, MEM_OFFLINE, 0);
+ return add_memory_block(nid, section, MEM_OFFLINE, 0, HOTPLUG);
}
int unregister_memory_section(struct mem_section *section)
@@ -458,7 +464,8 @@
for (i = 0; i < NR_MEM_SECTIONS; i++) {
if (!present_section_nr(i))
continue;
- err = add_memory_block(0, __nr_to_section(i), MEM_ONLINE, 0);
+ err = add_memory_block(0, __nr_to_section(i), MEM_ONLINE,
+ 0, BOOT);
if (!ret)
ret = err;
}