[PATCH 1/2] [REPOST] mm: show node to memory section relationship with symlinks in sysfs

Gary Hade
2008-10-09T19:20:52Z

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.

Tested on 2-node x86_64, 2-node ppc64, and 2-node ia64 systems.

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.

Supersedes the "mm: show memory section to node relationship in sysfs"
patch posted on 05 Sept 2008 which created node ID containing 'node'
files in /sys/devices/system/memory/memoryX instead of symlinks.
Changed from files to symlinks due to feedback that symlinks were
more consistent with the sysfs way.

Also supercedes the "mm: show node to memory section relationship
with symlinks in sysfs" patch posted on 29 Sept 2008 to address a
Yasunori Goto reported problem where an incorrect symlink was created
due to a range of uninitialized pages at the beginning of a section.
This problem which produced a symlink in /sys/devices/system/node/node0
that incorrectly referenced a mem section located on node1 is corrected
in this version. This version also covers the case were a mem section
could span multiple nodes.

Signed-off-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>

---
Documentation/ABI/testing/sysfs-devices-memory | 51 +++++++
Documentation/memory-hotplug.txt | 16 +-
arch/ia64/mm/init.c | 2
arch/powerpc/mm/mem.c | 2
arch/s390/mm/init.c | 2
arch/sh/mm/init.c | 3
arch/x86/mm/init_32.c | 2
arch/x86/mm/init_64.c | 2
drivers/base/memory.c | 19 +-
drivers/base/node.c | 100 +++++++++++++++
include/linux/memory.h | 6
include/linux/memory_hotplug.h | 2
include/linux/node.h | 13 +
mm/memory_hotplug.c | 9 -
14 files changed, 205 insertions(+), 24 deletions(-)

Index: linux-2.6.27-rc8/Documentation/ABI/testing/sysfs-devices-memory
===================================================================
--- linux-2.6.27-rc8.orig/Documentation/ABI/testing/sysfs-devices-memory 2008-10-06 11:18:46.000000000 -0700
+++ linux-2.6.27-rc8/Documentation/ABI/testing/sysfs-devices-memory 2008-10-06 11:20:19.000000000 -0700
@@ -6,7 +6,6 @@
internal state of the kernel memory blocks. Files could be
added or removed dynamically to represent hot-add/remove
operations.
-
Users: hotplug memory add/remove tools
https://w3.opensource.ibm.com/projects/powerpc-utils/

@@ -19,6 +18,56 @@
This is useful for a user-level agent to determine
identify removable sections of the memory before attempting
potentially expensive hot-remove memory operation
+Users: hotplug memory remove tools
+ https://w3.opensource.ibm.com/projects/powerpc-utils/
+
+What: /sys/devices/system/memory/memoryX/phys_device
+Date: September 2008
+Contact: Badari Pulavarty <pbadari@us.ibm.com>
+Description:
+ The file /sys/devices/system/memory/memoryX/phys_device
+ is read-only and is designed to show the name of physical
+ memory device. Implementation is currently incomplete.

+What: /sys/devices/system/memory/memoryX/phys_index
+Date: September 2008
+Contact: Badari Pulavarty <pbadari@us.ibm.com>
+Description:
+ The file /sys/devices/system/memory/memoryX/phys_index
+ is read-only and contains the section ID in hexadecimal
+ which is equivalent to decimal X contained in the
+ memory section directory name.
+
+What: /sys/devices/system/memory/memoryX/state
+Date: September 2008
+Contact: Badari Pulavarty <pbadari@us.ibm.com>
+Description:
+ The file /sys/devices/system/memory/memoryX/state
+ is read-write. When read, it's contents show the
+ online/offline state of the memory section. When written,
+ root can toggle the the online/offline state of a removable
+ memory section (see removable file description above)
+ using the following commands.
+ # echo online > /sys/devices/system/memory/memoryX/state
+ # echo offline > /sys/devices/system/memory/memoryX/state
+
+ For example, if /sys/devices/system/memory/memory22/removable
+ contains a value of 1 and
+ /sys/devices/system/memory/memory22/state contains the
+ string "online" the following command can be executed by
+ by root to offline that section.
+ # echo offline > /sys/devices/system/memory/memory22/state
Users: hotplug memory remove tools
https://w3.opensource.ibm.com/projects/powerpc-utils/
+
+What: /sys/devices/system/node/nodeX/memoryY
+Date: September 2008
+Contact: Gary Hade <garyhade@us.ibm.com>
+Description:
+ When CONFIG_NUMA is enabled
+ /sys/devices/system/node/nodeX/memoryY is a symbolic link that
+ points to the corresponding /sys/devices/system/memory/memoryY
+ 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
+
Index: linux-2.6.27-rc8/Documentation/memory-hotplug.txt
===================================================================
--- linux-2.6.27-rc8.orig/Documentation/memory-hotplug.txt 2008-10-06 11:18:45.000000000 -0700
+++ linux-2.6.27-rc8/Documentation/memory-hotplug.txt 2008-10-06 11:20:42.000000000 -0700
@@ -124,7 +124,7 @@
This option can be kernel module too.

--------------------------------
-3 sysfs files for memory hotplug
+4 sysfs files for memory hotplug
--------------------------------
All sections have their device information under /sys/devices/system/memory as

@@ -138,11 +138,12 @@
(0x100000000 / 1Gib = 4)
This device covers address range [0x100000000 ... 0x140000000)

-Under each section, you can see 3 files.
+Under each section, you can see 4 files.

/sys/devices/system/memory/memoryXXX/phys_index
/sys/devices/system/memory/memoryXXX/phys_device
/sys/devices/system/memory/memoryXXX/state
+/sys/devices/system/memory/memoryXXX/removable

'phys_index' : read-only and contains section id, same as XXX.
'state' : read-write
@@ -150,10 +151,20 @@
at write: user can specify "online", "offline" command
'phys_device': read-only: designed to show the name of physical memory device.
This is not well implemented now.
+'removable' : read-only: contains an integer value indicating
+ whether the memory section is removable or not
+ removable. A value of 1 indicates that the memory
+ section is removable and a value of 0 indicates that
+ it is not removable.

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:
+/sys/devices/system/node/node0/memory9 -> ../../memory/memory9

--------------------------------
4. Physical memory hot-add phase
@@ -365,7 +376,6 @@
- allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
sysctl or new control file.
- showing memory section and physical device relationship.
- - showing memory section and node relationship (maybe good for NUMA)
- showing memory section is under ZONE_MOVABLE or not
- test and make it better memory offlining.
- support HugeTLB page migration and offlining.
Index: linux-2.6.27-rc8/arch/ia64/mm/init.c
===================================================================
--- linux-2.6.27-rc8.orig/arch/ia64/mm/init.c 2008-10-06 11:18:45.000000000 -0700
+++ linux-2.6.27-rc8/arch/ia64/mm/init.c 2008-10-06 11:19:41.000000000 -0700
@@ -693,7 +693,7 @@
pgdat = NODE_DATA(nid);

zone = pgdat->node_zones + ZONE_NORMAL;
- ret = __add_pages(zone, start_pfn, nr_pages);
+ ret = __add_pages(nid, zone, start_pfn, nr_pages);

if (ret)
printk("%s: Problem encountered in __add_pages() as ret=%d\n",
Index: linux-2.6.27-rc8/arch/powerpc/mm/mem.c
===================================================================
--- linux-2.6.27-rc8.orig/arch/powerpc/mm/mem.c 2008-10-06 11:18:44.000000000 -0700
+++ linux-2.6.27-rc8/arch/powerpc/mm/mem.c 2008-10-06 11:19:41.000000000 -0700
@@ -133,7 +133,7 @@
/* this should work for most non-highmem platforms */
zone = pgdata->node_zones;

- return __add_pages(zone, start_pfn, nr_pages);
+ return __add_pages(nid, zone, start_pfn, nr_pages);
}

#ifdef CONFIG_MEMORY_HOTREMOVE
Index: linux-2.6.27-rc8/arch/s390/mm/init.c
===================================================================
--- linux-2.6.27-rc8.orig/arch/s390/mm/init.c 2008-10-06 11:18:45.000000000 -0700
+++ linux-2.6.27-rc8/arch/s390/mm/init.c 2008-10-06 11:19:41.000000000 -0700
@@ -183,7 +183,7 @@
rc = vmem_add_mapping(start, size);
if (rc)
return rc;
- rc = __add_pages(zone, PFN_DOWN(start), PFN_DOWN(size));
+ rc = __add_pages(nid, zone, PFN_DOWN(start), PFN_DOWN(size));
if (rc)
vmem_remove_mapping(start, size);
return rc;
Index: linux-2.6.27-rc8/arch/sh/mm/init.c
===================================================================
--- linux-2.6.27-rc8.orig/arch/sh/mm/init.c 2008-10-06 11:18:45.000000000 -0700
+++ linux-2.6.27-rc8/arch/sh/mm/init.c 2008-10-06 11:19:41.000000000 -0700
@@ -276,7 +276,8 @@
pgdat = NODE_DATA(nid);

/* We only have ZONE_NORMAL, so this is easy.. */
- ret = __add_pages(pgdat->node_zones + ZONE_NORMAL, start_pfn, nr_pages);
+ ret = __add_pages(nid, pgdat->node_zones + ZONE_NORMAL,
+ start_pfn, nr_pages);
if (unlikely(ret))
printk("%s: Failed, __add_pages() == %d\n", __func__, ret);

Index: linux-2.6.27-rc8/arch/x86/mm/init_32.c
===================================================================
--- linux-2.6.27-rc8.orig/arch/x86/mm/init_32.c 2008-10-06 11:18:45.000000000 -0700
+++ linux-2.6.27-rc8/arch/x86/mm/init_32.c 2008-10-06 11:19:41.000000000 -0700
@@ -995,7 +995,7 @@
unsigned long start_pfn = start >> PAGE_SHIFT;
unsigned long nr_pages = size >> PAGE_SHIFT;

- return __add_pages(zone, start_pfn, nr_pages);
+ return __add_pages(nid, zone, start_pfn, nr_pages);
}
#endif

Index: linux-2.6.27-rc8/drivers/base/memory.c
===================================================================
--- linux-2.6.27-rc8.orig/drivers/base/memory.c 2008-10-06 11:18:44.000000000 -0700
+++ linux-2.6.27-rc8/drivers/base/memory.c 2008-10-06 11:19:41.000000000 -0700
@@ -345,8 +345,9 @@
* 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;
@@ -368,6 +369,10 @@
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;
}
@@ -380,7 +385,7 @@
*
* 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;
@@ -409,6 +414,7 @@
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);
@@ -422,9 +428,9 @@
* 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)
@@ -456,7 +462,8 @@
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;
}
Index: linux-2.6.27-rc8/drivers/base/node.c
===================================================================
--- linux-2.6.27-rc8.orig/drivers/base/node.c 2008-10-06 11:18:44.000000000 -0700
+++ linux-2.6.27-rc8/drivers/base/node.c 2008-10-06 11:19:41.000000000 -0700
@@ -6,6 +6,7 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
+#include <linux/memory.h>
#include <linux/node.h>
#include <linux/hugetlb.h>
#include <linux/cpumask.h>
@@ -225,6 +226,102 @@
return 0;
}

+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
+#define page_initialized(page) (page->lru.next)
+
+static int get_nid_for_pfn(unsigned long pfn)
+{
+ struct page *page;
+
+ if (!pfn_valid_within(pfn))
+ return -1;
+ page = pfn_to_page(pfn);
+ if (!page_initialized(page))
+ return -1;
+ return pfn_to_nid(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)
+{
+ unsigned long pfn, sect_start_pfn, sect_end_pfn;
+
+ if (!mem_blk)
+ return -EFAULT;
+ if (!node_online(nid))
+ return 0;
+ sect_start_pfn = section_nr_to_pfn(mem_blk->phys_index);
+ sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
+ for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
+ int page_nid;
+
+ page_nid = get_nid_for_pfn(pfn);
+ if (page_nid < 0)
+ continue;
+ if (page_nid != nid)
+ continue;
+ return sysfs_create_link_nowarn(&node_devices[nid].sysdev.kobj,
+ &mem_blk->sysdev.kobj,
+ kobject_name(&mem_blk->sysdev.kobj));
+ }
+ /* mem section does not span the specified node */
+ return 0;
+}
+
+/* unregister memory section under all nodes that it spans */
+int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
+{
+ nodemask_t unlinked_nodes;
+ unsigned long pfn, sect_start_pfn, sect_end_pfn;
+
+ if (!mem_blk)
+ return -EFAULT;
+ nodes_clear(unlinked_nodes);
+ sect_start_pfn = section_nr_to_pfn(mem_blk->phys_index);
+ sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
+ for (pfn = sect_start_pfn; pfn < sect_end_pfn; pfn++) {
+ unsigned int nid;
+
+ nid = get_nid_for_pfn(pfn);
+ if (nid < 0)
+ continue;
+ if (!node_online(nid))
+ continue;
+ if (node_test_and_set(nid, unlinked_nodes))
+ continue;
+ sysfs_remove_link(&node_devices[nid].sysdev.kobj,
+ kobject_name(&mem_blk->sysdev.kobj));
+ }
+ return 0;
+}
+
+static int link_mem_sections(int nid)
+{
+ unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
+ unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
+ unsigned long pfn;
+ int err = 0;
+
+ for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ unsigned long section_nr = pfn_to_section_nr(pfn);
+ struct mem_section *mem_sect;
+ struct memory_block *mem_blk;
+ int ret;
+
+ if (!present_section_nr(section_nr))
+ continue;
+ mem_sect = __nr_to_section(section_nr);
+ mem_blk = find_memory_block(mem_sect);
+ ret = register_mem_sect_under_node(mem_blk, nid);
+ if (!err)
+ err = ret;
+ }
+ return err;
+}
+#else
+static int link_mem_sections(int nid) { return 0; }
+#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
+
int register_one_node(int nid)
{
int error = 0;
@@ -244,6 +341,9 @@
if (cpu_to_node(cpu) == nid)
register_cpu_under_node(cpu, nid);
}
+
+ /* link memory sections under this node */
+ error = link_mem_sections(nid);
}

return error;
Index: linux-2.6.27-rc8/include/linux/memory.h
===================================================================
--- linux-2.6.27-rc8.orig/include/linux/memory.h 2008-10-06 11:18:44.000000000 -0700
+++ linux-2.6.27-rc8/include/linux/memory.h 2008-10-06 11:19:41.000000000 -0700
@@ -79,14 +79,14 @@
#else
extern int register_memory_notifier(struct notifier_block *nb);
extern void unregister_memory_notifier(struct notifier_block *nb);
-extern int register_new_memory(struct mem_section *);
+extern int register_new_memory(int, struct mem_section *);
extern int unregister_memory_section(struct mem_section *);
extern int memory_dev_init(void);
extern int remove_memory_block(unsigned long, struct mem_section *, int);
extern int memory_notify(unsigned long val, void *v);
+extern struct memory_block *find_memory_block(struct mem_section *);
#define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<<PAGE_SHIFT)
-
-
+enum mem_add_context { BOOT, HOTPLUG };
#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */

#ifdef CONFIG_MEMORY_HOTPLUG
Index: linux-2.6.27-rc8/include/linux/memory_hotplug.h
===================================================================
--- linux-2.6.27-rc8.orig/include/linux/memory_hotplug.h 2008-10-06 11:18:44.000000000 -0700
+++ linux-2.6.27-rc8/include/linux/memory_hotplug.h 2008-10-06 11:19:41.000000000 -0700
@@ -72,7 +72,7 @@
extern int offline_pages(unsigned long, unsigned long, unsigned long);

/* reasonably generic interface to expand the physical pages in a zone */
-extern int __add_pages(struct zone *zone, unsigned long start_pfn,
+extern int __add_pages(int nid, struct zone *zone, unsigned long start_pfn,
unsigned long nr_pages);
extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
unsigned long nr_pages);
Index: linux-2.6.27-rc8/include/linux/node.h
===================================================================
--- linux-2.6.27-rc8.orig/include/linux/node.h 2008-10-06 11:18:44.000000000 -0700
+++ linux-2.6.27-rc8/include/linux/node.h 2008-10-06 11:19:41.000000000 -0700
@@ -26,6 +26,7 @@
struct sys_device sysdev;
};

+struct memory_block;
extern struct node node_devices[];

extern int register_node(struct node *, int, struct node *);
@@ -35,6 +36,9 @@
extern void unregister_one_node(int nid);
extern int register_cpu_under_node(unsigned int cpu, unsigned int nid);
extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
+extern int register_mem_sect_under_node(struct memory_block *mem_blk,
+ int nid);
+extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk);
#else
static inline int register_one_node(int nid)
{
@@ -52,6 +56,15 @@
{
return 0;
}
+static inline int register_mem_sect_under_node(struct memory_block *mem_blk,
+ int nid)
+{
+ return 0;
+}
+static inline int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
+{
+ return 0;
+}
#endif

#define to_node(sys_device) container_of(sys_device, struct node, sysdev)
Index: linux-2.6.27-rc8/mm/memory_hotplug.c
===================================================================
--- linux-2.6.27-rc8.orig/mm/memory_hotplug.c 2008-10-06 11:18:44.000000000 -0700
+++ linux-2.6.27-rc8/mm/memory_hotplug.c 2008-10-06 11:19:41.000000000 -0700
@@ -216,7 +216,8 @@
return 0;
}

-static int __add_section(struct zone *zone, unsigned long phys_start_pfn)
+static int __add_section(int nid, struct zone *zone,
+ unsigned long phys_start_pfn)
{
int nr_pages = PAGES_PER_SECTION;
int ret;
@@ -234,7 +235,7 @@
if (ret < 0)
return ret;

- return register_new_memory(__pfn_to_section(phys_start_pfn));
+ return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP
@@ -273,7 +274,7 @@
* call this function after deciding the zone to which to
* add the new pages.
*/
-int __add_pages(struct zone *zone, unsigned long phys_start_pfn,
+int __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
unsigned long nr_pages)
{
unsigned long i;
@@ -284,7 +285,7 @@
end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);

for (i = start_sec; i <= end_sec; i++) {
- err = __add_section(zone, i << PFN_SECTION_SHIFT);
+ err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);

/*
* EEXIST is finally dealt with by ioresource collision
Index: linux-2.6.27-rc8/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.27-rc8.orig/arch/x86/mm/init_64.c 2008-10-06 11:18:45.000000000 -0700
+++ linux-2.6.27-rc8/arch/x86/mm/init_64.c 2008-10-06 11:24:09.000000000 -0700
@@ -725,7 +725,7 @@
if (last_mapped_pfn > max_pfn_mapped)
max_pfn_mapped = last_mapped_pfn;

- ret = __add_pages(zone, start_pfn, nr_pages);
+ ret = __add_pages(nid, zone, start_pfn, nr_pages);
WARN_ON(1);

return ret;