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/node.c b/drivers/base/node.c
index 91636cd..43fa90b 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -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>
@@ -248,6 +249,105 @@
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;
+
+ /* discard ref obtained in find_memory_block() */
+ kobject_put(&mem_blk->sysdev.kobj);
+ }
+ 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;
@@ -267,6 +367,9 @@
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;
