[PATCH 3/3] mm/memory_hotplug: Cleanup unregister_mem_sect_under_nodes

[osalvador]

From: Oscar Salvador <osalva...@suse.de>

With the assumption that the relationship between
memory_block <-> node is 1:1, we can refactor this function a bit.

This assumption is being taken from register_mem_sect_under_node()
code.

register_mem_sect_under_node() takes the mem_blk's nid, and compares it
to the pfn's nid we are checking.
If they match, we go ahead and link both objects.
Once done, we just return.

So, the relationship between memory_block <-> node seems to stand.

Currently, unregister_mem_sect_under_nodes() defines a nodemask_t
which is being checked in the loop to see if we have already unliked certain 
node.
But since a memory_block can only belong to a node, we can drop the nodemask
and the check within the loop.

If we find a match between the mem_block->nid and the nid of the
pfn we are checking, we unlink the objects and return, as unlink the objects
once is enough.

Signed-off-by: Oscar Salvador <osalva...@suse.de>
---
 drivers/base/node.c | 30 +++++++++++-------------------
 1 file changed, 11 insertions(+), 19 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index dd3bdab230b2..0657ed70bddd 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -448,35 +448,27 @@ int register_mem_sect_under_node(struct memory_block 
*mem_blk, void *arg)
        return 0;
 }
 
-/* unregister memory section under all nodes that it spans */
+/* unregister memory section from the node it belongs to */
 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
                                    unsigned long phys_index)
 {
-       NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
        unsigned long pfn, sect_start_pfn, sect_end_pfn;
-
-       if (!unlinked_nodes)
-               return -ENOMEM;
-       nodes_clear(*unlinked_nodes);
+       int nid = mem_blk->nid;
 
        sect_start_pfn = section_nr_to_pfn(phys_index);
        sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
        for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
-               int nid;
+               int page_nid = get_nid_for_pfn(pfn);
 
-               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]->dev.kobj,
-                        kobject_name(&mem_blk->dev.kobj));
-               sysfs_remove_link(&mem_blk->dev.kobj,
-                        kobject_name(&node_devices[nid]->dev.kobj));
+               if (page_nid >= 0 && page_nid == nid) {
+                       sysfs_remove_link(&node_devices[nid]->dev.kobj,
+                                kobject_name(&mem_blk->dev.kobj));
+                       sysfs_remove_link(&mem_blk->dev.kobj,
+                                kobject_name(&node_devices[nid]->dev.kobj));
+                       break;
+               }
        }
-       NODEMASK_FREE(unlinked_nodes);
+
        return 0;
 }
 
-- 
2.13.6