Memoryless nodes: introduce mask of nodes with memory

It is necessary to know if nodes have memory since we have recently begun to
add support for memoryless nodes.  For that purpose we introduce a two new
node states: N_HIGH_MEMORY and N_NORMAL_MEMORY.

A node has its bit in N_HIGH_MEMORY set if it has any memory regardless of the
type of mmemory.  If a node has memory then it has at least one zone defined
in its pgdat structure that is located in the pgdat itself.

A node has its bit in N_NORMAL_MEMORY set if it has a lower zone than
ZONE_HIGHMEM.  This means it is possible to allocate memory that is not
subject to kmap.

N_HIGH_MEMORY and N_NORMAL_MEMORY can then be used in various places to insure
that we do the right thing when we encounter a memoryless node.

[akpm@linux-foundation.org: build fix]
[Lee.Schermerhorn@hp.com: update N_HIGH_MEMORY node state for memory hotadd]
[y-goto@jp.fujitsu.com: Fix memory hotplug + sparsemem build]
Signed-off-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Bob Picco <bob.picco@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@skynet.ie>
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index df9d554bea30..9c12ae5e3695 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -217,6 +217,10 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
         zone->zone_pgdat->node_present_pages += onlined_pages;
 
         setup_per_zone_pages_min();
+        if (onlined_pages) {
+                kswapd_run(zone_to_nid(zone));
+                node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
+        }
 
         if (need_zonelists_rebuild)
                 build_all_zonelists();
@@ -271,9 +275,6 @@ int add_memory(int nid, u64 start, u64 size)
                 if (!pgdat)
                         return -ENOMEM;
                 new_pgdat = 1;
-                ret = kswapd_run(nid);
-                if (ret)
-                        goto error;
         }
 
         /* call arch's memory hotadd */