mm, memory hotplug: small cleanup in online_pages()

We can reuse the nid we've determined instead of repeated pfn_to_nid()
usages.  Also zone_to_nid() should be a bit cheaper in general than
pfn_to_nid().

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d9bcb26..c832ef3 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1055,7 +1055,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
        arg.nr_pages = nr_pages;
        node_states_check_changes_online(nr_pages, zone, &arg);
 
-       nid = pfn_to_nid(pfn);
+       nid = zone_to_nid(zone);
 
        ret = memory_notify(MEM_GOING_ONLINE, &arg);
        ret = notifier_to_errno(ret);
@@ -1095,7 +1095,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
        pgdat_resize_unlock(zone->zone_pgdat, &flags);
 
        if (onlined_pages) {
-               node_states_set_node(zone_to_nid(zone), &arg);
+               node_states_set_node(nid, &arg);
                if (need_zonelists_rebuild)
                        build_all_zonelists(NULL, NULL);
                else
@@ -1107,7 +1107,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
        init_per_zone_wmark_min();
 
        if (onlined_pages) {
-               kswapd_run(zone_to_nid(zone));
+               kswapd_run(nid);
                kcompactd_run(nid);
        }