[PATCH v1 4/4] mm/memory_hotplug: online_pages cannot be 0 in online_pages()

[David Hildenbrand]

walk_system_ram_range() will fail with -EINVAL in case
online_pages_range() was never called (== no resource applicable in the
range). Otherwise, we will always call online_pages_range() with
nr_pages > 0 and, therefore, have online_pages > 0.

Remove that special handling.

Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Oscar Salvador <osalva...@suse.de>
Cc: Michal Hocko <mho...@suse.com>
Cc: Pavel Tatashin <pasha.tatas...@soleen.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: David Hildenbrand <da...@redhat.com>
---
 mm/memory_hotplug.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 87f85597a19e..07e72fe17495 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -854,6 +854,7 @@ int __ref online_pages(unsigned long pfn, unsigned long 
nr_pages, int online_typ
        ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
                online_pages_range);
        if (ret) {
+               /* not a single memory resource was applicable */
                if (need_zonelists_rebuild)
                        zone_pcp_reset(zone);
                goto failed_addition;
@@ -867,27 +868,22 @@ int __ref online_pages(unsigned long pfn, unsigned long 
nr_pages, int online_typ
 
        shuffle_zone(zone);
 
-       if (onlined_pages) {
-               node_states_set_node(nid, &arg);
-               if (need_zonelists_rebuild)
-                       build_all_zonelists(NULL);
-               else
-                       zone_pcp_update(zone);
-       }
+       node_states_set_node(nid, &arg);
+       if (need_zonelists_rebuild)
+               build_all_zonelists(NULL);
+       else
+               zone_pcp_update(zone);
 
        init_per_zone_wmark_min();
 
-       if (onlined_pages) {
-               kswapd_run(nid);
-               kcompactd_run(nid);
-       }
+       kswapd_run(nid);
+       kcompactd_run(nid);
 
        vm_total_pages = nr_free_pagecache_pages();
 
        writeback_set_ratelimit();
 
-       if (onlined_pages)
-               memory_notify(MEM_ONLINE, &arg);
+       memory_notify(MEM_ONLINE, &arg);
        mem_hotplug_done();
        return 0;
 
-- 
2.21.0