mm/memory_hotplug: online_pages cannot be 0 in online_pages()

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.

Link: http://lkml.kernel.org/r/20190814154109.3448-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 13 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index aa54e15ea830..49f7bf91c25a 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -853,6 +853,7 @@ 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;
@@ -866,27 +867,22 @@ 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;