[PATCH v2 5/5] mm/memory_hotplug: online_pages cannot be 0 in online_pages()

From: David Hildenbrand
Date: Wed Aug 14 2019 - 11:41:28 EST


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 <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
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 f245fb50ba7f..01456fc66564 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;

--
2.21.0