[PATCH] fold me "mm: consider zone which is not fully populated to have holes"

[Michal Hocko]

- check valid section number in pfn_to_online_page - Vlastimil
- mark sections online after all struct pages are initialized in
  online_pages_range - Vlastimil

Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
 include/linux/memory_hotplug.h | 3 ++-
 mm/memory_hotplug.c            | 5 +++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index aec88657ec49..9e0249d0f5e4 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -22,8 +22,9 @@ struct resource;
 #define pfn_to_online_page(pfn)				\
 ({							\
 	struct page *___page = NULL;			\
+	unsigned long ___nr = pfn_to_section_nr(pfn);	\
 							\
-	if (online_section_nr(pfn_to_section_nr(pfn)))	\
+	if (___nr < NR_MEM_SECTIONS && online_section_nr(___nr))\
 		___page = pfn_to_page(pfn);		\
 	___page;					\
 })
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index de30822642c6..a31b547c11f0 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -746,14 +746,15 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
 	unsigned long onlined_pages = *(unsigned long *)arg;
 	struct page *page;
 
-	online_mem_sections(start_pfn, start_pfn + nr_pages);
-
 	if (PageReserved(pfn_to_page(start_pfn)))
 		for (i = 0; i < nr_pages; i++) {
 			page = pfn_to_page(start_pfn + i);
 			(*online_page_callback)(page);
 			onlined_pages++;
 		}
+
+	online_mem_sections(start_pfn, start_pfn + nr_pages);
+
 	*(unsigned long *)arg = onlined_pages;
 	return 0;
 }
-- 
2.11.0


-- 
Michal Hocko
SUSE Labs