[PATCH v2 2/2] mm/memory_hotplug: cleanup __add_pages()

[David Hildenbrand]

Let's drop the basically unused section stuff and simplify. The logic
now matches the logic in __remove_pages().

Cc: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 mm/memory_hotplug.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 8fe7e32dad48..1a00b5a37ef6 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -307,8 +307,9 @@ static int check_hotplug_memory_addressable(unsigned long pfn,
 int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
 		struct mhp_restrictions *restrictions)
 {
+	const unsigned long end_pfn = pfn + nr_pages;
+	unsigned long cur_nr_pages;
 	int err;
-	unsigned long nr, start_sec, end_sec;
 	struct vmem_altmap *altmap = restrictions->altmap;
 
 	err = check_hotplug_memory_addressable(pfn, nr_pages);
@@ -331,18 +332,13 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
 	if (err)
 		return err;
 
-	start_sec = pfn_to_section_nr(pfn);
-	end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
-	for (nr = start_sec; nr <= end_sec; nr++) {
-		unsigned long pfns;
-
-		pfns = min(nr_pages, PAGES_PER_SECTION
-				- (pfn & ~PAGE_SECTION_MASK));
-		err = sparse_add_section(nid, pfn, pfns, altmap);
+	for (; pfn < end_pfn; pfn += cur_nr_pages) {
+		/* Select all remaining pages up to the next section boundary */
+		cur_nr_pages = min(end_pfn - pfn,
+				   SECTION_ALIGN_UP(pfn + 1) - pfn);
+		err = sparse_add_section(nid, pfn, cur_nr_pages, altmap);
 		if (err)
 			break;
-		pfn += pfns;
-		nr_pages -= pfns;
 		cond_resched();
 	}
 	vmemmap_populate_print_last();
-- 
2.24.1