[PATCH v9 2/8] mm,memory_hotplug: Relax fully spanned sections check

Oscar Salvador
2021-04-16T11:24:32Z

When using self-hosted vmemmap pages, the number of pages passed to
{online,offline}_pages might not fully span sections, but they always
fully span pageblocks.
Relax the check account for that case.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
mm/memory_hotplug.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 0cdbbfbc5757..25e59d5dc13c 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -838,9 +838,14 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
int ret;
struct memory_notify arg;

- /* We can only online full sections (e.g., SECTION_IS_ONLINE) */
+ /* We can only offline full sections (e.g., SECTION_IS_ONLINE).
+ * However, when using e.g: memmap_on_memory, some pages are initialized
+ * prior to calling in here. The remaining amount of pages must be
+ * pageblock aligned.
+ */
if (WARN_ON_ONCE(!nr_pages ||
- !IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION)))
+ !IS_ALIGNED(pfn, pageblock_nr_pages) ||
+ !IS_ALIGNED(pfn + nr_pages, PAGES_PER_SECTION)))
return -EINVAL;

mem_hotplug_begin();
@@ -1573,9 +1578,14 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
int ret, node;
char *reason;

- /* We can only offline full sections (e.g., SECTION_IS_ONLINE) */
+ /* We can only offline full sections (e.g., SECTION_IS_ONLINE).
+ * However, when using e.g: memmap_on_memory, some pages are initialized
+ * prior to calling in here. The remaining amount of pages must be
+ * pageblock aligned.
+ */
if (WARN_ON_ONCE(!nr_pages ||
- !IS_ALIGNED(start_pfn | nr_pages, PAGES_PER_SECTION)))
+ !IS_ALIGNED(start_pfn, pageblock_nr_pages) ||
+ !IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION)))
return -EINVAL;

mem_hotplug_begin();
--
2.16.3