In the near future, we want to have a single way to handover PageOffline
pages to the buddy, whereby they could have:
(a) Never been exposed to the buddy before: kept PageOffline when onlining
the memory block.
(b) Been allocated from the buddy, for example using
alloc_contig_range() to then be set PageOffline,
Let's start by making generic_online_page() less special compared to
ordinary page freeing (e.g., free_contig_range()), and perform the
debug_pagealloc_map_pages() call unconditionally, even when the online
callback might decide to keep the pages offline.
All pages are already initialized with PageOffline, so nobody touches
them either way.
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
mm/memory_hotplug.c | 10 +++++++++-
mm/page_alloc.c | 6 ------
2 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c43b4e7fb298..20af14e695c7 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -650,6 +650,7 @@ static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages)
* this and the first chunk to online will be pageblock_nr_pages.
*/
for (pfn = start_pfn; pfn < end_pfn;) {
+ struct page *page = pfn_to_page(pfn);
int order;
/*
@@ -664,7 +665,14 @@ static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages)
else
order = MAX_PAGE_ORDER;
- (*online_page_callback)(pfn_to_page(pfn), order);
+ /*
+ * Exposing the page to the buddy by freeing can cause
+ * issues with debug_pagealloc enabled: some archs don't
+ * like double-unmappings. So treat them like any pages that
+ * were allocated from the buddy.
+ */
+ debug_pagealloc_map_pages(page, 1 << order);
+ (*online_page_callback)(page, order);
pfn += (1UL << order);
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cc3296cf8c95..01927f03af0b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1293,12 +1293,6 @@ void __meminit __free_pages_core(struct page *page, unsigned int order,
set_page_count(p, 0);
}
- /*
- * Freeing the page with debug_pagealloc enabled will try to
- * unmap it; some archs don't like double-unmappings, so
- * map it first.
- */
- debug_pagealloc_map_pages(page, nr_pages);
adjust_managed_page_count(page, nr_pages);
} else {
for (loop = 0; loop < nr_pages; loop++, p++) {
--
2.47.1
