Subject: [PATCH v1 2/2] mm/memory_hotplug: remove is_mem_section_removable()

From: David Hildenbrand <[email-masked]>
Date: Tue, 7 Apr 2020 15:54:16 +0200

Fortunately, all users of is_mem_section_removable() are gone. Get rid of
it, including some now unnecessary functions.

Cc: Michael Ellerman <[email-masked]>
Cc: Benjamin Herrenschmidt <[email-masked]>
Cc: Michal Hocko <[email-masked]>
Cc: Andrew Morton <[email-masked]>
Cc: Oscar Salvador <[email-masked]>
Cc: Baoquan He <[email-masked]>
Cc: Wei Yang <[email-masked]>
Signed-off-by: David Hildenbrand <[email-masked]>
---
 include/linux/memory_hotplug.h |  7 ----
 mm/memory_hotplug.c            | 75 ----------------------------------
 2 files changed, 82 deletions(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 93d9ada74ddd..7dca9cd6076b 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -314,19 +314,12 @@ static inline void pgdat_resize_init(struct pglist_data *pgdat) {}
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 
-extern bool is_mem_section_removable(unsigned long pfn, unsigned long nr_pages);
 extern void try_offline_node(int nid);
 extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
 extern int remove_memory(int nid, u64 start, u64 size);
 extern void __remove_memory(int nid, u64 start, u64 size);
 
 #else
-static inline bool is_mem_section_removable(unsigned long pfn,
-					unsigned long nr_pages)
-{
-	return false;
-}
-
 static inline void try_offline_node(int nid) {}
 
 static inline int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 47cf6036eb31..4d338d546d52 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1112,81 +1112,6 @@ int add_memory(int nid, u64 start, u64 size)
 EXPORT_SYMBOL_GPL(add_memory);
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-/*
- * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
- * set and the size of the free page is given by page_order(). Using this,
- * the function determines if the pageblock contains only free pages.
- * Due to buddy contraints, a free page at least the size of a pageblock will
- * be located at the start of the pageblock
- */
-static inline int pageblock_free(struct page *page)
-{
-	return PageBuddy(page) && page_order(page) >= pageblock_order;
-}
-
-/* Return the pfn of the start of the next active pageblock after a given pfn */
-static unsigned long next_active_pageblock(unsigned long pfn)
-{
-	struct page *page = pfn_to_page(pfn);
-
-	/* Ensure the starting page is pageblock-aligned */
-	BUG_ON(pfn & (pageblock_nr_pages - 1));
-
-	/* If the entire pageblock is free, move to the end of free page */
-	if (pageblock_free(page)) {
-		int order;
-		/* be careful. we don't have locks, page_order can be changed.*/
-		order = page_order(page);
-		if ((order < MAX_ORDER) && (order >= pageblock_order))
-			return pfn + (1 << order);
-	}
-
-	return pfn + pageblock_nr_pages;
-}
-
-static bool is_pageblock_removable_nolock(unsigned long pfn)
-{
-	struct page *page = pfn_to_page(pfn);
-	struct zone *zone;
-
-	/*
-	 * We have to be careful here because we are iterating over memory
-	 * sections which are not zone aware so we might end up outside of
-	 * the zone but still within the section.
-	 * We have to take care about the node as well. If the node is offline
-	 * its NODE_DATA will be NULL - see page_zone.
-	 */
-	if (!node_online(page_to_nid(page)))
-		return false;
-
-	zone = page_zone(page);
-	pfn = page_to_pfn(page);
-	if (!zone_spans_pfn(zone, pfn))
-		return false;
-
-	return !has_unmovable_pages(zone, page, MIGRATE_MOVABLE,
-				    MEMORY_OFFLINE);
-}
-
-/* Checks if this range of memory is likely to be hot-removable. */
-bool is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
-{
-	unsigned long end_pfn, pfn;
-
-	end_pfn = min(start_pfn + nr_pages,
-			zone_end_pfn(page_zone(pfn_to_page(start_pfn))));
-
-	/* Check the starting page of each pageblock within the range */
-	for (pfn = start_pfn; pfn < end_pfn; pfn = next_active_pageblock(pfn)) {
-		if (!is_pageblock_removable_nolock(pfn))
-			return false;
-		cond_resched();
-	}
-
-	/* All pageblocks in the memory block are likely to be hot-removable */
-	return true;
-}
-
 /*
  * Confirm all pages in a range [start, end) belong to the same zone (skipping
  * memory holes). When true, return the zone.
-- 
2.25.1