[PATCH] mm/page_alloc: Make deferred page init free pages in MAX_ORDER blocks

[Kirill A. Shutemov]

Normal page init path frees pages during the boot in MAX_ORDER chunks,
but deferred page init path does it in pageblock blocks.

Change deferred page init path to work in MAX_ORDER blocks.

For cases when pageblock is larger than MAX_ORDER, set migrate type to
MIGRATE_MOVABLE for all pageblocks covered by the page.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---

Note: the patch depends on the new definiton of MAX_ORDER.

---
 include/linux/mmzone.h |  2 ++
 mm/page_alloc.c        | 19 ++++++++++---------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 96599cb9eb62..f53fe3a7ca45 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -32,6 +32,8 @@
 #endif
 #define MAX_ORDER_NR_PAGES (1 << MAX_ORDER)
 
+#define IS_MAX_ORDER_ALIGNED(pfn) IS_ALIGNED(pfn, MAX_ORDER_NR_PAGES)
+
 /*
  * PAGE_ALLOC_COSTLY_ORDER is the order at which allocations are deemed
  * costly to service.  That is between allocation orders which should
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 87d760236dba..fc02a243425d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1875,9 +1875,10 @@ static void __init deferred_free_range(unsigned long pfn,
 	page = pfn_to_page(pfn);
 
 	/* Free a large naturally-aligned chunk if possible */
-	if (nr_pages == pageblock_nr_pages && pageblock_aligned(pfn)) {
-		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
-		__free_pages_core(page, pageblock_order);
+	if (nr_pages == MAX_ORDER_NR_PAGES && IS_MAX_ORDER_ALIGNED(pfn)) {
+		for (i = 0; i < nr_pages; i += pageblock_nr_pages)
+			set_pageblock_migratetype(page + i, MIGRATE_MOVABLE);
+		__free_pages_core(page, MAX_ORDER);
 		return;
 	}
 
@@ -1901,19 +1902,19 @@ static inline void __init pgdat_init_report_one_done(void)
 /*
  * Returns true if page needs to be initialized or freed to buddy allocator.
  *
- * We check if a current large page is valid by only checking the validity
+ * We check if a current MAX_ORDER block is valid by only checking the validity
  * of the head pfn.
  */
 static inline bool __init deferred_pfn_valid(unsigned long pfn)
 {
-	if (pageblock_aligned(pfn) && !pfn_valid(pfn))
+	if (IS_MAX_ORDER_ALIGNED(pfn) && !pfn_valid(pfn))
 		return false;
 	return true;
 }
 
 /*
  * Free pages to buddy allocator. Try to free aligned pages in
- * pageblock_nr_pages sizes.
+ * MAX_ORDER_NR_PAGES sizes.
  */
 static void __init deferred_free_pages(unsigned long pfn,
 				       unsigned long end_pfn)
@@ -1924,7 +1925,7 @@ static void __init deferred_free_pages(unsigned long pfn,
 		if (!deferred_pfn_valid(pfn)) {
 			deferred_free_range(pfn - nr_free, nr_free);
 			nr_free = 0;
-		} else if (pageblock_aligned(pfn)) {
+		} else if (IS_MAX_ORDER_ALIGNED(pfn)) {
 			deferred_free_range(pfn - nr_free, nr_free);
 			nr_free = 1;
 		} else {
@@ -1937,7 +1938,7 @@ static void __init deferred_free_pages(unsigned long pfn,
 
 /*
  * Initialize struct pages.  We minimize pfn page lookups and scheduler checks
- * by performing it only once every pageblock_nr_pages.
+ * by performing it only once every MAX_ORDER_NR_PAGES.
  * Return number of pages initialized.
  */
 static unsigned long  __init deferred_init_pages(struct zone *zone,
@@ -1953,7 +1954,7 @@ static unsigned long  __init deferred_init_pages(struct zone *zone,
 		if (!deferred_pfn_valid(pfn)) {
 			page = NULL;
 			continue;
-		} else if (!page || pageblock_aligned(pfn)) {
+		} else if (!page || IS_MAX_ORDER_ALIGNED(pfn)) {
 			page = pfn_to_page(pfn);
 		} else {
 			page++;
-- 
2.39.2