[PATCH v2] mm: fix set pageblock migratetype in deferred struct page init

[Xishi Qiu]

Fixes: ac5d2539b238 ("mm: meminit: reduce number of times pageblocks are set during struct page init")
and stable 4.2+

on x86_64 MAX_ORDER_NR_PAGES is usually 4M, and a pageblock is usually 2M,
so we only set one pageblock's migratetype in deferred_free_range() if pfn
is aligned to MAX_ORDER_NR_PAGES. That means it causes uninitialized migratetype
blocks, you can see from "cat /proc/pagetypeinfo", almost half blocks are
Unmovable.

Also we missed to free the last block in deferred_init_memmap(), it causes
memory leak.

Signed-off-by: Xishi Qiu <qiuxishi@xxxxxxxxxx>
---
 mm/page_alloc.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2b258ec..e0ec3b6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1399,15 +1399,18 @@ static void __init deferred_free_range(struct page *page,
 		return;
 
 	/* Free a large naturally-aligned chunk if possible */
-	if (nr_pages == MAX_ORDER_NR_PAGES &&
-	    (pfn & (MAX_ORDER_NR_PAGES-1)) == 0) {
+	if (nr_pages == pageblock_nr_pages &&
+	    (pfn & (pageblock_nr_pages - 1)) == 0) {
 		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
-		__free_pages_boot_core(page, MAX_ORDER-1);
+		__free_pages_boot_core(page, pageblock_order);
 		return;
 	}
 
-	for (i = 0; i < nr_pages; i++, page++)
+	for (i = 0; i < nr_pages; i++, page++, pfn++) {
+		if ((pfn & (pageblock_nr_pages - 1)) == 0)
+			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
 		__free_pages_boot_core(page, 0);
+	}
 }
 
 /* Completion tracking for deferred_init_memmap() threads */
@@ -1475,9 +1478,9 @@ static int __init deferred_init_memmap(void *data)
 
 			/*
 			 * Ensure pfn_valid is checked every
-			 * MAX_ORDER_NR_PAGES for memory holes
+			 * pageblock_nr_pages for memory holes
 			 */
-			if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) {
+			if ((pfn & (pageblock_nr_pages - 1)) == 0) {
 				if (!pfn_valid(pfn)) {
 					page = NULL;
 					goto free_range;
@@ -1490,7 +1493,7 @@ static int __init deferred_init_memmap(void *data)
 			}
 
 			/* Minimise pfn page lookups and scheduler checks */
-			if (page && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) {
+			if (page && (pfn & (pageblock_nr_pages - 1)) != 0) {
 				page++;
 			} else {
 				nr_pages += nr_to_free;
@@ -1526,6 +1529,9 @@ free_range:
 			free_base_page = NULL;
 			free_base_pfn = nr_to_free = 0;
 		}
+		/* Free the last block of pages to allocator */
+		nr_pages += nr_to_free;
+		deferred_free_range(free_base_page, free_base_pfn, nr_to_free);
 
 		first_init_pfn = max(end_pfn, first_init_pfn);
 	}
-- 
1.8.3.1