[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 <qiuxi...@huawei.com>
---
 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