Commit bf5b10b3 authored by Kefeng Wang's avatar Kefeng Wang Committed by Chen Jun
Browse files

mm, page_alloc: avoid page_to_pfn() in move_freepages() 



hulk inclusion
category: bugfix
bugzilla: 46856
CVE: NA

---------------------------

The start_pfn and end_pfn are already available in move_freepages_block(),
there is no need to go back and forth between page and pfn in move_freepages
and move_freepages_block, and pfn_valid_within() should validate pfn first
before touching the page.

Signed-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: default avatarChen Jun <chenjun102@huawei.com>
parent 3e93dbd2

mm/page_alloc.c

+13 −15
Original line number Diff line number Diff line
@@ -2361,19 +2361,21 @@ static inline struct page *__rmqueue_cma_fallback(struct zone *zone, 
 * boundary. If alignment is required, use move_freepages_block()

 */

static int move_freepages(struct zone *zone,

			  struct page *start_page, struct page *end_page,

			  unsigned long start_pfn, unsigned long end_pfn,

			  int migratetype, int *num_movable)

{

	struct page *page;

	unsigned long pfn;

	unsigned int order;

	int pages_moved = 0;



	for (page = start_page; page <= end_page;) {

		if (!pfn_valid_within(page_to_pfn(page))) {

			page++;

	for (pfn = start_pfn; pfn <= end_pfn;) {

		if (!pfn_valid_within(pfn)) {

			pfn++;

			continue;

		}



		page = pfn_to_page(pfn);

		if (!PageBuddy(page)) {

			/*

			 * We assume that pages that could be isolated for
@@ -2383,8 +2385,7 @@ static int move_freepages(struct zone *zone, 
			if (num_movable &&

					(PageLRU(page) || __PageMovable(page)))

				(*num_movable)++;



			page++;

			pfn++;

			continue;

		}
@@ -2394,7 +2395,7 @@ static int move_freepages(struct zone *zone, 


		order = buddy_order(page);

		move_to_free_list(page, zone, order, migratetype);

		page += 1 << order;

		pfn += 1 << order;

		pages_moved += 1 << order;

	}
@@ -2404,25 +2405,22 @@ static int move_freepages(struct zone *zone, 
int move_freepages_block(struct zone *zone, struct page *page,

				int migratetype, int *num_movable)

{

	unsigned long start_pfn, end_pfn;

	struct page *start_page, *end_page;

	unsigned long start_pfn, end_pfn, pfn;



	if (num_movable)

		*num_movable = 0;



	start_pfn = page_to_pfn(page);

	start_pfn = start_pfn & ~(pageblock_nr_pages-1);

	start_page = pfn_to_page(start_pfn);

	end_page = start_page + pageblock_nr_pages - 1;

	pfn = page_to_pfn(page);

	start_pfn = pfn & ~(pageblock_nr_pages - 1);

	end_pfn = start_pfn + pageblock_nr_pages - 1;



	/* Do not cross zone boundaries */

	if (!zone_spans_pfn(zone, start_pfn))

		start_page = page;

		start_pfn = pfn;

	if (!zone_spans_pfn(zone, end_pfn))

		return 0;



	return move_freepages(zone, start_page, end_page, migratetype,

	return move_freepages(zone, start_pfn, end_pfn, migratetype,

								num_movable);

}