Commit bb0e28eb authored by Zi Yan's avatar Zi Yan Committed by Andrew Morton
Browse files

mm: page_alloc: simplify pageblock migratetype check in __free_one_page() 

Move pageblock migratetype check code in the while loop to simplify the
logic. It also saves redundant buddy page checking code.

Link: https://lkml.kernel.org/r/20220401230804.1658207-1-zi.yan@sent.com
Link: https://lore.kernel.org/linux-mm/27ff69f9-60c5-9e59-feb2-295250077551@suse.cz/


Signed-off-by: default avatarZi Yan <ziy@nvidia.com>
Suggested-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 37931324

mm/page_alloc.c

+17 −29
Original line number Diff line number Diff line
@@ -1053,7 +1053,6 @@ static inline void __free_one_page(struct page *page, 
		int migratetype, fpi_t fpi_flags)

{

	struct capture_control *capc = task_capc(zone);

	unsigned int max_order = pageblock_order;

	unsigned long buddy_pfn;

	unsigned long combined_pfn;

	struct page *buddy;
@@ -1069,8 +1068,7 @@ static inline void __free_one_page(struct page *page, 
	VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);

	VM_BUG_ON_PAGE(bad_range(zone, page), page);



continue_merging:

	while (order < max_order) {

	while (order < MAX_ORDER - 1) {

		if (compaction_capture(capc, page, order, migratetype)) {

			__mod_zone_freepage_state(zone, -(1 << order),

								migratetype);
@@ -1081,6 +1079,22 @@ static inline void __free_one_page(struct page *page, 


		if (!page_is_buddy(page, buddy, order))

			goto done_merging;



		if (unlikely(order >= pageblock_order)) {

			/*

			 * We want to prevent merge between freepages on pageblock

			 * without fallbacks and normal pageblock. Without this,

			 * pageblock isolation could cause incorrect freepage or CMA

			 * accounting or HIGHATOMIC accounting.

			 */

			int buddy_mt = get_pageblock_migratetype(buddy);



			if (migratetype != buddy_mt

					&& (!migratetype_is_mergeable(migratetype) ||

						!migratetype_is_mergeable(buddy_mt)))

				goto done_merging;

		}



		/*

		 * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,

		 * merge with it and move up one order.
@@ -1094,32 +1108,6 @@ static inline void __free_one_page(struct page *page, 
		pfn = combined_pfn;

		order++;

	}

	if (order < MAX_ORDER - 1) {

		/* If we are here, it means order is >= pageblock_order.

		 * We want to prevent merge between freepages on pageblock

		 * without fallbacks and normal pageblock. Without this,

		 * pageblock isolation could cause incorrect freepage or CMA

		 * accounting or HIGHATOMIC accounting.

		 *

		 * We don't want to hit this code for the more frequent

		 * low-order merging.

		 */

		int buddy_mt;



		buddy_pfn = __find_buddy_pfn(pfn, order);

		buddy = page + (buddy_pfn - pfn);



		if (!page_is_buddy(page, buddy, order))

			goto done_merging;

		buddy_mt = get_pageblock_migratetype(buddy);



		if (migratetype != buddy_mt

				&& (!migratetype_is_mergeable(migratetype) ||

					!migratetype_is_mergeable(buddy_mt)))

			goto done_merging;

		max_order = order + 1;

		goto continue_merging;

	}



done_merging:

	set_buddy_order(page, order);