From: Zi Yan <ziy@xxxxxxxxxx> This is done in addition to MIGRATE_ISOLATE pageblock merge avoidance. It prepares for the upcoming removal of the MAX_ORDER-1 alignment requirement for CMA and alloc_contig_range(). MIGRARTE_HIGHATOMIC should not merge with other migratetypes like MIGRATE_ISOLATE and MIGRARTE_CMA[1], so this commit prevents that too. Also add MIGRARTE_HIGHATOMIC to fallbacks array for completeness. [1] https://lore.kernel.org/linux-mm/20211130100853.GP3366@xxxxxxxxxxxxxxxxxxx/ Signed-off-by: Zi Yan <ziy@xxxxxxxxxx> --- include/linux/mmzone.h | 6 ++++++ mm/page_alloc.c | 28 ++++++++++++++++++---------- 2 files changed, 24 insertions(+), 10 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index aed44e9b5d89..0aa549653e4e 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -83,6 +83,12 @@ static inline bool is_migrate_movable(int mt) return is_migrate_cma(mt) || mt == MIGRATE_MOVABLE; } +/* See fallbacks[MIGRATE_TYPES][3] in page_alloc.c */ +static inline bool migratetype_has_fallback(int mt) +{ + return mt < MIGRATE_PCPTYPES; +} + #define for_each_migratetype_order(order, type) \ for (order = 0; order < MAX_ORDER; order++) \ for (type = 0; type < MIGRATE_TYPES; type++) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8dd6399bafb5..5193c953dbf8 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1042,6 +1042,12 @@ buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn, return page_is_buddy(higher_page, higher_buddy, order + 1); } +static inline bool has_non_fallback_pageblock(struct zone *zone) +{ + return has_isolate_pageblock(zone) || zone_cma_pages(zone) != 0 || + zone->nr_reserved_highatomic != 0; +} + /* * Freeing function for a buddy system allocator. * @@ -1117,14 +1123,15 @@ static inline void __free_one_page(struct page *page, } if (order < MAX_ORDER - 1) { /* If we are here, it means order is >= pageblock_order. - * We want to prevent merge between freepages on isolate - * pageblock and normal pageblock. Without this, pageblock - * isolation could cause incorrect freepage or CMA accounting. + * 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. */ - if (unlikely(has_isolate_pageblock(zone))) { + if (unlikely(has_non_fallback_pageblock(zone))) { int buddy_mt; buddy_pfn = __find_buddy_pfn(pfn, order); @@ -1132,8 +1139,8 @@ static inline void __free_one_page(struct page *page, buddy_mt = get_pageblock_migratetype(buddy); if (migratetype != buddy_mt - && (is_migrate_isolate(migratetype) || - is_migrate_isolate(buddy_mt))) + && (!migratetype_has_fallback(migratetype) || + !migratetype_has_fallback(buddy_mt))) goto done_merging; } max_order = order + 1; @@ -2484,6 +2491,7 @@ static int fallbacks[MIGRATE_TYPES][3] = { [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_TYPES }, [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES }, [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_TYPES }, + [MIGRATE_HIGHATOMIC] = { MIGRATE_TYPES }, /* Never used */ #ifdef CONFIG_CMA [MIGRATE_CMA] = { MIGRATE_TYPES }, /* Never used */ #endif @@ -2795,8 +2803,8 @@ static void reserve_highatomic_pageblock(struct page *page, struct zone *zone, /* Yoink! */ mt = get_pageblock_migratetype(page); - if (!is_migrate_highatomic(mt) && !is_migrate_isolate(mt) - && !is_migrate_cma(mt)) { + /* Only reserve normal pageblock */ + if (migratetype_has_fallback(mt)) { zone->nr_reserved_highatomic += pageblock_nr_pages; set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC); move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL); @@ -3545,8 +3553,8 @@ int __isolate_free_page(struct page *page, unsigned int order) struct page *endpage = page + (1 << order) - 1; for (; page < endpage; page += pageblock_nr_pages) { int mt = get_pageblock_migratetype(page); - if (!is_migrate_isolate(mt) && !is_migrate_cma(mt) - && !is_migrate_highatomic(mt)) + /* Only change normal pageblock */ + if (migratetype_has_fallback(mt)) set_pageblock_migratetype(page, MIGRATE_MOVABLE); } -- 2.34.1
