On Mon, Jan 24, 2022 at 12:59:57PM -0500, Zi Yan wrote: > 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. > > Remove MIGRARTE_CMA and MIGRATE_ISOLATE from fallbacks list, since they > are never used. > > [1] https://lore.kernel.org/linux-mm/20211130100853.GP3366@xxxxxxxxxxxxxxxxxxx/ > > Signed-off-by: Zi Yan <ziy@xxxxxxxxxx> > Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> > --- > include/linux/mmzone.h | 11 +++++++++++ > mm/page_alloc.c | 44 ++++++++++++++++++++---------------------- > 2 files changed, 32 insertions(+), 23 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index aed44e9b5d89..71b77aab748d 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -83,6 +83,17 @@ static inline bool is_migrate_movable(int mt) > return is_migrate_cma(mt) || mt == MIGRATE_MOVABLE; > } > > +/* > + * Check whether a migratetype can be merged with another migratetype. > + * > + * It is only mergeable when it can fall back to other migratetypes for > + * allocation. See fallbacks[MIGRATE_TYPES][3] in page_alloc.c. > + */ > +static inline bool migratetype_is_mergeable(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..5a91d4d9279a 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1117,25 +1117,24 @@ 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))) { > - int buddy_mt; > + int buddy_mt; > > - buddy_pfn = __find_buddy_pfn(pfn, order); > - buddy = page + (buddy_pfn - pfn); > - buddy_mt = get_pageblock_migratetype(buddy); > + buddy_pfn = __find_buddy_pfn(pfn, order); > + buddy = page + (buddy_pfn - pfn); > + buddy_mt = get_pageblock_migratetype(buddy); > > - if (migratetype != buddy_mt > - && (is_migrate_isolate(migratetype) || > - is_migrate_isolate(buddy_mt))) > - goto done_merging; > - } > + if (migratetype != buddy_mt > + && (!migratetype_is_mergeable(migratetype) || > + !migratetype_is_mergeable(buddy_mt))) > + goto done_merging; > max_order = order + 1; > goto continue_merging; > } > @@ -2479,17 +2478,13 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order, > /* > * This array describes the order lists are fallen back to when > * the free lists for the desirable migrate type are depleted > + * > + * The other migratetypes do not have fallbacks. > */ > 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 }, > -#ifdef CONFIG_CMA > - [MIGRATE_CMA] = { MIGRATE_TYPES }, /* Never used */ > -#endif > -#ifdef CONFIG_MEMORY_ISOLATION > - [MIGRATE_ISOLATE] = { MIGRATE_TYPES }, /* Never used */ > -#endif > }; > > #ifdef CONFIG_CMA > @@ -2795,8 +2790,8 @@ 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 pageblocks (i.e., they can merge with others) */ > + if (migratetype_is_mergeable(mt)) { > zone->nr_reserved_highatomic += pageblock_nr_pages; > set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC); > move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL); > @@ -3545,8 +3540,11 @@ 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 pageblocks (i.e., they can merge > + * with others) > + */ > + if (migratetype_is_mergeable(mt)) > set_pageblock_migratetype(page, > MIGRATE_MOVABLE); > } > -- > 2.34.1 > -- Sincerely yours, Mike.
