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Shutemov" , Johannes Weiner , Baolin Wang , Kemeng Shi , Mel Gorman , Rohan Puri , Mcgrof Chamberlain , Adam Manzanares , "Vishal Moola (Oracle)" Subject: [PATCH v1 2/4] mm/compaction: add support for >0 order folio memory compaction. Date: Mon, 13 Nov 2023 12:01:55 -0500 Message-ID: <20231113170157.280181-3-zi.yan@sent.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231113170157.280181-1-zi.yan@sent.com> References: <20231113170157.280181-1-zi.yan@sent.com> Reply-To: Zi Yan MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zi Yan Before, memory compaction only migrates order-0 folios and skips >0 order folios. This commit adds support for >0 order folio compaction by keeping isolated free pages at their original size without splitting them into order-0 pages and using them directly during migration process. What is different from the prior implementation: 1. All isolated free pages are kept in a MAX_ORDER+1 array of page lists, where each page list stores free pages in the same order. 2. All free pages are not post_alloc_hook() processed nor buddy pages, although their orders are stored in first page's private like buddy pages. 3. During migration, in new page allocation time (i.e., in compaction_alloc()), free pages are then processed by post_alloc_hook(). When migration fails and a new page is returned (i.e., in compaction_free()), free pages are restored by reversing the post_alloc_hook() operations. Step 3 is done for a latter optimization that splitting and/or merging free pages during compaction becomes easier. Signed-off-by: Zi Yan --- mm/compaction.c | 160 ++++++++++++++++++++++++++++++------------------ mm/internal.h | 7 ++- 2 files changed, 108 insertions(+), 59 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 5217dd35b493..ec6b5cc7e907 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -66,45 +66,64 @@ static inline void count_compact_events(enum vm_event_i= tem item, long delta) #define COMPACTION_HPAGE_ORDER (PMD_SHIFT - PAGE_SHIFT) #endif =20 -static unsigned long release_freepages(struct list_head *freelist) +static void init_page_list(struct page_list *p) { - struct page *page, *next; - unsigned long high_pfn =3D 0; - - list_for_each_entry_safe(page, next, freelist, lru) { - unsigned long pfn =3D page_to_pfn(page); - list_del(&page->lru); - __free_page(page); - if (pfn > high_pfn) - high_pfn =3D pfn; - } - - return high_pfn; + INIT_LIST_HEAD(&p->pages); + p->nr_pages =3D 0; } =20 -static void split_map_pages(struct list_head *list) +static void split_map_pages(struct page_list *freepages) { unsigned int i, order, nr_pages; struct page *page, *next; LIST_HEAD(tmp_list); =20 - list_for_each_entry_safe(page, next, list, lru) { - list_del(&page->lru); + for (order =3D 0; order <=3D MAX_ORDER; order++) { + freepages[order].nr_pages =3D 0; + + list_for_each_entry_safe(page, next, &freepages[order].pages, lru) { + list_del(&page->lru); =20 - order =3D page_private(page); - nr_pages =3D 1 << order; + nr_pages =3D 1 << order; =20 - post_alloc_hook(page, order, __GFP_MOVABLE); - if (order) - split_page(page, order); + post_alloc_hook(page, order, __GFP_MOVABLE); + if (order) + split_page(page, order); =20 - for (i =3D 0; i < nr_pages; i++) { - list_add(&page->lru, &tmp_list); - page++; + for (i =3D 0; i < nr_pages; i++) { + list_add(&page->lru, &tmp_list); + page++; + } + freepages[order].nr_pages +=3D nr_pages; } + list_splice(&tmp_list, &freepages[order].pages); } +} =20 - list_splice(&tmp_list, list); +static unsigned long release_free_list(struct page_list *freepages) +{ + int order; + unsigned long high_pfn =3D 0; + + for (order =3D 0; order <=3D MAX_ORDER; order++) { + struct page *page, *next; + + list_for_each_entry_safe(page, next, &freepages[order].pages, lru) { + unsigned long pfn =3D page_to_pfn(page); + + list_del(&page->lru); + /* + * Convert free pages into post allocation pages, so + * that we can free them via __free_page. + */ + post_alloc_hook(page, order, __GFP_MOVABLE); + __free_pages(page, order); + if (pfn > high_pfn) + high_pfn =3D pfn; + } + freepages[order].nr_pages =3D 0; + } + return high_pfn; } =20 #ifdef CONFIG_COMPACTION @@ -583,7 +602,7 @@ static bool compact_unlock_should_abort(spinlock_t *loc= k, static unsigned long isolate_freepages_block(struct compact_control *cc, unsigned long *start_pfn, unsigned long end_pfn, - struct list_head *freelist, + struct page_list *freelist, unsigned int stride, bool strict) { @@ -657,7 +676,8 @@ static unsigned long isolate_freepages_block(struct com= pact_control *cc, nr_scanned +=3D isolated - 1; total_isolated +=3D isolated; cc->nr_freepages +=3D isolated; - list_add_tail(&page->lru, freelist); + list_add_tail(&page->lru, &freelist[order].pages); + freelist[order].nr_pages++; =20 if (!strict && cc->nr_migratepages <=3D cc->nr_freepages) { blockpfn +=3D isolated; @@ -722,7 +742,11 @@ isolate_freepages_range(struct compact_control *cc, unsigned long start_pfn, unsigned long end_pfn) { unsigned long isolated, pfn, block_start_pfn, block_end_pfn; - LIST_HEAD(freelist); + int order; + struct page_list tmp_freepages[MAX_ORDER + 1]; + + for (order =3D 0; order <=3D MAX_ORDER; order++) + init_page_list(&tmp_freepages[order]); =20 pfn =3D start_pfn; block_start_pfn =3D pageblock_start_pfn(pfn); @@ -753,7 +777,7 @@ isolate_freepages_range(struct compact_control *cc, break; =20 isolated =3D isolate_freepages_block(cc, &isolate_start_pfn, - block_end_pfn, &freelist, 0, true); + block_end_pfn, tmp_freepages, 0, true); =20 /* * In strict mode, isolate_freepages_block() returns 0 if @@ -770,15 +794,15 @@ isolate_freepages_range(struct compact_control *cc, */ } =20 - /* __isolate_free_page() does not map the pages */ - split_map_pages(&freelist); - if (pfn < end_pfn) { /* Loop terminated early, cleanup. */ - release_freepages(&freelist); + release_free_list(tmp_freepages); return 0; } =20 + /* __isolate_free_page() does not map the pages */ + split_map_pages(tmp_freepages); + /* We don't use freelists for anything. */ return pfn; } @@ -1462,7 +1486,7 @@ fast_isolate_around(struct compact_control *cc, unsig= ned long pfn) if (!page) return; =20 - isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false= ); + isolate_freepages_block(cc, &start_pfn, end_pfn, cc->freepages, 1, false); =20 /* Skip this pageblock in the future as it's full or nearly full */ if (start_pfn =3D=3D end_pfn && !cc->no_set_skip_hint) @@ -1591,7 +1615,7 @@ static void fast_isolate_freepages(struct compact_con= trol *cc) nr_scanned +=3D nr_isolated - 1; total_isolated +=3D nr_isolated; cc->nr_freepages +=3D nr_isolated; - list_add_tail(&page->lru, &cc->freepages); + list_add_tail(&page->lru, &cc->freepages[order].pages); count_compact_events(COMPACTISOLATED, nr_isolated); } else { /* If isolation fails, abort the search */ @@ -1665,13 +1689,12 @@ static void isolate_freepages(struct compact_contro= l *cc) unsigned long isolate_start_pfn; /* exact pfn we start at */ unsigned long block_end_pfn; /* end of current pageblock */ unsigned long low_pfn; /* lowest pfn scanner is able to scan */ - struct list_head *freelist =3D &cc->freepages; unsigned int stride; =20 /* Try a small search of the free lists for a candidate */ fast_isolate_freepages(cc); if (cc->nr_freepages) - goto splitmap; + return; =20 /* * Initialise the free scanner. The starting point is where we last @@ -1731,7 +1754,7 @@ static void isolate_freepages(struct compact_control = *cc) =20 /* Found a block suitable for isolating free pages from. */ nr_isolated =3D isolate_freepages_block(cc, &isolate_start_pfn, - block_end_pfn, freelist, stride, false); + block_end_pfn, cc->freepages, stride, false); =20 /* Update the skip hint if the full pageblock was scanned */ if (isolate_start_pfn =3D=3D block_end_pfn) @@ -1772,10 +1795,6 @@ static void isolate_freepages(struct compact_control= *cc) * and the loop terminated due to isolate_start_pfn < low_pfn */ cc->free_pfn =3D isolate_start_pfn; - -splitmap: - /* __isolate_free_page() does not map the pages */ - split_map_pages(freelist); } =20 /* @@ -1786,23 +1805,22 @@ static struct folio *compaction_alloc(struct folio = *src, unsigned long data) { struct compact_control *cc =3D (struct compact_control *)data; struct folio *dst; + int order =3D folio_order(src); =20 - /* this makes migrate_pages() split the source page and retry */ - if (folio_order(src) > 0) - return NULL; - - if (list_empty(&cc->freepages)) { + if (!cc->freepages[order].nr_pages) { isolate_freepages(cc); - - if (list_empty(&cc->freepages)) + if (!cc->freepages[order].nr_pages) return NULL; } =20 - dst =3D list_entry(cc->freepages.next, struct folio, lru); + dst =3D list_first_entry(&cc->freepages[order].pages, struct folio, lru); + cc->freepages[order].nr_pages--; list_del(&dst->lru); - cc->nr_freepages--; - - return dst; + post_alloc_hook(&dst->page, order, __GFP_MOVABLE); + if (order) + prep_compound_page(&dst->page, order); + cc->nr_freepages -=3D 1 << order; + return page_rmappable_folio(&dst->page); } =20 /* @@ -1813,9 +1831,34 @@ static struct folio *compaction_alloc(struct folio *= src, unsigned long data) static void compaction_free(struct folio *dst, unsigned long data) { struct compact_control *cc =3D (struct compact_control *)data; + int order =3D folio_order(dst); + struct page *page =3D &dst->page; + + if (order) { + int i; =20 - list_add(&dst->lru, &cc->freepages); - cc->nr_freepages++; + page[1].flags &=3D ~PAGE_FLAGS_SECOND; + for (i =3D 1; i < (1 << order); i++) { + page[i].mapping =3D NULL; + clear_compound_head(&page[i]); + page[i].flags &=3D ~PAGE_FLAGS_CHECK_AT_PREP; + } + + } + /* revert post_alloc_hook() operations */ + page->mapping =3D NULL; + page->flags &=3D ~PAGE_FLAGS_CHECK_AT_PREP; + set_page_count(page, 0); + page_mapcount_reset(page); + reset_page_owner(page, order); + page_table_check_free(page, order); + arch_free_page(page, order); + set_page_private(page, order); + INIT_LIST_HEAD(&dst->lru); + + list_add(&dst->lru, &cc->freepages[order].pages); + cc->freepages[order].nr_pages++; + cc->nr_freepages +=3D 1 << order; } =20 /* possible outcome of isolate_migratepages */ @@ -2439,6 +2482,7 @@ compact_zone(struct compact_control *cc, struct captu= re_control *capc) const bool sync =3D cc->mode !=3D MIGRATE_ASYNC; bool update_cached; unsigned int nr_succeeded =3D 0; + int order; =20 /* * These counters track activities during zone compaction. Initialize @@ -2448,7 +2492,8 @@ compact_zone(struct compact_control *cc, struct captu= re_control *capc) cc->total_free_scanned =3D 0; cc->nr_migratepages =3D 0; cc->nr_freepages =3D 0; - INIT_LIST_HEAD(&cc->freepages); + for (order =3D 0; order <=3D MAX_ORDER; order++) + init_page_list(&cc->freepages[order]); INIT_LIST_HEAD(&cc->migratepages); =20 cc->migratetype =3D gfp_migratetype(cc->gfp_mask); @@ -2634,7 +2679,7 @@ compact_zone(struct compact_control *cc, struct captu= re_control *capc) * so we don't leave any returned pages behind in the next attempt. */ if (cc->nr_freepages > 0) { - unsigned long free_pfn =3D release_freepages(&cc->freepages); + unsigned long free_pfn =3D release_free_list(cc->freepages); =20 cc->nr_freepages =3D 0; VM_BUG_ON(free_pfn =3D=3D 0); @@ -2653,7 +2698,6 @@ compact_zone(struct compact_control *cc, struct captu= re_control *capc) =20 trace_mm_compaction_end(cc, start_pfn, end_pfn, sync, ret); =20 - VM_BUG_ON(!list_empty(&cc->freepages)); VM_BUG_ON(!list_empty(&cc->migratepages)); =20 return ret; diff --git a/mm/internal.h b/mm/internal.h index 8450562744cf..46c8bb94ecbb 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -473,6 +473,11 @@ int split_free_page(struct page *free_page, /* * in mm/compaction.c */ + +struct page_list { + struct list_head pages; + unsigned long nr_pages; +}; /* * compact_control is used to track pages being migrated and the free pages * they are being migrated to during memory compaction. The free_pfn starts @@ -481,7 +486,7 @@ int split_free_page(struct page *free_page, * completes when free_pfn <=3D migrate_pfn */ struct compact_control { - struct list_head freepages; /* List of free pages to migrate to */ + struct page_list freepages[MAX_ORDER + 1]; /* List of free pages to migra= te to */ struct list_head migratepages; /* List of pages being migrated */ unsigned int nr_freepages; /* Number of isolated free pages */ unsigned int nr_migratepages; /* Number of pages to migrate */ --=20 2.42.0