6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Huang Ying <ying.huang@xxxxxxxxx> [ Upstream commit 64c8902ed4418317cd416c566f896bd4a92b2efc ] This is a preparation patch to batch the folio unmapping and moving. In this patch, unmap_and_move() is split to migrate_folio_unmap() and migrate_folio_move(). So, we can batch _unmap() and _move() in different loops later. To pass some information between unmap and move, the original unused dst->mapping and dst->private are used. Link: https://lkml.kernel.org/r/20230213123444.155149-5-ying.huang@xxxxxxxxx Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx> Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> Reviewed-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx> Cc: Zi Yan <ziy@xxxxxxxxxx> Cc: Yang Shi <shy828301@xxxxxxxxx> Cc: Oscar Salvador <osalvador@xxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Bharata B Rao <bharata@xxxxxxx> Cc: Alistair Popple <apopple@xxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Stable-dep-of: 35e41024c4c2 ("vmscan,migrate: fix page count imbalance on node stats when demoting pages") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- include/linux/migrate.h | 1 + mm/migrate.c | 169 ++++++++++++++++++++++++++++++---------- 2 files changed, 129 insertions(+), 41 deletions(-) diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 3ef77f52a4f04..7376074f2e1e3 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -18,6 +18,7 @@ struct migration_target_control; * - zero on page migration success; */ #define MIGRATEPAGE_SUCCESS 0 +#define MIGRATEPAGE_UNMAP 1 /** * struct movable_operations - Driver page migration diff --git a/mm/migrate.c b/mm/migrate.c index 40ae91e1a026b..46a1476e188c3 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1011,11 +1011,53 @@ static int move_to_new_folio(struct folio *dst, struct folio *src, return rc; } -static int __unmap_and_move(struct folio *src, struct folio *dst, +/* + * To record some information during migration, we use some unused + * fields (mapping and private) of struct folio of the newly allocated + * destination folio. This is safe because nobody is using them + * except us. + */ +static void __migrate_folio_record(struct folio *dst, + unsigned long page_was_mapped, + struct anon_vma *anon_vma) +{ + dst->mapping = (void *)anon_vma; + dst->private = (void *)page_was_mapped; +} + +static void __migrate_folio_extract(struct folio *dst, + int *page_was_mappedp, + struct anon_vma **anon_vmap) +{ + *anon_vmap = (void *)dst->mapping; + *page_was_mappedp = (unsigned long)dst->private; + dst->mapping = NULL; + dst->private = NULL; +} + +/* Cleanup src folio upon migration success */ +static void migrate_folio_done(struct folio *src, + enum migrate_reason reason) +{ + /* + * Compaction can migrate also non-LRU pages which are + * not accounted to NR_ISOLATED_*. They can be recognized + * as __PageMovable + */ + if (likely(!__folio_test_movable(src))) + mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON + + folio_is_file_lru(src), -folio_nr_pages(src)); + + if (reason != MR_MEMORY_FAILURE) + /* We release the page in page_handle_poison. */ + folio_put(src); +} + +static int __migrate_folio_unmap(struct folio *src, struct folio *dst, int force, enum migrate_mode mode) { int rc = -EAGAIN; - bool page_was_mapped = false; + int page_was_mapped = 0; struct anon_vma *anon_vma = NULL; bool is_lru = !__PageMovable(&src->page); @@ -1091,8 +1133,8 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, goto out_unlock; if (unlikely(!is_lru)) { - rc = move_to_new_folio(dst, src, mode); - goto out_unlock_both; + __migrate_folio_record(dst, page_was_mapped, anon_vma); + return MIGRATEPAGE_UNMAP; } /* @@ -1117,11 +1159,42 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, VM_BUG_ON_FOLIO(folio_test_anon(src) && !folio_test_ksm(src) && !anon_vma, src); try_to_migrate(src, 0); - page_was_mapped = true; + page_was_mapped = 1; } - if (!folio_mapped(src)) - rc = move_to_new_folio(dst, src, mode); + if (!folio_mapped(src)) { + __migrate_folio_record(dst, page_was_mapped, anon_vma); + return MIGRATEPAGE_UNMAP; + } + + if (page_was_mapped) + remove_migration_ptes(src, src, false); + +out_unlock_both: + folio_unlock(dst); +out_unlock: + /* Drop an anon_vma reference if we took one */ + if (anon_vma) + put_anon_vma(anon_vma); + folio_unlock(src); +out: + + return rc; +} + +static int __migrate_folio_move(struct folio *src, struct folio *dst, + enum migrate_mode mode) +{ + int rc; + int page_was_mapped = 0; + struct anon_vma *anon_vma = NULL; + bool is_lru = !__PageMovable(&src->page); + + __migrate_folio_extract(dst, &page_was_mapped, &anon_vma); + + rc = move_to_new_folio(dst, src, mode); + if (unlikely(!is_lru)) + goto out_unlock_both; /* * When successful, push dst to LRU immediately: so that if it @@ -1144,12 +1217,10 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, out_unlock_both: folio_unlock(dst); -out_unlock: /* Drop an anon_vma reference if we took one */ if (anon_vma) put_anon_vma(anon_vma); folio_unlock(src); -out: /* * If migration is successful, decrease refcount of dst, * which will not free the page because new page owner increased @@ -1161,19 +1232,15 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, return rc; } -/* - * Obtain the lock on folio, remove all ptes and migrate the folio - * to the newly allocated folio in dst. - */ -static int unmap_and_move(new_page_t get_new_page, - free_page_t put_new_page, - unsigned long private, struct folio *src, - int force, enum migrate_mode mode, - enum migrate_reason reason, - struct list_head *ret) +/* Obtain the lock on page, remove all ptes. */ +static int migrate_folio_unmap(new_page_t get_new_page, free_page_t put_new_page, + unsigned long private, struct folio *src, + struct folio **dstp, int force, + enum migrate_mode mode, enum migrate_reason reason, + struct list_head *ret) { struct folio *dst; - int rc = MIGRATEPAGE_SUCCESS; + int rc = MIGRATEPAGE_UNMAP; struct page *newpage = NULL; if (!thp_migration_supported() && folio_test_transhuge(src)) @@ -1184,20 +1251,49 @@ static int unmap_and_move(new_page_t get_new_page, folio_clear_active(src); folio_clear_unevictable(src); /* free_pages_prepare() will clear PG_isolated. */ - goto out; + list_del(&src->lru); + migrate_folio_done(src, reason); + return MIGRATEPAGE_SUCCESS; } newpage = get_new_page(&src->page, private); if (!newpage) return -ENOMEM; dst = page_folio(newpage); + *dstp = dst; dst->private = NULL; - rc = __unmap_and_move(src, dst, force, mode); + rc = __migrate_folio_unmap(src, dst, force, mode); + if (rc == MIGRATEPAGE_UNMAP) + return rc; + + /* + * A folio that has not been unmapped will be restored to + * right list unless we want to retry. + */ + if (rc != -EAGAIN) + list_move_tail(&src->lru, ret); + + if (put_new_page) + put_new_page(&dst->page, private); + else + folio_put(dst); + + return rc; +} + +/* Migrate the folio to the newly allocated folio in dst. */ +static int migrate_folio_move(free_page_t put_new_page, unsigned long private, + struct folio *src, struct folio *dst, + enum migrate_mode mode, enum migrate_reason reason, + struct list_head *ret) +{ + int rc; + + rc = __migrate_folio_move(src, dst, mode); if (rc == MIGRATEPAGE_SUCCESS) set_page_owner_migrate_reason(&dst->page, reason); -out: if (rc != -EAGAIN) { /* * A folio that has been migrated has all references @@ -1213,20 +1309,7 @@ static int unmap_and_move(new_page_t get_new_page, * we want to retry. */ if (rc == MIGRATEPAGE_SUCCESS) { - /* - * Compaction can migrate also non-LRU folios which are - * not accounted to NR_ISOLATED_*. They can be recognized - * as __folio_test_movable - */ - if (likely(!__folio_test_movable(src))) - mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON + - folio_is_file_lru(src), -folio_nr_pages(src)); - - if (reason != MR_MEMORY_FAILURE) - /* - * We release the folio in page_handle_poison. - */ - folio_put(src); + migrate_folio_done(src, reason); } else { if (rc != -EAGAIN) list_add_tail(&src->lru, ret); @@ -1518,7 +1601,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, int pass = 0; bool is_large = false; bool is_thp = false; - struct folio *folio, *folio2; + struct folio *folio, *folio2, *dst = NULL; int rc, nr_pages; LIST_HEAD(split_folios); bool nosplit = (reason == MR_NUMA_MISPLACED); @@ -1545,9 +1628,13 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, cond_resched(); - rc = unmap_and_move(get_new_page, put_new_page, - private, folio, pass > 2, mode, - reason, ret_folios); + rc = migrate_folio_unmap(get_new_page, put_new_page, private, + folio, &dst, pass > 2, mode, + reason, ret_folios); + if (rc == MIGRATEPAGE_UNMAP) + rc = migrate_folio_move(put_new_page, private, + folio, dst, mode, + reason, ret_folios); /* * The rules are: * Success: folio will be freed -- 2.43.0
