From ebe75e4751063dce6f61b579b43de86dcf7b7462 Mon Sep 17 00:00:00 2001 From: Huang Ying Date: Mon, 13 Feb 2023 20:34:42 +0800 Subject: migrate_pages: share more code between _unmap and _move This is a code cleanup patch to reduce the duplicated code between the _unmap and _move stages of migrate_pages(). No functionality change is expected. Link: https://lkml.kernel.org/r/20230213123444.155149-8-ying.huang@intel.com Signed-off-by: "Huang, Ying" Cc: Zi Yan Cc: Yang Shi Cc: Baolin Wang Cc: Oscar Salvador Cc: Matthew Wilcox Cc: Bharata B Rao Cc: Alistair Popple Cc: Xin Hao Cc: Minchan Kim Cc: Mike Kravetz Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Signed-off-by: Andrew Morton --- mm/migrate.c | 207 ++++++++++++++++++++++++----------------------------------- 1 file changed, 85 insertions(+), 122 deletions(-) (limited to 'mm') diff --git a/mm/migrate.c b/mm/migrate.c index 0c7488ebe248..00713ccb6643 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1055,6 +1055,7 @@ static void __migrate_folio_extract(struct folio *dst, static void migrate_folio_undo_src(struct folio *src, int page_was_mapped, struct anon_vma *anon_vma, + bool locked, struct list_head *ret) { if (page_was_mapped) @@ -1062,16 +1063,20 @@ static void migrate_folio_undo_src(struct folio *src, /* Drop an anon_vma reference if we took one */ if (anon_vma) put_anon_vma(anon_vma); - folio_unlock(src); - list_move_tail(&src->lru, ret); + if (locked) + folio_unlock(src); + if (ret) + list_move_tail(&src->lru, ret); } /* Restore the destination folio to the original state upon failure */ static void migrate_folio_undo_dst(struct folio *dst, + bool locked, free_page_t put_new_page, unsigned long private) { - folio_unlock(dst); + if (locked) + folio_unlock(dst); if (put_new_page) put_new_page(&dst->page, private); else @@ -1096,13 +1101,42 @@ static void migrate_folio_done(struct folio *src, folio_put(src); } -static int __migrate_folio_unmap(struct folio *src, struct folio *dst, int force, - bool avoid_force_lock, enum migrate_mode mode) +/* 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, bool avoid_force_lock, + enum migrate_mode mode, enum migrate_reason reason, + struct list_head *ret) { + struct folio *dst; int rc = -EAGAIN; + struct page *newpage = NULL; int page_was_mapped = 0; struct anon_vma *anon_vma = NULL; bool is_lru = !__PageMovable(&src->page); + bool locked = false; + bool dst_locked = false; + + if (!thp_migration_supported() && folio_test_transhuge(src)) + return -ENOSYS; + + if (folio_ref_count(src) == 1) { + /* Folio was freed from under us. So we are done. */ + folio_clear_active(src); + folio_clear_unevictable(src); + /* free_pages_prepare() will clear PG_isolated. */ + 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; if (!folio_trylock(src)) { if (!force || mode == MIGRATE_ASYNC) @@ -1137,6 +1171,7 @@ static int __migrate_folio_unmap(struct folio *src, struct folio *dst, int force folio_lock(src); } + locked = true; if (folio_test_writeback(src)) { /* @@ -1151,10 +1186,10 @@ static int __migrate_folio_unmap(struct folio *src, struct folio *dst, int force break; default: rc = -EBUSY; - goto out_unlock; + goto out; } if (!force) - goto out_unlock; + goto out; folio_wait_writeback(src); } @@ -1184,7 +1219,8 @@ static int __migrate_folio_unmap(struct folio *src, struct folio *dst, int force * This is much like races on refcount of oldpage: just don't BUG(). */ if (unlikely(!folio_trylock(dst))) - goto out_unlock; + goto out; + dst_locked = true; if (unlikely(!is_lru)) { __migrate_folio_record(dst, page_was_mapped, anon_vma); @@ -1206,7 +1242,7 @@ static int __migrate_folio_unmap(struct folio *src, struct folio *dst, int force if (!src->mapping) { if (folio_test_private(src)) { try_to_free_buffers(src); - goto out_unlock_both; + goto out; } } else if (folio_mapped(src)) { /* Establish migration ptes */ @@ -1221,73 +1257,25 @@ static int __migrate_folio_unmap(struct folio *src, struct folio *dst, int force 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; -} - -/* 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, bool avoid_force_lock, - enum migrate_mode mode, enum migrate_reason reason, - struct list_head *ret) -{ - struct folio *dst; - int rc = MIGRATEPAGE_UNMAP; - struct page *newpage = NULL; - - if (!thp_migration_supported() && folio_test_transhuge(src)) - return -ENOSYS; - - if (folio_ref_count(src) == 1) { - /* Folio was freed from under us. So we are done. */ - folio_clear_active(src); - folio_clear_unevictable(src); - /* free_pages_prepare() will clear PG_isolated. */ - 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 = __migrate_folio_unmap(src, dst, force, avoid_force_lock, 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 && rc != -EDEADLOCK) - list_move_tail(&src->lru, ret); + if (rc == -EAGAIN || rc == -EDEADLOCK) + ret = NULL; - if (put_new_page) - put_new_page(&dst->page, private); - else - folio_put(dst); + migrate_folio_undo_src(src, page_was_mapped, anon_vma, locked, ret); + migrate_folio_undo_dst(dst, dst_locked, put_new_page, private); return rc; } -static int __migrate_folio_move(struct folio *src, struct folio *dst, - enum migrate_mode mode) +/* 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; int page_was_mapped = 0; @@ -1300,12 +1288,8 @@ static int __migrate_folio_move(struct folio *src, struct folio *dst, list_del(&dst->lru); rc = move_to_new_folio(dst, src, mode); - - if (rc == -EAGAIN) { - list_add(&dst->lru, prev); - __migrate_folio_record(dst, page_was_mapped, anon_vma); - return rc; - } + if (rc) + goto out; if (unlikely(!is_lru)) goto out_unlock_both; @@ -1319,70 +1303,49 @@ static int __migrate_folio_move(struct folio *src, struct folio *dst, * unsuccessful, and other cases when a page has been temporarily * isolated from the unevictable LRU: but this case is the easiest. */ - if (rc == MIGRATEPAGE_SUCCESS) { - folio_add_lru(dst); - if (page_was_mapped) - lru_add_drain(); - } + folio_add_lru(dst); + if (page_was_mapped) + lru_add_drain(); if (page_was_mapped) - remove_migration_ptes(src, - rc == MIGRATEPAGE_SUCCESS ? dst : src, false); + remove_migration_ptes(src, dst, false); out_unlock_both: folio_unlock(dst); - /* Drop an anon_vma reference if we took one */ - if (anon_vma) - put_anon_vma(anon_vma); - folio_unlock(src); + set_page_owner_migrate_reason(&dst->page, reason); /* * If migration is successful, decrease refcount of dst, * which will not free the page because new page owner increased * refcounter. */ - if (rc == MIGRATEPAGE_SUCCESS) - 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); - - if (rc != -EAGAIN) { - /* - * A folio that has been migrated has all references - * removed and will be freed. A folio that has not been - * migrated will have kept its references and be restored. - */ - list_del(&src->lru); - } + folio_put(dst); /* - * If migration is successful, releases reference grabbed during - * isolation. Otherwise, restore the folio to right list unless - * we want to retry. + * A folio that has been migrated has all references removed + * and will be freed. */ - if (rc == MIGRATEPAGE_SUCCESS) { - migrate_folio_done(src, reason); - } else if (rc != -EAGAIN) { - list_add_tail(&src->lru, ret); + list_del(&src->lru); + /* Drop an anon_vma reference if we took one */ + if (anon_vma) + put_anon_vma(anon_vma); + folio_unlock(src); + migrate_folio_done(src, reason); - if (put_new_page) - put_new_page(&dst->page, private); - else - folio_put(dst); + return rc; +out: + /* + * A folio that has not been migrated will be restored to + * right list unless we want to retry. + */ + if (rc == -EAGAIN) { + list_add(&dst->lru, prev); + __migrate_folio_record(dst, page_was_mapped, anon_vma); + return rc; } + migrate_folio_undo_src(src, page_was_mapped, anon_vma, true, ret); + migrate_folio_undo_dst(dst, true, put_new_page, private); + return rc; } @@ -1918,9 +1881,9 @@ out: __migrate_folio_extract(dst, &page_was_mapped, &anon_vma); migrate_folio_undo_src(folio, page_was_mapped, anon_vma, - ret_folios); + true, ret_folios); list_del(&dst->lru); - migrate_folio_undo_dst(dst, put_new_page, private); + migrate_folio_undo_dst(dst, true, put_new_page, private); dst = dst2; dst2 = list_next_entry(dst, lru); } -- cgit v1.2.3