diff options
| -rw-r--r-- | mm/migrate.c | 69 |
1 files changed, 26 insertions, 43 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 98f1c11197a8..f348e0a7b1df 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1112,7 +1112,7 @@ static void migrate_folio_done(struct folio *src, /* 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, + struct folio **dstp, int force, enum migrate_mode mode, enum migrate_reason reason, struct list_head *ret) { @@ -1163,17 +1163,6 @@ static int migrate_folio_unmap(new_page_t get_new_page, free_page_t put_new_page if (current->flags & PF_MEMALLOC) goto out; - /* - * We have locked some folios and are going to wait to lock - * this folio. To avoid a potential deadlock, let's bail - * out and not do that. The locked folios will be moved and - * unlocked, then we can wait to lock this folio. - */ - if (avoid_force_lock) { - rc = -EDEADLOCK; - goto out; - } - folio_lock(src); } locked = true; @@ -1253,7 +1242,7 @@ static int migrate_folio_unmap(new_page_t get_new_page, free_page_t put_new_page /* Establish migration ptes */ VM_BUG_ON_FOLIO(folio_test_anon(src) && !folio_test_ksm(src) && !anon_vma, src); - try_to_migrate(src, TTU_BATCH_FLUSH); + try_to_migrate(src, mode == MIGRATE_ASYNC ? TTU_BATCH_FLUSH : 0); page_was_mapped = 1; } @@ -1267,7 +1256,7 @@ out: * A folio that has not been unmapped will be restored to * right list unless we want to retry. */ - if (rc == -EAGAIN || rc == -EDEADLOCK) + if (rc == -EAGAIN) ret = NULL; migrate_folio_undo_src(src, page_was_mapped, anon_vma, locked, ret); @@ -1618,6 +1607,11 @@ static int migrate_hugetlbs(struct list_head *from, new_page_t get_new_page, /* * migrate_pages_batch() first unmaps folios in the from list as many as * possible, then move the unmapped folios. + * + * We only batch migration if mode == MIGRATE_ASYNC to avoid to wait a + * lock or bit when we have locked more than one folio. Which may cause + * deadlock (e.g., for loop device). So, if mode != MIGRATE_ASYNC, the + * length of the from list must be <= 1. */ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, free_page_t put_new_page, unsigned long private, @@ -1640,11 +1634,11 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, LIST_HEAD(dst_folios); bool nosplit = (reason == MR_NUMA_MISPLACED); bool no_split_folio_counting = false; - bool avoid_force_lock; + VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC && + !list_empty(from) && !list_is_singular(from)); retry: rc_saved = 0; - avoid_force_lock = false; retry = 1; for (pass = 0; pass < NR_MAX_MIGRATE_PAGES_RETRY && (retry || large_retry); @@ -1689,15 +1683,14 @@ retry: } rc = migrate_folio_unmap(get_new_page, put_new_page, private, - folio, &dst, pass > 2, avoid_force_lock, - mode, reason, ret_folios); + folio, &dst, pass > 2, mode, + reason, ret_folios); /* * The rules are: * Success: folio will be freed * Unmap: folio will be put on unmap_folios list, * dst folio put on dst_folios list * -EAGAIN: stay on the from list - * -EDEADLOCK: stay on the from list * -ENOMEM: stay on the from list * Other errno: put on ret_folios list */ @@ -1749,14 +1742,6 @@ retry: goto out; else goto move; - case -EDEADLOCK: - /* - * The folio cannot be locked for potential deadlock. - * Go move (and unlock) all locked folios. Then we can - * try again. - */ - rc_saved = rc; - goto move; case -EAGAIN: if (is_large) { large_retry++; @@ -1771,11 +1756,6 @@ retry: stats->nr_thp_succeeded += is_thp; break; case MIGRATEPAGE_UNMAP: - /* - * We have locked some folios, don't force lock - * to avoid deadlock. - */ - avoid_force_lock = true; list_move_tail(&folio->lru, &unmap_folios); list_add_tail(&dst->lru, &dst_folios); break; @@ -1900,17 +1880,15 @@ out: */ list_splice_init(from, ret_folios); list_splice_init(&split_folios, from); + /* + * Force async mode to avoid to wait lock or bit when we have + * locked more than one folios. + */ + mode = MIGRATE_ASYNC; no_split_folio_counting = true; goto retry; } - /* - * We have unlocked all locked folios, so we can force lock now, let's - * try again. - */ - if (rc == -EDEADLOCK) - goto retry; - return rc; } @@ -1945,7 +1923,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, enum migrate_mode mode, int reason, unsigned int *ret_succeeded) { int rc, rc_gather; - int nr_pages; + int nr_pages, batch; struct folio *folio, *folio2; LIST_HEAD(folios); LIST_HEAD(ret_folios); @@ -1959,6 +1937,11 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, mode, reason, &stats, &ret_folios); if (rc_gather < 0) goto out; + + if (mode == MIGRATE_ASYNC) + batch = NR_MAX_BATCHED_MIGRATION; + else + batch = 1; again: nr_pages = 0; list_for_each_entry_safe(folio, folio2, from, lru) { @@ -1969,11 +1952,11 @@ again: } nr_pages += folio_nr_pages(folio); - if (nr_pages > NR_MAX_BATCHED_MIGRATION) + if (nr_pages >= batch) break; } - if (nr_pages > NR_MAX_BATCHED_MIGRATION) - list_cut_before(&folios, from, &folio->lru); + if (nr_pages >= batch) + list_cut_before(&folios, from, &folio2->lru); else list_splice_init(from, &folios); rc = migrate_pages_batch(&folios, get_new_page, put_new_page, private, |