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09 Jan 2023 23:53:47 -0800 From: Huang Ying To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , Zi Yan , Yang Shi , Baolin Wang , Oscar Salvador , Matthew Wilcox , Bharata B Rao , Alistair Popple , haoxin Subject: [PATCH -v2 5/9] migrate_pages: batch _unmap and _move Date: Tue, 10 Jan 2023 15:53:23 +0800 Message-Id: <20230110075327.590514-6-ying.huang@intel.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20230110075327.590514-1-ying.huang@intel.com> References: <20230110075327.590514-1-ying.huang@intel.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 48A2EC0010 X-Stat-Signature: n3xz1j65e98r76ubnmuuew5m9j76uo3m X-HE-Tag: 1673337231-832369 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In this patch the _unmap and _move stage of the folio migration is batched. That for, previously, it is, for each folio _unmap() _move() Now, it is, for each folio _unmap() for each folio _move() Based on this, we can batch the TLB flushing and use some hardware accelerator to copy folios between batched _unmap and batched _move stages. 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: haoxin --- mm/migrate.c | 205 +++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 181 insertions(+), 24 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 4c35c2a49574..2983662cff75 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1033,6 +1033,33 @@ static void __migrate_folio_extract(struct folio *dst, dst->private = NULL; } +/* Restore the source folio to the original state upon failure */ +static void migrate_folio_undo_src(struct folio *src, + int page_was_mapped, + struct anon_vma *anon_vma, + struct list_head *ret) +{ + if (page_was_mapped) + remove_migration_ptes(src, src, false); + /* 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); +} + +/* Restore the destination folio to the original state upon failure */ +static void migrate_folio_undo_dst(struct folio *dst, + free_page_t put_new_page, + unsigned long private) +{ + folio_unlock(dst); + if (put_new_page) + put_new_page(&dst->page, private); + else + folio_put(dst); +} + /* Cleanup src folio upon migration success */ static void migrate_folio_done(struct folio *src, enum migrate_reason reason) @@ -1052,7 +1079,7 @@ static void migrate_folio_done(struct folio *src, } static int __migrate_folio_unmap(struct folio *src, struct folio *dst, - int force, enum migrate_mode mode) + int force, bool force_lock, enum migrate_mode mode) { int rc = -EAGAIN; int page_was_mapped = 0; @@ -1079,6 +1106,17 @@ static int __migrate_folio_unmap(struct folio *src, struct folio *dst, if (current->flags & PF_MEMALLOC) goto out; + /* + * We have locked some folios, to avoid deadlock, we cannot + * lock the folio synchronously. Go out to process (and + * unlock) all the locked folios. Then we can lock the folio + * synchronously. + */ + if (!force_lock) { + rc = -EDEADLOCK; + goto out; + } + folio_lock(src); } @@ -1192,6 +1230,8 @@ static int __migrate_folio_move(struct folio *src, struct folio *dst, rc = move_to_new_folio(dst, src, mode); + if (rc != -EAGAIN) + list_del(&dst->lru); /* * When successful, push dst to LRU immediately: so that if it * turns out to be an mlocked page, remove_migration_ptes() will @@ -1207,6 +1247,11 @@ static int __migrate_folio_move(struct folio *src, struct folio *dst, lru_add_drain(); } + if (rc == -EAGAIN) { + __migrate_folio_record(dst, page_was_mapped, anon_vma); + return rc; + } + if (page_was_mapped) remove_migration_ptes(src, rc == MIGRATEPAGE_SUCCESS ? dst : src, false); @@ -1230,7 +1275,7 @@ static int __migrate_folio_move(struct folio *src, struct folio *dst, /* 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, + struct folio **dstp, int force, bool force_lock, enum migrate_mode mode, enum migrate_reason reason, struct list_head *ret) { @@ -1258,7 +1303,7 @@ static int migrate_folio_unmap(new_page_t get_new_page, free_page_t put_new_page *dstp = dst; dst->private = NULL; - rc = __migrate_folio_unmap(src, dst, force, mode); + rc = __migrate_folio_unmap(src, dst, force, force_lock, mode); if (rc == MIGRATEPAGE_UNMAP) return rc; @@ -1267,7 +1312,7 @@ static int migrate_folio_unmap(new_page_t get_new_page, free_page_t put_new_page * references and be restored. */ /* restore the folio to right list. */ - if (rc != -EAGAIN) + if (rc != -EAGAIN && rc != -EDEADLOCK) list_move_tail(&src->lru, ret); if (put_new_page) @@ -1306,9 +1351,8 @@ static int migrate_folio_move(free_page_t put_new_page, unsigned long private, */ if (rc == MIGRATEPAGE_SUCCESS) { migrate_folio_done(src, reason); - } else { - if (rc != -EAGAIN) - list_add_tail(&src->lru, ret); + } else if (rc != -EAGAIN) { + list_add_tail(&src->lru, ret); if (put_new_page) put_new_page(&dst->page, private); @@ -1588,7 +1632,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, enum migrate_mode mode, int reason, struct list_head *ret_folios, struct migrate_pages_stats *stats) { - int retry = 1; + int retry; int large_retry = 1; int thp_retry = 1; int nr_failed = 0; @@ -1597,13 +1641,19 @@ 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, *dst = NULL; - int rc, nr_pages; + struct folio *folio, *folio2, *dst = NULL, *dst2; + int rc, rc_saved, nr_pages; LIST_HEAD(split_folios); + LIST_HEAD(unmap_folios); + LIST_HEAD(dst_folios); bool nosplit = (reason == MR_NUMA_MISPLACED); bool no_split_folio_counting = false; + bool force_lock; -split_folio_migration: +retry: + rc_saved = 0; + force_lock = true; + retry = 1; for (pass = 0; pass < NR_MAX_MIGRATE_PAGES_RETRY && (retry || large_retry); pass++) { @@ -1625,16 +1675,15 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, cond_resched(); 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); + folio, &dst, pass > 2, force_lock, + 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 * -ENOSYS: stay on the from list * Other errno: put on ret_folios list @@ -1669,7 +1718,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, case -ENOMEM: /* * When memory is low, don't bother to try to migrate - * other folios, just exit. + * other folios, move unmapped folios, then exit. */ if (is_large) { nr_large_failed++; @@ -1708,7 +1757,19 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, /* nr_failed isn't updated for not used */ nr_large_failed += large_retry; stats->nr_thp_failed += thp_retry; - goto out; + rc_saved = rc; + if (list_empty(&unmap_folios)) + 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++; @@ -1722,6 +1783,15 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, stats->nr_succeeded += nr_pages; stats->nr_thp_succeeded += is_thp; break; + case MIGRATEPAGE_UNMAP: + /* + * We have locked some folios, don't force lock + * to avoid deadlock. + */ + force_lock = false; + list_move_tail(&folio->lru, &unmap_folios); + list_add_tail(&dst->lru, &dst_folios); + break; default: /* * Permanent failure (-EBUSY, etc.): @@ -1745,12 +1815,95 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, nr_large_failed += large_retry; stats->nr_thp_failed += thp_retry; stats->nr_failed_pages += nr_retry_pages; +move: + retry = 1; + for (pass = 0; + pass < NR_MAX_MIGRATE_PAGES_RETRY && (retry || large_retry); + pass++) { + retry = 0; + large_retry = 0; + thp_retry = 0; + nr_retry_pages = 0; + + dst = list_first_entry(&dst_folios, struct folio, lru); + dst2 = list_next_entry(dst, lru); + list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) { + is_large = folio_test_large(folio); + is_thp = is_large && folio_test_pmd_mappable(folio); + nr_pages = folio_nr_pages(folio); + + cond_resched(); + + rc = migrate_folio_move(put_new_page, private, + folio, dst, mode, + reason, ret_folios); + /* + * The rules are: + * Success: folio will be freed + * -EAGAIN: stay on the unmap_folios list + * Other errno: put on ret_folios list + */ + switch(rc) { + case -EAGAIN: + if (is_large) { + large_retry++; + thp_retry += is_thp; + } else if (!no_split_folio_counting) { + retry++; + } + nr_retry_pages += nr_pages; + break; + case MIGRATEPAGE_SUCCESS: + stats->nr_succeeded += nr_pages; + stats->nr_thp_succeeded += is_thp; + break; + default: + if (is_large) { + nr_large_failed++; + stats->nr_thp_failed += is_thp; + } else if (!no_split_folio_counting) { + nr_failed++; + } + + stats->nr_failed_pages += nr_pages; + break; + } + dst = dst2; + dst2 = list_next_entry(dst, lru); + } + } + nr_failed += retry; + nr_large_failed += large_retry; + stats->nr_thp_failed += thp_retry; + stats->nr_failed_pages += nr_retry_pages; + + if (rc_saved) + rc = rc_saved; + else + rc = nr_failed + nr_large_failed; +out: + /* Cleanup remaining folios */ + dst = list_first_entry(&dst_folios, struct folio, lru); + dst2 = list_next_entry(dst, lru); + list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) { + int page_was_mapped = 0; + struct anon_vma *anon_vma = NULL; + + __migrate_folio_extract(dst, &page_was_mapped, &anon_vma); + migrate_folio_undo_src(folio, page_was_mapped, anon_vma, + ret_folios); + list_del(&dst->lru); + migrate_folio_undo_dst(dst, put_new_page, private); + dst = dst2; + dst2 = list_next_entry(dst, lru); + } + /* * Try to migrate split folios of fail-to-migrate large folios, no * nr_failed counting in this round, since all split folios of a * large folio is counted as 1 failure in the first round. */ - if (!list_empty(&split_folios)) { + if (rc >= 0 && !list_empty(&split_folios)) { /* * Move non-migrated folios (after NR_MAX_MIGRATE_PAGES_RETRY * retries) to ret_folios to avoid migrating them again. @@ -1758,12 +1911,16 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, list_splice_init(from, ret_folios); list_splice_init(&split_folios, from); no_split_folio_counting = true; - retry = 1; - goto split_folio_migration; + goto retry; } - rc = nr_failed + nr_large_failed; -out: + /* + * We have unlocked all locked folios, so we can force lock now, let's + * try again. + */ + if (rc == -EDEADLOCK) + goto retry; + return rc; }