From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 618A5C001DF for ; Tue, 1 Aug 2023 02:19:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F37E72800C5; Mon, 31 Jul 2023 22:19:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EE87328007A; Mon, 31 Jul 2023 22:19:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DB0822800C5; Mon, 31 Jul 2023 22:19:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id CAF5028007A for ; Mon, 31 Jul 2023 22:19:45 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id A2C641C9917 for ; 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And >> then: >> 1. We check if we mark the page block skip for exclusive access in >> isolate_migratepages_block by test if next migrate pfn is still in last >> isolated page block. If so, we will set finish_pageblock to do the rescan. >> 2. We check if a full cc->order block is scanned by test if last scan range >> passes the cc->order block boundary. If so, we flush the pages were freed. >> >> We treat cc->migrate_pfn before isolate_migratepages as the start pfn of >> last isolated page range. However, we always align migrate_pfn to page block >> or move to another page block in fast_find_migrateblock or in linearly scan >> forward in isolate_migratepages before do page isolation in >> isolate_migratepages_block. > > Right. But can you describe the impact in detail if the last_migrated_pfn is not set correctly? For example, this will result in rescan not being set correctly to miss a pageblock's rescanning. > > Otherwise looks good to me. > Sure, the impact will be added in next version. Thanks! >> Update last_migrated_pfn with pageblock_start_pfn(cc->migrate_pfn - 1) >> after scan to correctly set start pfn of last isolated page range. > Signed-off-by: Kemeng Shi >> --- >>   mm/compaction.c | 3 ++- >>   1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/mm/compaction.c b/mm/compaction.c >> index ce7841363b12..fb250c6b2b6e 100644 >> --- a/mm/compaction.c >> +++ b/mm/compaction.c >> @@ -2482,7 +2482,8 @@ compact_zone(struct compact_control *cc, struct capture_control *capc) >>               goto check_drain; >>           case ISOLATE_SUCCESS: >>               update_cached = false; >> -            last_migrated_pfn = iteration_start_pfn; >> +            last_migrated_pfn = max(cc->zone->zone_start_pfn, >> +                pageblock_start_pfn(cc->migrate_pfn - 1)); >>           } >>             err = migrate_pages(&cc->migratepages, compaction_alloc, > -- Best wishes Kemeng Shi