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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7F29C001DF for ; Wed, 2 Aug 2023 11:20:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234136AbjHBLUF (ORCPT ); Wed, 2 Aug 2023 07:20:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48738 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234121AbjHBLUD (ORCPT ); Wed, 2 Aug 2023 07:20:03 -0400 Received: from out30-97.freemail.mail.aliyun.com (out30-97.freemail.mail.aliyun.com [115.124.30.97]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E45E2139 for ; Wed, 2 Aug 2023 04:20:01 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045168;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0VouwrhT_1690975197; Received: from 30.97.48.77(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VouwrhT_1690975197) by smtp.aliyun-inc.com; Wed, 02 Aug 2023 19:19:58 +0800 Message-ID: <026aaebd-ceb3-0659-8f54-2ec3cd81b5df@linux.alibaba.com> Date: Wed, 2 Aug 2023 19:20:24 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v2 2/8] mm/compaction: correct last_migrated_pfn update in compact_zone To: Kemeng Shi , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mgorman@techsingularity.net, david@redhat.com References: <20230802093741.2333325-1-shikemeng@huaweicloud.com> <20230802093741.2333325-3-shikemeng@huaweicloud.com> From: Baolin Wang In-Reply-To: <20230802093741.2333325-3-shikemeng@huaweicloud.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/2/2023 5:37 PM, Kemeng Shi wrote: > We record start pfn of last isolated page block with last_migrated_pfn. 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. > > Update last_migrated_pfn with pageblock_start_pfn(cc->migrate_pfn - 1) > after scan to correctly set start pfn of last isolated page range. To > avoid that: > 1. Miss a rescan with finish_pageblock set as last_migrate_pfn does not > point to right pageblock and the migrate will not be in pageblock of > last_migrate_pfn as it should be. > 2. Wrongly issue flush by test cc->order block boundary with wrong > last_migrate_pfn. > > Signed-off-by: Kemeng Shi LGTM. Reviewed-by: Baolin Wang > --- > mm/compaction.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index a8cea916df9d..ec3a96b7afce 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -2487,7 +2487,8 @@ 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,