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 55F42C001DE for ; Tue, 1 Aug 2023 02:34:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232132AbjHACel (ORCPT ); Mon, 31 Jul 2023 22:34:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34052 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229648AbjHACej (ORCPT ); Mon, 31 Jul 2023 22:34:39 -0400 Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6765EF1 for ; Mon, 31 Jul 2023 19:34:38 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046049;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0VojAOgJ_1690857274; Received: from 30.97.48.66(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VojAOgJ_1690857274) by smtp.aliyun-inc.com; Tue, 01 Aug 2023 10:34:35 +0800 Message-ID: <8b95b1c6-62a9-eff6-4c52-9112834e69a6@linux.alibaba.com> Date: Tue, 1 Aug 2023 10:35:02 +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 3/8] mm/compaction: skip page block marked skip in isolate_migratepages_block To: Kemeng Shi , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, mgorman@techsingularity.net, willy@infradead.org, david@redhat.com References: <20230728171037.2219226-1-shikemeng@huaweicloud.com> <20230728171037.2219226-4-shikemeng@huaweicloud.com> From: Baolin Wang In-Reply-To: <20230728171037.2219226-4-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 7/29/2023 1:10 AM, Kemeng Shi wrote: > Move migrate_pfn to page block end when block is marked skip to avoid > unnecessary scan retry of that block from upper caller. > For example, compact_zone may wrongly rescan skip page block with > finish_pageblock set as following: > 1. cc->migrate point to the start of page block > 2. compact_zone record last_migrated_pfn to cc->migrate > 3. compact_zone->isolate_migratepages->isolate_migratepages_block tries to > scan the block. The low_pfn maybe moved forward to middle of block because > of free pages at beginning of block. > 4. we find first lru page could be isolated but block was exclusive marked > skip. > 5. abort isolate_migratepages_block and make cc->migrate_pfn point to > found lru page at middle of block. > 6. compact_zone find cc->migrate_pfn and last_migrated_pfn are in the same > block and wrongly rescan the block with finish_pageblock set. Good catch. Reviewed-by: Baolin Wang > Signed-off-by: Kemeng Shi > --- > mm/compaction.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/compaction.c b/mm/compaction.c > index fb250c6b2b6e..ad535f880c70 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1123,6 +1123,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > skip_updated = true; > if (test_and_set_skip(cc, valid_page) && > !cc->finish_pageblock) { > + low_pfn = end_pfn; > goto isolate_abort; > } > }