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 A6B85C41513 for ; Tue, 15 Aug 2023 08:39:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235699AbjHOIjB (ORCPT ); Tue, 15 Aug 2023 04:39:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43772 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235768AbjHOIir (ORCPT ); Tue, 15 Aug 2023 04:38:47 -0400 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9717F133 for ; Tue, 15 Aug 2023 01:38:45 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045170;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0VprJQL7_1692088721; Received: from 30.97.48.59(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VprJQL7_1692088721) by smtp.aliyun-inc.com; Tue, 15 Aug 2023 16:38:42 +0800 Message-ID: Date: Tue, 15 Aug 2023 16:38:43 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Subject: Re: [PATCH 4/9] mm/compaction: simplify pfn iteration in isolate_freepages_range To: Kemeng Shi , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mgorman@techsingularity.net, david@redhat.com References: <20230805110711.2975149-1-shikemeng@huaweicloud.com> <20230805110711.2975149-5-shikemeng@huaweicloud.com> From: Baolin Wang In-Reply-To: <20230805110711.2975149-5-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 8/5/2023 7:07 PM, Kemeng Shi wrote: > We call isolate_freepages_block in strict mode, continuous pages in > pageblock will be isolated if isolate_freepages_block successed. > Then pfn + isolated will point to start of next pageblock to scan > no matter how many pageblocks are isolated in isolate_freepages_block. > Use pfn + isolated as start of next pageblock to scan to simplify the > iteration. IIUC, the isolate_freepages_block() can isolate high-order free pages, which means the pfn + isolated can be larger than the block_end_pfn. So in your patch, the 'block_start_pfn' and 'block_end_pfn' can be in different pageblocks, that will break pageblock_pfn_to_page(). > > Signed-off-by: Kemeng Shi > --- > mm/compaction.c | 14 ++------------ > 1 file changed, 2 insertions(+), 12 deletions(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index 684f6e6cd8bc..8d7d38073d30 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -733,21 +733,11 @@ isolate_freepages_range(struct compact_control *cc, > block_end_pfn = pageblock_end_pfn(pfn); > > for (; pfn < end_pfn; pfn += isolated, > - block_start_pfn = block_end_pfn, > - block_end_pfn += pageblock_nr_pages) { > + block_start_pfn = pfn, > + block_end_pfn = pfn + pageblock_nr_pages) { > /* Protect pfn from changing by isolate_freepages_block */ > unsigned long isolate_start_pfn = pfn; > > - /* > - * pfn could pass the block_end_pfn if isolated freepage > - * is more than pageblock order. In this case, we adjust > - * scanning range to right one. > - */ > - if (pfn >= block_end_pfn) { > - block_start_pfn = pageblock_start_pfn(pfn); > - block_end_pfn = pageblock_end_pfn(pfn); > - } > - > block_end_pfn = min(block_end_pfn, end_pfn); > > if (!pageblock_pfn_to_page(block_start_pfn,