From nobody Wed Feb 11 22:54:49 2026 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 E6ECCC7619A for ; Wed, 12 Apr 2023 10:46:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230044AbjDLKqT (ORCPT ); Wed, 12 Apr 2023 06:46:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230045AbjDLKqD (ORCPT ); Wed, 12 Apr 2023 06:46:03 -0400 Received: from out30-100.freemail.mail.aliyun.com (out30-100.freemail.mail.aliyun.com [115.124.30.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C8476EAD for ; Wed, 12 Apr 2023 03:45:44 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046056;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0Vfw8Fy8_1681296340; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Vfw8Fy8_1681296340) by smtp.aliyun-inc.com; Wed, 12 Apr 2023 18:45:41 +0800 From: Baolin Wang To: akpm@linux-foundation.org Cc: mgorman@techsingularity.net, vbabka@suse.cz, mhocko@suse.com, david@redhat.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm/page_alloc: consider pfn holes after pfn_valid() in __pageblock_pfn_to_page() Date: Wed, 12 Apr 2023 18:45:31 +0800 Message-Id: <62e231a8f2e50c04dcadc7a0cfaa6dea5ce1ec05.1681296022.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Now the __pageblock_pfn_to_page() is used by set_zone_contiguous(), which checks whether the given zone contains holes, and uses pfn_valid() to check if the end pfn is valid. However pfn_valid() can not make sure the end pfn is not a hole if the size of a pageblock is larger than the size of a sub-mem_section, since the struct page getting by pfn_to_page() may represent a hole or an unusable page frame, which may cause incorrect zone contiguous is set. Though another user of pageblock_pfn_to_page() in compaction seems work well now, it is better to avoid scanning or touching these offline pfns. So like commit 2d070eab2e82 ("mm: consider zone which is not fully populated to have holes"), we should also use pfn_to_online_page() for the end pfn to make sure it is a valid pfn with usable page frame. Meanwhile the pfn_valid() for end pfn can be dropped now. Moreover we've already used pfn_to_online_page() for start pfn to make sure it is online and valid, so the pfn_valid() for the start pfn is unnecessary, drop it. Signed-off-by: Baolin Wang --- mm/page_alloc.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d0eb280ec7e4..8076f519c572 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1512,9 +1512,6 @@ struct page *__pageblock_pfn_to_page(unsigned long st= art_pfn, /* end_pfn is one past the range we are checking */ end_pfn--; =20 - if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn)) - return NULL; - start_page =3D pfn_to_online_page(start_pfn); if (!start_page) return NULL; @@ -1522,7 +1519,9 @@ struct page *__pageblock_pfn_to_page(unsigned long st= art_pfn, if (page_zone(start_page) !=3D zone) return NULL; =20 - end_page =3D pfn_to_page(end_pfn); + end_page =3D pfn_to_online_page(end_pfn); + if (!end_page) + return NULL; =20 /* This gives a shorter code than deriving page_zone(end_page) */ if (page_zone_id(start_page) !=3D page_zone_id(end_page)) --=20 2.27.0