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 150C0C433EF for ; Thu, 16 Jun 2022 16:20:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377391AbiFPQUe (ORCPT ); Thu, 16 Jun 2022 12:20:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232642AbiFPQU1 (ORCPT ); Thu, 16 Jun 2022 12:20:27 -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 1060D2FFD1; Thu, 16 Jun 2022 09:20:25 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046059;MF=xianting.tian@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0VGasHmk_1655396420; Received: from B-LB6YLVDL-0141.local(mailfrom:xianting.tian@linux.alibaba.com fp:SMTPD_---0VGasHmk_1655396420) by smtp.aliyun-inc.com; Fri, 17 Jun 2022 00:20:21 +0800 Subject: Re: [PATCH] mm: page_alloc: validate buddy page before using To: akpm@linux-foundation.org, ziy@nvidia.com, gregkh@linuxfoundation.org, stable@vger.kernel.org, guoren@kernel.org Cc: huanyi.xj@alibaba-inc.com, guohanjun@huawei.com, zjb194813@alibaba-inc.com, tianhu.hh@alibaba-inc.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220616161746.3565225-1-xianting.tian@linux.alibaba.com> From: Xianting Tian Message-ID: Date: Fri, 17 Jun 2022 00:20:19 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20220616161746.3565225-1-xianting.tian@linux.alibaba.com> Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry, please ignore this one. ÔÚ 2022/6/17 ÉÏÎç12:17, Xianting Tian дµÀ: > Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.") > fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that > can be fixed in a similar way too. > > In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi, > so it would have pfn_base=512 and mem_map began with 512th PFN when > CONFIG_FLATMEM=y. > But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or > less than the pfn_base value. We need page_is_buddy() to verify the buddy to > prevent accessing an invalid buddy. > > Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks") > Cc: stable@vger.kernel.org > Reported-by: zjb194813@alibaba-inc.com > Reported-by: tianhu.hh@alibaba-inc.com > Signed-off-by: Xianting Tian > --- > mm/page_alloc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index a6e682569e5b..1c423faa4b62 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -864,6 +864,9 @@ static inline void __free_one_page(struct page *page, > > buddy_idx = __find_buddy_index(page_idx, order); > buddy = page + (buddy_idx - page_idx); > + > + if (!page_is_buddy(page, buddy, order)) > + goto done_merging; > buddy_mt = get_pageblock_migratetype(buddy); > > if (migratetype != buddy_mt