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 E48A5C43334 for ; Mon, 20 Jun 2022 12:19:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242242AbiFTMTB (ORCPT ); Mon, 20 Jun 2022 08:19:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242752AbiFTMSq (ORCPT ); Mon, 20 Jun 2022 08:18:46 -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 DBD8B273F; Mon, 20 Jun 2022 05:18:44 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R651e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045170;MF=xianting.tian@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0VGxWMOb_1655727520; Received: from B-LB6YLVDL-0141.local(mailfrom:xianting.tian@linux.alibaba.com fp:SMTPD_---0VGxWMOb_1655727520) by smtp.aliyun-inc.com; Mon, 20 Jun 2022 20:18:41 +0800 Subject: Re: [PATCH 5.15] mm: validate buddy page before using To: Greg KH Cc: akpm@linux-foundation.org, ziy@nvidia.com, stable@vger.kernel.org, guoren@kernel.org, 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> <20220616161746.3565225-6-xianting.tian@linux.alibaba.com> <35bd7396-f5aa-e154-9495-0a36fc6f6a33@linux.alibaba.com> <8b16a502-5ad5-1efb-0d84-ed0a8ae63c0e@linux.alibaba.com> From: Xianting Tian Message-ID: Date: Mon, 20 Jun 2022 20:18:40 +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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/6/20 下午8:06, Greg KH 写道: > On Mon, Jun 20, 2022 at 07:57:05PM +0800, Xianting Tian wrote: >> 在 2022/6/20 下午7:42, Greg KH 写道: >>> On Mon, Jun 20, 2022 at 06:54:44PM +0800, Xianting Tian wrote: >>>> 在 2022/6/20 下午6:17, Greg KH 写道: >>>>> On Fri, Jun 17, 2022 at 12:17:45AM +0800, Xianting Tian wrote: >>>>>> 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 unset_migratetype_isolate(), we also need the fix, so move page_is_buddy() >>>>>> from mm/page_alloc.c to mm/internal.h >>>>>> >>>>>> 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/internal.h | 34 ++++++++++++++++++++++++++++++++++ >>>>>> mm/page_alloc.c | 37 +++---------------------------------- >>>>>> mm/page_isolation.c | 3 ++- >>>>>> 3 files changed, 39 insertions(+), 35 deletions(-) >>>>> What is the commit id of this in Linus's tree? >>>> It is also this one， >>>> >>>> commit 787af64d05cd528aac9ad16752d11bb1c6061bb9 >>>> Author: Zi Yan >>>> Date:   Wed Mar 30 15:45:43 2022 -0700 >>>> >>>>     mm: page_alloc: validate buddy before check its migratetype. >>>> >>>>     Whenever a buddy page is found, page_is_buddy() should be called to >>>>     check its validity.  Add the missing check during pageblock merge check. >>>> >>>>     Fixes: 1dd214b8f21c ("mm: page_alloc: avoid merging non-fallbackable >>>> pageblocks with others") >>>>     Link: >>>> https://lore.kernel.org/all/20220330154208.71aca532@gandalf.local.home/ >>>>     Reported-and-tested-by: Steven Rostedt >>>>     Signed-off-by: Zi Yan >>>>     Signed-off-by: Linus Torvalds >>> This commit looks nothing like what you posted here. >>> >>> Why the vast difference with no explaination as to why these are so >>> different from the other backports you provided here? Also why is the >>> subject lines changed? >> Yes, the changes of 5.15 are not same with others branches, because we need >> additional fix for 5.15, >> >> You can check it in the thread: >> >> https://lore.kernel.org/linux-mm/435B45C3-E6A5-43B2-A5A2-318C748691FC@nvidia.com/ >> >> Right. But pfn_valid_within() was removed since 5.15. So your fix is >> required for kernels between 5.15 and 5.17 (inclusive). > What is "your fix" here? > > This change differs a lot from what is in Linus's tree now, so this all > needs to be resend and fixed up as I mention above if we are going to be > able to take this. As-is, it's all not correct so are dropped. I think, for branches except 5.15,  you can just backport Zi Yan's commit 787af64d05cd in Linus tree. I won't send more patches further, For 5.15, because it need additional fix except commit 787af64d05cd,  I will send a new patch as your comments. Is it ok for you? > > thanks, > > greg k-h