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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DC07C43334 for ; Fri, 17 Jun 2022 08:25:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ADEB66B0071; Fri, 17 Jun 2022 04:25:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A68296B0073; Fri, 17 Jun 2022 04:25:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 908136B0074; Fri, 17 Jun 2022 04:25:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 7AB5B6B0071 for ; Fri, 17 Jun 2022 04:25:42 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 5742361561 for ; Fri, 17 Jun 2022 08:25:42 +0000 (UTC) X-FDA: 79587044124.11.D82AA83 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) by imf16.hostedemail.com (Postfix) with ESMTP id F39C818008A for ; Fri, 17 Jun 2022 08:25:40 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R211e4;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_---0VGe5yuS_1655454335; Received: from B-LB6YLVDL-0141.local(mailfrom:xianting.tian@linux.alibaba.com fp:SMTPD_---0VGe5yuS_1655454335) by smtp.aliyun-inc.com; Fri, 17 Jun 2022 16:25:37 +0800 Subject: Re: [PATCH 4.9] mm: page_alloc: 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: <20220616161928.3565294-1-xianting.tian@linux.alibaba.com> From: Xianting Tian Message-ID: Date: Fri, 17 Jun 2022 16:25:35 +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 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655454342; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1mB6YAPrcL+OY1IaLNw4q/9W3YmsOwUYilpp9yiVL1c=; b=l0wJYsCGO86akYaAdcxPKHo/s5lDl61OrVAqrzX79C+KYsCADDpM7CXfEJEiO3k5cs6yUE 0QIvr2+W9IGjPcw36cChgp0YtTg3hEod7vy0Sv8DllA/TuKVhimJE62httnYU5IMcKHWaN OAxrjWZa35nzWN3/6LGk5x0b/Eeqxrc= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655454342; a=rsa-sha256; cv=none; b=jKRHD5BNCxJK/sVh6mW4WRUFuCIlzvuGG9L9er6xN1k0kJwIlPcZWMQHuBgJgMP3wAdwDI +PutDv60HKdDcIWerz2GMTM1ilTOC3PGji7UlN8AvDuNNE8pAIpOJVbTkO9Hfnx2aAuf9H OBHloq3ODFTNRBqheDlSAuMpTUTaga8= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=alibaba.com; spf=pass (imf16.hostedemail.com: domain of xianting.tian@linux.alibaba.com designates 115.124.30.132 as permitted sender) smtp.mailfrom=xianting.tian@linux.alibaba.com Authentication-Results: imf16.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=alibaba.com; spf=pass (imf16.hostedemail.com: domain of xianting.tian@linux.alibaba.com designates 115.124.30.132 as permitted sender) smtp.mailfrom=xianting.tian@linux.alibaba.com X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: F39C818008A X-Stat-Signature: n1n9xtxn81ne67yiiwbwyfaqhi1aaews X-HE-Tag: 1655454340-629406 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 在 2022/6/17 下午4:20, Greg KH 写道: > On Fri, Jun 17, 2022 at 12:19:28AM +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 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 >> -- >> 2.17.1 >> > What is the git commit id of this change in Linus's tree? It is 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 > > thanks, > > greg k-h