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 5156AC433EF for ; Thu, 16 Jun 2022 16:20:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E09EA6B0098; Thu, 16 Jun 2022 12:20:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D92446B0099; Thu, 16 Jun 2022 12:20:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C35846B009A; Thu, 16 Jun 2022 12:20:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id B04416B0098 for ; Thu, 16 Jun 2022 12:20:25 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 89BFA33F6F for ; Thu, 16 Jun 2022 16:20:25 +0000 (UTC) X-FDA: 79584611610.18.369974C Received: from out30-42.freemail.mail.aliyun.com (out30-42.freemail.mail.aliyun.com [115.124.30.42]) by imf15.hostedemail.com (Postfix) with ESMTP id 4DF29A0087 for ; Thu, 16 Jun 2022 16:20:23 +0000 (UTC) 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 ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655396425; a=rsa-sha256; cv=none; b=IxzD/eNk35AtB8QwNT4TepM0kDvDEOeBnsekf2Q5+wE9CtdfLoDTl1mefpx/tfjvVdKXGs CzydPWwFlV5lQ9yIvuXiCFr4EemDcHAEYx4nQAtc2kIAiDDbLSlwHzwz/u4KC/o3xYZ64A 4fnPJ3sco7NTWnYcTQ9luI/1B/LY0k4= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=none; spf=pass (imf15.hostedemail.com: domain of xianting.tian@linux.alibaba.com designates 115.124.30.42 as permitted sender) smtp.mailfrom=xianting.tian@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655396425; 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=P6UjAKdaH8Pxv5Jplcw9FH/1v4P88x7iDJRlhPrHov4=; b=bvGLJcbWsRTNtKgxhOMZlPSa2El5knePgjuv04CdVkjPcti7cRl0uur1pmqjmmAosikx05 xMhqe5OwFprm2j9frZvQATW/EMTfN6r+NTmTQFZ5CCka2fQUMPgpCx8Hyt/pwaBjHbrlur Nw7nIZyBHk539LTaI7gpmZ239RZ8JZk= X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 4DF29A0087 X-Stat-Signature: weno579i143ntfads5exmafb8pwj4og5 Authentication-Results: imf15.hostedemail.com; dkim=none; spf=pass (imf15.hostedemail.com: domain of xianting.tian@linux.alibaba.com designates 115.124.30.42 as permitted sender) smtp.mailfrom=xianting.tian@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com X-Rspam-User: X-HE-Tag: 1655396423-306736 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: 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