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 360DBC43334 for ; Fri, 17 Jun 2022 08:21:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380840AbiFQIVA (ORCPT ); Fri, 17 Jun 2022 04:21:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380841AbiFQIVA (ORCPT ); Fri, 17 Jun 2022 04:21:00 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 21DF46832E; Fri, 17 Jun 2022 01:20:58 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id CF3A1B827C9; Fri, 17 Jun 2022 08:20:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E96E9C3411B; Fri, 17 Jun 2022 08:20:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655454055; bh=tufoqh4ehHqakBbaLoDipUirQp4IZJN5clq1fuvPmrg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MxArUWDtv/6SHdyajkZUlcecLvHfawxc2aGXkrMk2ojL4VJl/WE3ELNkZ+pCuUWk3 m3TbPbXtikJ4mg6KrRo/SFDn+Vd7iEE1BLGOA6eJtUawLsWjREC/qfHl8mNdBul/dG KhMfSTqY32UGHyX6TnpfzQ3CmFElrRO9am36bORs= Date: Fri, 17 Jun 2022 10:20:52 +0200 From: Greg KH To: Xianting Tian 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 Subject: Re: [PATCH 4.9] mm: page_alloc: validate buddy page before using Message-ID: References: <20220616161928.3565294-1-xianting.tian@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220616161928.3565294-1-xianting.tian@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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? thanks, greg k-h