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 3993FC43334 for ; Mon, 20 Jun 2022 10:17:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239255AbiFTKRl (ORCPT ); Mon, 20 Jun 2022 06:17:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236511AbiFTKRk (ORCPT ); Mon, 20 Jun 2022 06:17:40 -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 037C613F69; Mon, 20 Jun 2022 03:17:36 -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 B0267B8100E; Mon, 20 Jun 2022 10:17:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11AA8C341CD; Mon, 20 Jun 2022 10:17:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655720253; bh=aImB4dOAnpq7fh83qe9WnFO2jaS12cjvFvZjTv0nroc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=yUmvhvmRw3/ZAXcKitI1BMSv+r0TqfV64BDHoZ/kO2QT6n/DT8xZEM4mGmEJUtvNc shEMA3hJfdKjQjcCJLgtOql20A/gsWbYHvgceKs7RLzMa9ynzcCSgaZgWCSW6lIr28 rOyYSlAl46rLAomRQs+PqiiIP0dBK7a5UOUo85Dg= Date: Mon, 20 Jun 2022 12:17:22 +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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, Jun 17, 2022 at 04:25:35PM +0800, Xianting Tian wrote: > > 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 > All now queued up, thanks. greg k-h