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Mon, 20 Jun 2022 12:24:59 +0000 (UTC) X-FDA: 79598533518.31.6143C00 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf13.hostedemail.com (Postfix) with ESMTP id CE884200B8 for ; Mon, 20 Jun 2022 12:24:55 +0000 (UTC) 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 dfw.source.kernel.org (Postfix) with ESMTPS id A4D8561478; Mon, 20 Jun 2022 12:24:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7159FC3411B; Mon, 20 Jun 2022 12:24:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655727894; bh=96SJ91bHPcmvh/H5Q9sbEWTRnmt/EmdCB9umBa+DUFA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TUCemtr7+TrjM61PNrav4LBrQNVpR3vXLmPq6PrARzuYxThcIOIl3uBGpPTtq9IJU Pk4Sy8PDbg+D4Ajk8t3tm2z1odqE27eJNQZoxZK65aBX3xANLHtPUnNomlVPXNba4D VHZ+Aol2uw6LhS2sRDCrnHL52rWbnE94kepIHEwo= Date: Mon, 20 Jun 2022 14:24:51 +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 5.15] mm: validate buddy page before using Message-ID: 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> MIME-Version: 1.0 Content-Type: text/plain; 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dkim=pass header.d=linuxfoundation.org header.s=korg header.b=TUCemtr7; dmarc=pass (policy=none) header.from=linuxfoundation.org; spf=pass (imf13.hostedemail.com: domain of gregkh@linuxfoundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=linuxfoundation.org header.s=korg header.b=TUCemtr7; dmarc=pass (policy=none) header.from=linuxfoundation.org; spf=pass (imf13.hostedemail.com: domain of gregkh@linuxfoundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org X-Rspamd-Server: rspam12 X-Rspam-User: X-Stat-Signature: hjniiy4ukfs7dxhwbsmdsiabwe1zddwe X-Rspamd-Queue-Id: CE884200B8 X-HE-Tag: 1655727895-592973 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: On Mon, Jun 20, 2022 at 08:18:40PM +0800, Xianting Tian wrote: > > 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, So just for 5.18? I am confused. > 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? No, please send fixed up patches for all branches you want them applied to as I do not understand what to do here at all, sorry. greg k-h