From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-119.freemail.mail.aliyun.com (out30-119.freemail.mail.aliyun.com [115.124.30.119]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7FF35802; Wed, 4 Dec 2024 02:07:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.119 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733278070; cv=none; b=PPPv2nLrHpCE6T+sq/rVntVmpJtLS2E03+7k74B25o1xuV4eLnRx3IdfAQ/SB7CjrUCvfML/YXFnz/CCK1F1ZltoMwmnVyshu4qYnavdbtuR2oA4dVo0AgvvSoAg862G/ziS7V2RW2RHneHZcs6cEzKG0riEj7L3Ks5uUdoPxHk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733278070; c=relaxed/simple; bh=j9/8en4k0z7ZOt5Ac3cEuqOl1rpE26CkdKKvFLbjyi8=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=BPegKnDpbyqstgDybzDxGbXatLvt64i0/Cdh2VWR5qHprh3tqaNdVr3h/zSQ2Ai3fcDgxPdA+/Pjg9Sg9jGFoLjEA7/bs1KqIM4Q2h+Yy9nzX+eFFchG/ioy+pzcbsRL1SGgjG7o849IbWB2ZlrTeFb7AxyDTHc3Wr/UoAcJq7A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=RLg14YH6; arc=none smtp.client-ip=115.124.30.119 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="RLg14YH6" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1733278065; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; bh=20il1jHvB1Q1OdtdS8d6Zxhc05oWCgHhA7oH7Iu+aJA=; b=RLg14YH6dfzD9ticF5XyZljwRKNhfPN5/XX0/lKGivdW/ew3VUOswhzVknj9a567AzUP+os4RbJ+qp5D1J0z1r4wvg2WT0ewqafiow+0U0kcec33jrvLwnGLPazGQsQTiWa4S5lBYWRDbgtR9dbfQtppkwNyjp0IYRJWWXbFmOc= Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0WKoEPSt_1733278037 cluster:ay36) by smtp.aliyun-inc.com; Wed, 04 Dec 2024 10:07:43 +0800 From: "Huang, Ying" To: Andy Shevchenko Cc: Raghavendra K T , linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, bharata@amd.com, Andrew Morton , Dan Williams , David Hildenbrand , Davidlohr Bueso , Jonathan Cameron , Dave Jiang , Alison Schofield , Vishal Verma , Ira Weiny , Alistair Popple , Bjorn Helgaas , Baoquan He , ilpo.jarvinen@linux.intel.com, Mika Westerberg , Fontenot Nathan , Wei Huang Subject: Re: [RFC PATCH] resource: Fix CXL node not populated issue In-Reply-To: (Andy Shevchenko's message of "Tue, 3 Dec 2024 15:41:28 +0200") References: <20241202111941.2636613-1-raghavendra.kt@amd.com> <87frn5wac3.fsf@DESKTOP-5N7EMDA> Date: Wed, 04 Dec 2024 10:07:16 +0800 Message-ID: <87iks06w17.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Hi, Andy, Andy Shevchenko writes: > On Tue, Dec 03, 2024 at 02:26:52PM +0800, Huang, Ying wrote: >> Raghavendra K T writes: > > ... > >> > git bisect had led to below commit >> > Fixes: b4afe4183ec7 ("resource: fix region_intersects() vs add_memory_driver_managed()") >> >> This breaks you case, sorry about that. But this also fixed a real bug >> too. So, it's not appropriate just to revert it blindly. > > Linus was clear about this recently. Even if it fixes a bug, regression is > still regression and might (*) lead to a revert. > https://lwn.net/Articles/990599/ > > (*) in general fixes are better than reverts, but depends on the timing in > the release cycle the revert may be the only option. I don't think that the timing is so tight that we should not work on proper fix firstly. I'm trying to work with the reporter on this. BTW, the commit b4afe4183ec7 ("resource: fix region_intersects() vs add_memory_driver_managed()") fixed a security related bug. The bug weakened the protection to prevent users read/write system memory via /dev/mem. So, IMO, we need to be more careful about this. --- Best Regards, Huang, Ying