From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) (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 068402CA9; Wed, 4 Dec 2024 03:01:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733281274; cv=none; b=llBIG3Cd2WMsaM284kjMwcuDbHH3sjEt60miXbghGhoOd7qZoNeY06ZMlNQnhY5eCV7f8IMPbiPcbO9a1j0n9exFCVQqM8LbkS95QVfjiZ0gWmWsgfHmhPGmV9fYjLLNZNxje5bcRJ+dxSITPMUKwoqPKd6Nq4+cw9J9nrrlzJc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733281274; c=relaxed/simple; bh=QWOyW0RSuqhTNUZgpIyrrKeMl0sjLC/tNnJLur0kPaY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=X+iX/xzDffWGoC7U90FaX5fzsX083NnOnHVbePxUgMEu7OPl1MDT52BirfgnMFlGjJewvV8Pua5M4WfIYiyCl2nmiDzM71y3HYFkqzmCXpiq7KJrUqrLiW8a4yKmkhtJUJPrYBUnz8UCEh7dC1HAAiK8Et+wDldbwqCZqtRZw4E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Sn9/+nHG; arc=none smtp.client-ip=192.198.163.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Sn9/+nHG" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1733281273; x=1764817273; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=QWOyW0RSuqhTNUZgpIyrrKeMl0sjLC/tNnJLur0kPaY=; b=Sn9/+nHG1Ae42qDOmu5qvfBPduJdccqvnXBu2RC0RUEoS23DYEQ0+oIB Oo5E3bH2/pRCT4H11IgZURYdRV0hnApQa7Y1zouMCgWEVUawFwstHUmAo cMplcXep7HcU7G99/Tl8x2vEEJ0vFnvGojjZBzn/2uYhthN0QJ7HvU3Vs yZ8T1zqKgo/ujFyWWgWLnhcyZuvrxRLdM2ZvZ1ZMGSkXEUgo9/7aEYSSF FnbcBxrvNlggxP+D0HHv4t38lxph970rMWhf6dU84Ei4ggvIsfeAOqeNF 4dkelkJDxeFz4CLLCL580/5nc0tJD8HKsdr1oWGzvrEKkgbTPT7alWlQA A==; X-CSE-ConnectionGUID: DMP5c/hMQaeVRPQW/aMklg== X-CSE-MsgGUID: K7gIEnYITTyNrNPMG7v9Ww== X-IronPort-AV: E=McAfee;i="6700,10204,11275"; a="33451401" X-IronPort-AV: E=Sophos;i="6.12,206,1728975600"; d="scan'208";a="33451401" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Dec 2024 19:01:12 -0800 X-CSE-ConnectionGUID: NwlLOQ4zQyuoS95H/H3L3A== X-CSE-MsgGUID: nKLzkpWsQSe2kjo+Jcmvbg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,206,1728975600"; d="scan'208";a="124459102" Received: from smile.fi.intel.com ([10.237.72.154]) by orviesa002.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Dec 2024 19:01:08 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.98) (envelope-from ) id 1tIfdQ-00000003cpL-1Rrx; Wed, 04 Dec 2024 05:01:04 +0200 Date: Wed, 4 Dec 2024 05:01:04 +0200 From: Andy Shevchenko To: "Huang, Ying" 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 Message-ID: References: <20241202111941.2636613-1-raghavendra.kt@amd.com> <87frn5wac3.fsf@DESKTOP-5N7EMDA> <87iks06w17.fsf@DESKTOP-5N7EMDA> 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=us-ascii Content-Disposition: inline In-Reply-To: <87iks06w17.fsf@DESKTOP-5N7EMDA> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo On Wed, Dec 04, 2024 at 10:07:16AM +0800, Huang, Ying wrote: > 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. I agree on this, please do. > 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. My point was that the regression is obvious and it needs to be fixed. That's all. Revert is a last resort in this sense. -- With Best Regards, Andy Shevchenko