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Fri, 16 Aug 2024 05:07:04 +0000 Date: Thu, 15 Aug 2024 22:07:00 -0700 From: Dan Williams To: Andrew Morton , Huang Ying CC: , , , Dan Williams , Davidlohr Bueso , Jonathan Cameron , Dave Jiang , "Alison Schofield" , Vishal Verma , Ira Weiny , Alistair Popple , Andy Shevchenko , Bjorn Helgaas , Baoquan He , Subject: Re: [PATCH] Resource: fix region_intersects() for CXL memory Message-ID: <66bede74cb96f_1c18294ce@dwillia2-mobl3.amr.corp.intel.com.notmuch> References: <20240816020723.771196-1-ying.huang@intel.com> <20240815215302.5ed29b99e94a48aea49269ce@linux-foundation.org> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20240815215302.5ed29b99e94a48aea49269ce@linux-foundation.org> X-ClientProxiedBy: MW4P220CA0030.NAMP220.PROD.OUTLOOK.COM (2603:10b6:303:115::35) To PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH8PR11MB8107:EE_|PH7PR11MB5863:EE_ X-MS-Office365-Filtering-Correlation-Id: 7856b0a5-c083-491c-c940-08dcbdb144b0 X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|366016|1800799024; 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However, the error code is wrong. It > > should be "Operation not permitted" instead of "Bad address". And, > > the following warning is reported in kernel log. > > > > ioremap on RAM at 0x0000000490000000 - 0x0000000490000fff > > WARNING: CPU: 2 PID: 416 at arch/x86/mm/ioremap.c:216 __ioremap_caller.constprop.0+0x131/0x35d > > ... > > > > Presumably we want to fix earlier kernels? If so, are you able to > identify a suitable Fixes: target? Possibly 974854ab0728 ("cxl/acpi: > Track CXL resources in iomem_resource")? At least that commit, but I think this problem potentially goes back farther to: c221c0b0308f device-dax: "Hotplug" persistent memory for use like normal RAM ...because that started the era of "System RAM" as a non-top-level resource. David did a bunch of work to fix this back in: 97f61c8f44ec kernel/resource: make walk_system_ram_res() find all busy IORESOURCE_SYSTEM_RAM resources ..but the fallout in region_intersects() was missed.