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h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=v6VR5slJWMCcwANxphEdf8OCr/x0DfvnAW8+cGd7YvQYL6QlzHHQ+dZmxVcPAOhOd w0IW1eMdj59ZslsO9qhyIUCzIII6iLICD1gDYuRwi2DKpOoebyGbtUO4H9tUKcvKHb dYkUQhgKWSj3O4jfEUOoqvcTR0yAs2gVWaPdER/Q= Date: Thu, 15 Aug 2024 21:53:02 -0700 From: Andrew Morton To: Huang Ying Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, 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: <20240815215302.5ed29b99e94a48aea49269ce@linux-foundation.org> In-Reply-To: <20240816020723.771196-1-ying.huang@intel.com> References: <20240816020723.771196-1-ying.huang@intel.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: bhizufhc67dxt4uoiwatos3u6p6pfjfq X-Rspamd-Queue-Id: C1EDDA001F X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1723783990-708199 X-HE-Meta: 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 ETZ/dlM9 Wm+kP/c/F3hndljXrgJskl0oXVfAEXrEG0hWOoC1TYd6A27Ca4oiWLORtPClehW5I7b0oe8ohBZD4hXVw/6Jp6GLu7/Xt4qHWAeQ72QtD927JMot26zpChOgTnR8IR4NgvRDNSbcege+n0P9za5dAma28ZVWTLZ1kaGf5Vi3q1acAx3/cHRBrZsWPDR60X4lZnxpx2rpUgYHVGOcZ2pwn0RnNbwwHCl0IaBw6ypqzVbmkTON7k/kncrxoAAET9JUvtXHo4l8ahpa3FyZUxSlsILnhYnGDMXZWCgh5yboqupjkOr4= 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: List-Subscribe: List-Unsubscribe: On Fri, 16 Aug 2024 10:07:23 +0800 Huang Ying wrote: > On a system with CXL memory installed, the resource tree (/proc/iomem) > related to CXL memory looks like something as follows. > > 490000000-50fffffff : CXL Window 0 > 490000000-50fffffff : region0 > 490000000-50fffffff : dax0.0 > 490000000-50fffffff : System RAM (kmem) > > When the following command line is run to try writing some memory in > CXL memory range, > > $ dd if=data of=/dev/mem bs=1k seek=19136512 count=1 > dd: error writing '/dev/mem': Bad address > 1+0 records in > 0+0 records out > 0 bytes copied, 0.0283507 s, 0.0 kB/s > > the command fails as expected. 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")?