From: Andrew Morton <akpm@linux-foundation.org>
To: Huang Ying <ying.huang@intel.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-cxl@vger.kernel.org,
Dan Williams <dan.j.williams@intel.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
Dave Jiang <dave.jiang@intel.com>,
Alison Schofield <alison.schofield@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Ira Weiny <ira.weiny@intel.com>,
Alistair Popple <apopple@nvidia.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Bjorn Helgaas <bhelgaas@google.com>, Baoquan He <bhe@redhat.com>
Subject: Re: [PATCH] Resource: fix region_intersects() for CXL memory
Date: Thu, 15 Aug 2024 21:53:02 -0700 [thread overview]
Message-ID: <20240815215302.5ed29b99e94a48aea49269ce@linux-foundation.org> (raw)
In-Reply-To: <20240816020723.771196-1-ying.huang@intel.com>
On Fri, 16 Aug 2024 10:07:23 +0800 Huang Ying <ying.huang@intel.com> 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")?
next prev parent reply other threads:[~2024-08-16 4:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-16 2:07 Huang Ying
2024-08-16 4:53 ` Andrew Morton [this message]
2024-08-16 5:07 ` Dan Williams
2024-08-16 8:57 ` David Hildenbrand
2024-08-16 5:01 ` Dan Williams
2024-08-16 7:43 ` Huang, Ying
2024-08-22 1:29 ` Dan Williams
2024-09-02 2:07 ` Huang, Ying
2024-09-02 11:56 ` Andy Shevchenko
2024-09-03 0:43 ` Huang, Ying
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