From: "Huang, Ying" <ying.huang@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-cxl@vger.kernel.org,
Dan Williams <dan.j.williams@intel.com>,
David Hildenbrand <david@redhat.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 -v3 1/3] resource: Fix region_intersects() vs add_memory_driver_managed()
Date: Mon, 09 Sep 2024 08:57:40 +0800 [thread overview]
Message-ID: <87le011w57.fsf@yhuang6-desk2.ccr.corp.intel.com> (raw)
In-Reply-To: <20240907202458.dfe90bfee071021706af91eb@linux-foundation.org> (Andrew Morton's message of "Sat, 7 Sep 2024 20:24:58 -0700")
Andrew Morton <akpm@linux-foundation.org> writes:
> On Fri, 6 Sep 2024 11:07:11 +0800 Huang Ying <ying.huang@intel.com> wrote:
>
>> On a system with CXL memory, the resource tree (/proc/iomem) related
>> to CXL memory may look like something as follows.
>>
>> 490000000-50fffffff : CXL Window 0
>> 490000000-50fffffff : region0
>> 490000000-50fffffff : dax0.0
>> 490000000-50fffffff : System RAM (kmem)
>>
>> Because drivers/dax/kmem.c calls add_memory_driver_managed() during
>> onlining CXL memory, which makes "System RAM (kmem)" a descendant of
>> "CXL Window X". This confuses region_intersects(), which expects all
>> "System RAM" resources to be at the top level of iomem_resource. This
>> can lead to bugs.
>>
>> ...
>>
>> Fixes: c221c0b0308f ("device-dax: "Hotplug" persistent memory for use like normal RAM")
>
> Do you believe this should be fixed in earlier (-stable) kernels?
Yes. I think that we should fix this in -stable kernels. Although no
severe bug will be triggered on x86 in the earlier kernels, it may be a
real bug for some other architectures.
--
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2024-09-09 1:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-06 3:07 [PATCH -v3 0/3] " Huang Ying
2024-09-06 3:07 ` [PATCH -v3 1/3] " Huang Ying
2024-09-08 3:24 ` Andrew Morton
2024-09-09 0:57 ` Huang, Ying [this message]
2024-09-06 3:07 ` [PATCH -v3 2/3] resource: Make alloc_free_mem_region() works for iomem_resource Huang Ying
2024-09-09 7:04 ` David Hildenbrand
2024-09-09 7:07 ` Huang, Ying
2024-09-09 8:04 ` David Hildenbrand
2024-09-06 3:07 ` [PATCH -v3 3/3] resource, kunit: Add test case for region_intersects() Huang Ying
2024-09-29 19:45 ` Kees Bakker
2024-09-30 0:53 ` Huang, Ying
2024-09-30 17:36 ` Kees Bakker
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