linux-kernel - Re: [PATCH v3 2/3] mm: Change ghes code to allow poison of non-struct pfn

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Message-ID: <81b1f1c6-4308-41bb-9f65-f158d30f27bd@linux.alibaba.com>
Date: Wed, 22 Oct 2025 14:53:09 +0800
From: Shuai Xue <xueshuai@...ux.alibaba.com>
To: "Luck, Tony" <tony.luck@...el.com>, "Weiny, Ira" <ira.weiny@...el.com>,
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Subject: Re: [PATCH v3 2/3] mm: Change ghes code to allow poison of non-struct
 pfn



在 2025/10/22 01:19, Luck, Tony 写道:
>>>      pfn = PHYS_PFN(physical_addr);
>>> -   if (!pfn_valid(pfn) && !arch_is_platform_page(physical_addr)) {
>>
>> Tony,
>>
>> I'm not an SGX expert but does this break SGX by removing
>> arch_is_platform_page()?
>>
>> See:
>>
>> 40e0e7843e23 ("x86/sgx: Add infrastructure to identify SGX EPC pages")
>> Cc: Tony Luck <tony.luck@...el.com>
>>
> Ira,
> 
> I think this deletion makes the GHES code always call memory_failure()
> instead of bailing out here on "bad" page frame numbers.
> 
> That centralizes the checks for different types of memory into
> memory_failure().
> 
> -Tony

Hi, Tony, Ankit and Ira,

Finally, we're seeing other use cases that need to handle errors for
non-struct page PFNs :)

IMHO, non-struct page PFNs are common in production environments.
Besides NVIDIA Grace GPU device memory, we also use reserved DRAM memory
managed by a separate VMEM allocator. This VMEM allocator is designed
for virtual machine memory allocation, significantly reducing kernel
memory management overhead by minimizing page table maintenance.

To enable hardware error isolation for these memory pages, we've already
removed this sanity check internally. This change makes memory_failure()
the central point for handling all memory types, which is a much cleaner
architecture.

Reviewed-by: Shuai Xue <xueshuai@...ux.alibaba.com>

Thanks.
Shuai