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

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Message-ID: <68f8f254b53dc_17217e10069@iweiny-mobl.notmuch>
Date: Wed, 22 Oct 2025 10:03:48 -0500
From: Ira Weiny <ira.weiny@...el.com>
To: Shuai Xue <xueshuai@...ux.alibaba.com>, "Luck, Tony"
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Subject: Re: [PATCH v3 2/3] mm: Change ghes code to allow poison of
 non-struct pfn

Shuai Xue wrote:
> 
> 
> 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.

Can you elaborate on this more?

Ira

>
> 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