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

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Date: Fri, 24 Oct 2025 11:26:19 +0000
From: Ankit Agrawal <ankita@...dia.com>
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Subject: Re: [PATCH v3 2/3] mm: Change ghes code to allow poison of non-struct
 pfn

>>> 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?
>
> We reserve a significant portion of DRAM memory at boot time using
> kernel command line parameters. This reserved memory is then managed by
>
> our internal VMEM allocator, which handles memory allocation and
> deallocation for virtual machines.
>
>To minimize memory overhead, we intentionally avoid creating struct
> pages for this reserved memory region.

Thanks Shuai for the explanation and providing the "Reviewed-by". We use
the PFNMAP for the similar reason to save on the memory usage by the
struct pages.

Also as mentioned in the 1/3 patch, I'll move this patch to the top.