linux-kernel - Re: [PATCH v5 3/7] vfio/nvgrace-gpu: Add support for huge pfnmap

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Message-ID: <20251124181521.GV233636@ziepe.ca>
Date: Mon, 24 Nov 2025 14:15:21 -0400
From: Jason Gunthorpe <jgg@...pe.ca>
To: ankita@...dia.com
Cc: yishaih@...dia.com, skolothumtho@...dia.com, kevin.tian@...el.com,
	alex@...zbot.org, aniketa@...dia.com, vsethi@...dia.com,
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	targupta@...dia.com, zhiw@...dia.com, danw@...dia.com,
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Subject: Re: [PATCH v5 3/7] vfio/nvgrace-gpu: Add support for huge pfnmap

On Mon, Nov 24, 2025 at 11:59:22AM +0000, ankita@...dia.com wrote:
> +static size_t nvgrace_gpu_aligned_devmem_size(size_t memlength)
> +{
> +#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
> +	return ALIGN(memlength, PMD_SIZE);
> +#endif
> +#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
> +	return ALIGN(memlength, PUD_SIZE);
> +#endif
> +	return memlength;
> +}

This needs a comment why it is OK to change the size up? Seems really
surprising (and wrong!). The commit message should explain it too.

Jason