linux-kernel - Re: [PATCH 03/16] mm: add vma_desc_size(), vma_desc

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Message-ID: <20250908125101.GX616306@nvidia.com>
Date: Mon, 8 Sep 2025 09:51:01 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
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Subject: Re: [PATCH 03/16] mm: add vma_desc_size(), vma_desc_pages() helpers

On Mon, Sep 08, 2025 at 12:10:34PM +0100, Lorenzo Stoakes wrote:
>  static int secretmem_mmap_prepare(struct vm_area_desc *desc)
>  {
> -	const unsigned long len = desc->end - desc->start;
> +	const unsigned long len = vma_desc_size(desc);
>  
>  	if ((desc->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
>  		return -EINVAL;

I wonder if we should have some helper for this shared check too, it
is a bit tricky with the two flags. Forced-shared checks are pretty
common.

vma_desc_must_be_shared(desc) ?

Also 'must not be exec' is common too.

Jason