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

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Message-ID: <e71b7763-4a62-4709-9969-8579bdcff595@lucifer.local>
Date: Mon, 8 Sep 2025 14:12:00 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Jason Gunthorpe <jgg@...dia.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 09:51:01AM -0300, Jason Gunthorpe wrote:
> 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.

Sure can add.

>
> vma_desc_must_be_shared(desc) ?

Maybe _could_be_shared()?

>
> Also 'must not be exec' is common too.

Right, will have a look! :)

>
> Jason