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

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Message-ID: <20250908155652.GE789684@nvidia.com>
Date: Mon, 8 Sep 2025 12:56:52 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: David Hildenbrand <david@...hat.com>
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Subject: Re: [PATCH 03/16] mm: add vma_desc_size(), vma_desc_pages() helpers

On Mon, Sep 08, 2025 at 05:50:18PM +0200, David Hildenbrand wrote:

> So in practice there is indeed not a big difference between a private and
> cow mapping.

Right and most drivers just check SHARED.

But if we are being documentative why they check shared is because the
driver cannot tolerate COW.

I think if someone is cargo culting a diver and sees
'vma_never_cowable' they will have a better understanding of the
driver side issues.

Driver's don't actually care about private vs shared, except this
indirectly implies something about cow.

Jason