Re: [PATCH V2 2/2] mm/highmem: Lift memcpy_[to|from]_page to core

[Dan Williams]

On Tue, Dec 8, 2020 at 2:49 PM Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote:
[..]
> > So what's your preferred poison?
> >
> > 1. Corrupt random data in whatever's been mapped into the next page (which
> >    is what the helpers currently do)
>
> Please no.

My assertion is that the kernel can't know it's corruption, it can
only know that the driver is abusing the API. So over-copy and WARN
seems better than violently regress by crashing what might have been
working silently before.