Re: [PATCH] mm/gup: fix gup_fast with dynamic page table folding

[Linus Torvalds]

On Fri, Sep 11, 2020 at 12:04 PM Vasily Gorbik <gor@xxxxxxxxxxxxx> wrote:
>
> Currently to make sure that every page table entry is read just once
> gup_fast walks perform READ_ONCE and pass pXd value down to the next
> gup_pXd_range function by value e.g.:
[ ... ]

Ack, this looks sane to me.

I was going to ask how horrible it would be to convert all the other
users, but a quick grep convinced me that yeah, it's only GUP that is
this special, and we don't want to make this interface be the real one
for everything else too..

                Linus