Re: Linux 5.1-rc5

[Linus Torvalds]

On Wed, Apr 17, 2019 at 1:02 AM Martin Schwidefsky
<schwidefsky@xxxxxxxxxx> wrote:
>
> Grumpf, that does *not* work. For gup the table entries may be read only
> once. Now I remember why I open-coded p4d_offset, pud_offset and pmd_offset
> in arch/s390/mm/gup.c, to avoid to read the table entries twice.
> It will be hard to use the common gup code after all.

Hmm. The common gup code generally should do the "read only once"
thing too (since by definition the gup-fast case is done without
locking), although it's probably the case that most architectures
simply don't care.

What would it require for the generic code to work for s390?

                    Linus