Re: Futexes & Folios

Thomas Gleixner
2023-05-13T19:57:02Z

On Sat, May 13 2023 at 17:16, Matthew Wilcox wrote:

> Here's a patch which converts the futex code from using pages to using
> folios. I do have some questions.
>
> - I assume we really do want to base the key on the page offset of the
> futex in the file. That is, it's not good enough to base the key
> on the folio's index because the folio can be split after setting up
> the key, and if it is we'd then fail to find the futex later.

Correct.

> - In hugetlbfs, it doesn't matter whether the pgoff is based on base
> pages or huge page size -- as long as it's consistent between
> invocations, everything will work

Yes.

The patch looks sane, but I need to have a look with brain more awake

Thanks,

tglx