> > Then, we'd only need a config option to allow for that to happen.
>
> Something incomplete and very hacky just to give an idea. It would try allocating
> it if there is actual code running that would need it, and then have it
> stick around forever.
>
Thanks a lot for this David :) I think this is a much better idea and
reduces the amount code and reuse the existing infrastructure.
I will try this approach in the next version.
<snip>
> + /*
> + * Our raised reference will prevent the shrinker from ever having
> + * success -> static.
> + */
> + if (atomic_read(&huge_zero_folio_is_static))
> + return huge_zero_folio;
> + /* TODO: memblock allocation if buddy is not up yet? Or Reject that earlier. */
Do we need memblock allocation? At least the use cases I forsee for
static pmd zero page are all after the mm is up. So I don't see why we
need to allocate it via memblock.
> + if (!get_huge_zero_page())
> + return NULL;
> + if (atomic_cmpxchg(&huge_zero_folio_is_static, 0, 1) != 0)
> + put_huge_zero_page();
> + return huge_zero_folio;
> +
> +}
> +#endif /* CONFIG_STATIC_HUGE_ZERO_FOLIO */
> +
> static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
> struct shrink_control *sc)
> {
>
--
Pankaj
