Re: [PATCH v1 09/11] x86/mm/pat: remove MEMTYPE_*_MATCH

Lorenzo Stoakes
2025-05-06T09:31:16Z

On Mon, May 05, 2025 at 02:10:53PM +0200, David Hildenbrand wrote:
> On 28.04.25 22:23, Lorenzo Stoakes wrote:
> > On Fri, Apr 25, 2025 at 10:17:13AM +0200, David Hildenbrand wrote:
> > > The "memramp() shrinking" scenario no longer applies, so let's remove
> > > that now-unnecessary handling.
> >
> > I wonder if we could remove even more of the code here given the
> > simplifications here? But not a big deal.
>
> It might make sense to inline memtype_match().
>
> diff --git a/arch/x86/mm/pat/memtype_interval.c b/arch/x86/mm/pat/memtype_interval.c
> index 9d03f0dbc4715..e5844ed1311ed 100644
> --- a/arch/x86/mm/pat/memtype_interval.c
> +++ b/arch/x86/mm/pat/memtype_interval.c
> @@ -49,21 +49,6 @@ INTERVAL_TREE_DEFINE(struct memtype, rb, u64, subtree_max_end,
> static struct rb_root_cached memtype_rbroot = RB_ROOT_CACHED;
> -static struct memtype *memtype_match(u64 start, u64 end)
> -{
> - struct memtype *entry_match;
> -
> - entry_match = interval_iter_first(&memtype_rbroot, start, end-1);
> -
> - while (entry_match != NULL && entry_match->start < end) {
> - if (entry_match->start == start && entry_match->end == end)
> - return entry_match;
> - entry_match = interval_iter_next(entry_match, start, end-1);
> - }
> -
> - return NULL; /* Returns NULL if there is no match */
> -}
> -
> static int memtype_check_conflict(u64 start, u64 end,
> enum page_cache_mode reqtype,
> enum page_cache_mode *newtype)
> @@ -119,14 +104,16 @@ int memtype_check_insert(struct memtype *entry_new, enum page_cache_mode *ret_ty
> struct memtype *memtype_erase(u64 start, u64 end)
> {
> - struct memtype *entry_old;
> -
> - entry_old = memtype_match(start, end);
> - if (!entry_old)
> - return ERR_PTR(-EINVAL);
> -
> - interval_remove(entry_old, &memtype_rbroot);
> - return entry_old;
> + struct memtype *entry = interval_iter_first(&memtype_rbroot, start, end - 1);
> +
> + while (entry && entry->start < end) {
> + if (entry->start == start && entry->end == end) {
> + interval_remove(entry, &memtype_rbroot);
> + return entry;
> + }
> + entry = interval_iter_next(entry, start, end - 1);
> + }
> + return ERR_PTR(-EINVAL);
> }
> struct memtype *memtype_lookup(u64 addr)
>
>
> Thanks for all the review!

You're welcome :)

I _think_ I'm all caught up on my side of this review, ping me if there's
anything more you need from me.

>
> --
> Cheers,
>
> David / dhildenb
>

Cheers, Lorenzo