Messages in this thread | | | Date | Fri, 17 Jun 2022 11:54:21 +0200 | From | Oscar Salvador <> | Subject | Re: [PATCH v2 2/2] mm: memory_hotplug: introduce SECTION_CANNOT_OPTIMIZE_VMEMMAP |
| |
On Fri, Jun 17, 2022 at 09:43:33AM +0200, David Hildenbrand wrote: > VmemmapSelfHosted, then the function names get nicer.
Definitely.
> > > +#endif > > + > > /* > > * On an anonymous page mapped into a user virtual memory area, > > * page->mapping points to its anon_vma, not to a struct address_space; > > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > > index 1089ea8a9c98..e2de7ed27e9e 100644 > > --- a/mm/hugetlb_vmemmap.c > > +++ b/mm/hugetlb_vmemmap.c > > @@ -101,6 +101,14 @@ void hugetlb_vmemmap_free(struct hstate *h, struct page *head) > > { > > unsigned long vmemmap_addr = (unsigned long)head; > > unsigned long vmemmap_end, vmemmap_reuse, vmemmap_pages; > > + struct mem_section *ms = __pfn_to_section(page_to_pfn(head)); > > + struct page *memmap; > > + > > + memmap = sparse_decode_mem_map(ms->section_mem_map, > > + pfn_to_section_nr(page_to_pfn(head))); > > Why can't we check the head page directly? Either I need more coffee or > this can be simplified.
Uhm, maybe I'm the one who needs coffe here but we have something like:
[ hot-plugges section ] [memmap pages][normal pages]
we only mark as VmemmapSelfHosted the memmap pages.
head page points to [normal pages] range, that is why we need to go and get its mem_map to see whether those pages are marked.
Does it make sense? Or am I missing something?
> > + > > + if (PageVmemmap_self_hosted(memmap)) > > Maybe that's the right place for a comment, an ascii art, and how it is > safe to only check the first vmemmap page due to alignment restrictions.
Yes, definitely worth putting in a comment.
> > + /* > > + * Let us flag self-hosted memmap > > + */ > > I think that comment can be dropped because the code does exactly that.
Yeah, was mainly to picture it, but it needs to go as it is worthless.
-- Oscar Salvador SUSE Labs
| |