On Mon, 9 May 2022 16:43:30 +0900 Jaewon Kim <jaewon31.kim@xxxxxxxxxxx> wrote:
> The page extension can be prepared for each section. But if the first
> page is not valid, the page extension for the section was not
> initialized though there were many other valid pages within the section.
>
> To support the page extension for all sections, refer to memblock memory
> regions. If the page is valid use the nid from pfn_to_nid, otherwise use
> the previous nid.
>
> Also this pagech changed log to include total sections and a section
> size.
>
> i.e.
> allocated 100663296 bytes of page_ext for 64 sections (1 section : 0x8000000)
Cc Joonsoo, who wrote this code.
Cc Mike, for memblock.
Thanks.
>
> diff --git a/mm/page_ext.c b/mm/page_ext.c
> index 2e66d934d63f..506d58b36a1d 100644
> --- a/mm/page_ext.c
> +++ b/mm/page_ext.c
> @@ -381,41 +381,43 @@ static int __meminit page_ext_callback(struct notifier_block *self,
> void __init page_ext_init(void)
> {
> unsigned long pfn;
> - int nid;
> + int nid = 0;
> + struct memblock_region *rgn;
> + int nr_section = 0;
> + unsigned long next_section_pfn = 0;
>
> if (!invoke_need_callbacks())
> return;
>
> - for_each_node_state(nid, N_MEMORY) {
> + /*
> + * iterate each memblock memory region and do not skip a section having
> + * !pfn_valid(pfn)
> + */
> + for_each_mem_region(rgn) {
> unsigned long start_pfn, end_pfn;
>
> - start_pfn = node_start_pfn(nid);
> - end_pfn = node_end_pfn(nid);
> - /*
> - * start_pfn and end_pfn may not be aligned to SECTION and the
> - * page->flags of out of node pages are not initialized. So we
> - * scan [start_pfn, the biggest section's pfn < end_pfn) here.
> - */
> + start_pfn = (unsigned long)(rgn->base >> PAGE_SHIFT);
> + end_pfn = start_pfn + (unsigned long)(rgn->size >> PAGE_SHIFT);
> +
> + if (start_pfn < next_section_pfn)
> + start_pfn = next_section_pfn;
> +
> for (pfn = start_pfn; pfn < end_pfn;
> pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
>
> - if (!pfn_valid(pfn))
> - continue;
> - /*
> - * Nodes's pfns can be overlapping.
> - * We know some arch can have a nodes layout such as
> - * -------------pfn-------------->
> - * N0 | N1 | N2 | N0 | N1 | N2|....
> - */
> - if (pfn_to_nid(pfn) != nid)
> - continue;
> + if (pfn_valid(pfn))
> + nid = pfn_to_nid(pfn);
> + nr_section++;
> if (init_section_page_ext(pfn, nid))
> goto oom;
> cond_resched();
> }
> + next_section_pfn = pfn;
> }
> +
> hotplug_memory_notifier(page_ext_callback, 0);
> - pr_info("allocated %ld bytes of page_ext\n", total_usage);
> + pr_info("allocated %ld bytes of page_ext for %d sections (1 section : 0x%x)\n",
> + total_usage, nr_section, (1 << SECTION_SIZE_BITS));
> invoke_init_callbacks();
> return;
>
> --
> 2.17.1
>
