Re: [PATCH v1 2/2] vmalloc: Optimize vfree

[Matthew Wilcox]

On Mon, Jan 05, 2026 at 04:17:38PM +0000, Ryan Roberts wrote:
> +	if (vm->nr_pages) {
> +		start_pfn = page_to_pfn(vm->pages[0]);
> +		nr = 1;
> +		for (i = 1; i < vm->nr_pages; i++) {
> +			unsigned long pfn = page_to_pfn(vm->pages[i]);
> +
> +			if (start_pfn + nr != pfn) {
> +				__free_contig_range(start_pfn, nr);
> +				start_pfn = pfn;
> +				nr = 1;
> +				cond_resched();
> +			} else {
> +				nr++;
> +			}

It kind of feels like __free_contig_range() and this routine do the same
thing -- iterate over each page and make sure that it's compatible with
being freed.  What if we did ...

+	for (i = 0; i < vm->nr_pages; i++) {
+		struct page *page = vm->pages[i];
+
+		if (!put_page_testzero(page)) {
+			__free_frozen_contig_pages(start_page, nr);
+			nr = 0;
+			continue;
+		}
+
+		if (!nr) {
+			start_page = page;
+			nr = 1;
+			continue;
+		}
+
+		if (start_page + nr != page) {
+			__free_frozen_contig_pages(start_page, nr);
+			start_page = page;
+			nr = 1;
+			cond_resched();
+		} else {
+			nr++;
+		}
+	}
+
+	__free_frozen_contig_pages(start_page, nr);

That way we don't need to mess around with returning the number of pages
not freed.