static void smaps_account(struct mem_size_stats *mss, struct page *page,
		bool compound, bool young, bool dirty, bool locked,
		bool present)
{
	struct folio *folio = page_folio(page);
	int i, nr = compound ? compound_nr(page) : 1;
	unsigned long size = nr * PAGE_SIZE;

	/*
	 * First accumulate quantities that depend only on |size| and the type
	 * of the compound page.
	 */
	if (folio_test_anon(folio)) {
		mss->anonymous += size;
		if (!folio_test_swapbacked(folio) && !dirty &&
		    !folio_test_dirty(folio))
			mss->lazyfree += size;
	}

	if (folio_test_ksm(folio))
		mss->ksm += size;

	mss->resident += size;
	/* Accumulate the size in pages that have been accessed. */
	if (young || folio_test_young(folio) || folio_test_referenced(folio))
		mss->referenced += size;

	/*
	 * Then accumulate quantities that may depend on sharing, or that may
	 * differ page-by-page.
	 *
	 * refcount == 1 for present entries guarantees that the folio is mapped
	 * exactly once. For large folios this implies that exactly one
	 * PTE/PMD/... maps (a part of) this folio.
	 *
	 * Treat all non-present entries (where relying on the mapcount and
	 * refcount doesn't make sense) as "maybe shared, but not sure how
	 * often". We treat device private entries as being fake-present.
	 *
	 * Note that it would not be safe to read the mapcount especially for
	 * pages referenced by migration entries, even with the PTL held.
	 */
	if (folio_ref_count(folio) == 1 || !present) {
		smaps_page_accumulate(mss, folio, size, size << PSS_SHIFT,
				      dirty, locked, present);
		return;
	}

Warm-up