- /*
- * Now that the last pte has gone, s390 must transfer dirty
- * flag from storage key to struct page. We can usually skip
- * this if the page is anon, so about to be freed; but perhaps
- * not if it's in swapcache - there might be another pte slot
- * containing the swap entry, but page not yet written to swap.
- *
- * And we can skip it on file pages, so long as the filesystem
- * participates in dirty tracking (note that this is not only an
- * optimization but also solves problems caused by dirty flag in
- * storage key getting set by a write from inside kernel); but need to
- * catch shm and tmpfs and ramfs pages which have been modified since
- * creation by read fault.
- *
- * Note that mapping must be decided above, before decrementing
- * mapcount (which luckily provides a barrier): once page is unmapped,
- * it could be truncated and page->mapping reset to NULL at any moment.
- * Note also that we are relying on page_mapping(page) to set mapping
- * to &swapper_space when PageSwapCache(page).
- */
- if (mapping && !mapping_cap_account_dirty(mapping) &&
- page_test_and_clear_dirty(page_to_pfn(page), 1))
- set_page_dirty(page);