diff options
| -rw-r--r-- | mm/rmap.c | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 7df7984d476c..2ee1ef0f317b 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -56,6 +56,7 @@ #include <linux/mmu_notifier.h> #include <linux/migrate.h> #include <linux/hugetlb.h> +#include <linux/backing-dev.h> #include <asm/tlbflush.h> @@ -926,11 +927,8 @@ int page_mkclean(struct page *page) if (page_mapped(page)) { struct address_space *mapping = page_mapping(page); - if (mapping) { + if (mapping) ret = page_mkclean_file(mapping, page); - if (page_test_and_clear_dirty(page_to_pfn(page), 1)) - ret = 1; - } } return ret; @@ -1116,6 +1114,7 @@ void page_add_file_rmap(struct page *page) */ void page_remove_rmap(struct page *page) { + struct address_space *mapping = page_mapping(page); bool anon = PageAnon(page); bool locked; unsigned long flags; @@ -1138,8 +1137,19 @@ void page_remove_rmap(struct page *page) * 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; 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 ((!anon || PageSwapCache(page)) && + if (mapping && !mapping_cap_account_dirty(mapping) && page_test_and_clear_dirty(page_to_pfn(page), 1)) set_page_dirty(page); /* |