diff options
| -rw-r--r-- | mm/migrate.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index be3f141e53a4..2803a6698dd6 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -168,19 +168,19 @@ retry: /* * Remove references for a page and establish the new page with the correct * basic settings to be able to stop accesses to the page. + * + * The number of remaining references must be: + * 1 for anonymous pages without a mapping + * 2 for pages with a mapping + * 3 for pages with a mapping and PagePrivate set. */ static int migrate_page_remove_references(struct page *newpage, - struct page *page, int nr_refs) + struct page *page) { struct address_space *mapping = page_mapping(page); struct page **radix_pointer; - /* - * Avoid doing any of the following work if the page count - * indicates that the page is in use or truncate has removed - * the page. - */ - if (!mapping || page_mapcount(page) + nr_refs != page_count(page)) + if (!mapping) return -EAGAIN; /* @@ -218,7 +218,8 @@ static int migrate_page_remove_references(struct page *newpage, &mapping->page_tree, page_index(page)); - if (!page_mapping(page) || page_count(page) != nr_refs || + if (!page_mapping(page) || + page_count(page) != 2 + !!PagePrivate(page) || *radix_pointer != page) { write_unlock_irq(&mapping->tree_lock); return -EAGAIN; @@ -309,7 +310,7 @@ int migrate_page(struct page *newpage, struct page *page) BUG_ON(PageWriteback(page)); /* Writeback must be complete */ - rc = migrate_page_remove_references(newpage, page, 2); + rc = migrate_page_remove_references(newpage, page); if (rc) return rc; @@ -348,7 +349,7 @@ int buffer_migrate_page(struct page *newpage, struct page *page) head = page_buffers(page); - rc = migrate_page_remove_references(newpage, page, 3); + rc = migrate_page_remove_references(newpage, page); if (rc) return rc; |