diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 2b4fe3f109046e4a845a206f1c66fff72cf2621b..d51bd7283243924bbae8784fc6e1d67a8f431924 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -817,8 +817,21 @@ EXPORT_SYMBOL(_copy_from_iter_full_nocache); static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) { - struct page *head = compound_head(page); - size_t v = n + offset + page_address(page) - page_address(head); + struct page *head; + size_t v = n + offset; + + /* + * The general case needs to access the page order in order + * to compute the page size. + * However, we mostly deal with order-0 pages and thus can + * avoid a possible cache line miss for requests that fit all + * page orders. + */ + if (n <= v && v <= PAGE_SIZE) + return true; + + head = compound_head(page); + v += (page - head) << PAGE_SHIFT; if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head)))) return true;