1 files changed, 15 insertions, 2 deletions

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index be4bd627caf0..ea36dc355da1 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -861,8 +861,21 @@ 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;