diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 4472036..2adb899 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1022,17 +1022,15 @@
 EXPORT_SYMBOL(test_set_page_writeback);
 
 /*
- * Return true if any of the pages in the mapping are marged with the
+ * Return true if any of the pages in the mapping are marked with the
  * passed tag.
  */
 int mapping_tagged(struct address_space *mapping, int tag)
 {
-	unsigned long flags;
 	int ret;
-
-	read_lock_irqsave(&mapping->tree_lock, flags);
+	rcu_read_lock();
 	ret = radix_tree_tagged(&mapping->page_tree, tag);
-	read_unlock_irqrestore(&mapping->tree_lock, flags);
+	rcu_read_unlock();
 	return ret;
 }
 EXPORT_SYMBOL(mapping_tagged);
diff --git a/mm/readahead.c b/mm/readahead.c
index fc52f9f..c5c8981 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -149,20 +149,19 @@
 	/*
 	 * Preallocate as many pages as we will need.
 	 */
-	read_lock_irq(&mapping->tree_lock);
 	for (page_idx = 0; page_idx < nr_to_read; page_idx++) {
 		pgoff_t page_offset = offset + page_idx;
 
 		if (page_offset > end_index)
 			break;
 
+		rcu_read_lock();
 		page = radix_tree_lookup(&mapping->page_tree, page_offset);
+		rcu_read_unlock();
 		if (page)
 			continue;
 
-		read_unlock_irq(&mapping->tree_lock);
 		page = page_cache_alloc_cold(mapping);
-		read_lock_irq(&mapping->tree_lock);
 		if (!page)
 			break;
 		page->index = page_offset;
@@ -171,7 +170,6 @@
 			SetPageReadahead(page);
 		ret++;
 	}
-	read_unlock_irq(&mapping->tree_lock);
 
 	/*
 	 * Now start the IO.  We ignore I/O errors - if the page is not