Index: linux-stage/fs/ext4/extents.c
===================================================================
--- linux-stage.orig/fs/ext4/extents.c	2015-07-13 22:22:56.000000000 +0300
+++ linux-stage/fs/ext4/extents.c	2015-07-13 22:24:05.000000000 +0300
@@ -4318,7 +4318,8 @@ static int ext4_find_delayed_extent(stru
 	struct buffer_head *head = NULL;
 	unsigned int nr_pages = PAGE_SIZE / sizeof(struct page *);
 
-	pages = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	/* we are running under i_data_sem so don't reenter the FS code */
+	pages = kmalloc(PAGE_SIZE, GFP_NOFS);
 	if (pages == NULL)
 		return -ENOMEM;