On Wed, 24 Aug 2016 14:37:12 -0600 Ross Zwisler <ross.zwisler(a)linux.intel.com>
For DAX inodes we need to be careful to never have page cache pages
mapping->page_tree. This radix tree should be composed only of DAX
exceptional entries and zero pages.
ltp's readahead02 test was triggering a warning because we were trying to
insert a DAX exceptional entry but found that a page cache page had already
been inserted into the tree. This page was being inserted into the radix
tree in response to a readahead(2) call.
Readahead doesn't make sense for DAX inodes, but we don't want it to report
a failure either. Instead, we just return success and don't do any work.
@@ -8,6 +8,7 @@
@@ -544,6 +545,9 @@ do_readahead(struct address_space *mapping, struct file *filp,
if (!mapping || !mapping->a_ops)
+ if (dax_mapping(mapping))
+ return 0;
Please don't force readers to go spend minutes putzing around in the
git tree trying to understand your code.
/* these things considered useful! */