From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933028AbcHXUpI (ORCPT ); Wed, 24 Aug 2016 16:45:08 -0400 Received: from mga07.intel.com ([134.134.136.100]:25425 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932977AbcHXUpH (ORCPT ); Wed, 24 Aug 2016 16:45:07 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,572,1464678000"; d="scan'208";a="870628843" From: Ross Zwisler To: linux-kernel@vger.kernel.org Cc: Ross Zwisler , Andrew Morton , Dan Williams , Dave Chinner , Dave Hansen , Jan Kara , linux-mm@kvack.org, linux-nvdimm@ml01.01.org, Jeff Moyer , stable@vger.kernel.org Subject: [PATCH] mm: silently skip readahead for DAX inodes Date: Wed, 24 Aug 2016 14:37:12 -0600 Message-Id: <20160824203712.4580-1-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.9.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For DAX inodes we need to be careful to never have page cache pages in the 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. Signed-off-by: Ross Zwisler Reported-by: Jeff Moyer Cc: stable@vger.kernel.org --- mm/readahead.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/readahead.c b/mm/readahead.c index 65ec288..a9ba1be 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -8,6 +8,7 @@ */ #include +#include #include #include #include @@ -544,6 +545,9 @@ do_readahead(struct address_space *mapping, struct file *filp, if (!mapping || !mapping->a_ops) return -EINVAL; + if (dax_mapping(mapping)) + return 0; + return force_page_cache_readahead(mapping, filp, index, nr); } -- 2.9.0