From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941350AbcJSRYq (ORCPT ); Wed, 19 Oct 2016 13:24:46 -0400 Received: from gum.cmpxchg.org ([85.214.110.215]:59970 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935174AbcJSRYp (ORCPT ); Wed, 19 Oct 2016 13:24:45 -0400 From: Johannes Weiner To: Andrew Morton Cc: Linus Torvalds , Jan Kara , Dave Jones , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 0/5] mm: workingset: radix tree subtleties & single-page file refaults Date: Wed, 19 Oct 2016 13:24:23 -0400 Message-Id: <20161019172428.7649-1-hannes@cmpxchg.org> X-Mailer: git-send-email 2.10.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, this is a follow-up to d3798ae8c6f3 ("mm: filemap: don't plant shadow entries without radix tree node"). That patch fixed an issue that was caused mainly by the page cache sneaking special shadow page entries into the radix tree and relying on subtleties in the radix tree code to make that work. The fix also had to stop tracking refaults for single-page files because shadow pages stored as direct pointers in radix_tree_root->rnode weren't properly handled during tree extension. These patches make the radix tree code explicitely support and track such special entries, to eliminate the subtleties and to restore the thrash detection for single-page files. They then turn the BUG_ONs in the shadow shrinker into mere warnings, to prevent unnecessary crashes such as those mentioned in d3798ae8c6f3. The changes have been running stable on my main machines for a couple of days, survived kernel builds, chrome, and various synthetic stress tests that excercise the shadow page tracking code. They've also been solid doing scalability and page cache tests from Mel's mmtests. It's more code, but it should be a lot less fragile. What do you think? include/linux/radix-tree.h | 33 +++++---- include/linux/swap.h | 16 +++-- lib/dma-debug.c | 6 +- lib/radix-tree.c | 142 +++++++++++++++++++++++--------------- mm/filemap.c | 25 ++++--- mm/truncate.c | 2 + mm/workingset.c | 19 +++-- tools/testing/radix-tree/test.c | 4 +- 8 files changed, 149 insertions(+), 98 deletions(-)