From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753639Ab0HYUMN (ORCPT ); Wed, 25 Aug 2010 16:12:13 -0400 Received: from cantor2.suse.de ([195.135.220.15]:49714 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753578Ab0HYUML (ORCPT ); Wed, 25 Aug 2010 16:12:11 -0400 Date: Wed, 25 Aug 2010 22:11:26 +0200 From: Jan Kara To: Dave Chinner Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, jack@suse.cz, npiggin@kernel.dk Subject: Re: [PATCH 0/2] radix-tree: fix writeback livelock avoidance code Message-ID: <20100825201126.GF2738@quack.suse.cz> References: <1282281727-15088-1-git-send-email-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1282281727-15088-1-git-send-email-david@fromorbit.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 20-08-10 15:22:05, Dave Chinner wrote: > The following two patches fix bugs in the new radix tree functionality used to > implement the writeback livelock avoidance code. Both bugs manifest themselves > as stray PAGECACHE_TAG_TOWRITE tags in the mapping->page_tree radix tree > resulting in livelocks during tag lookups. More subtly, they also appear to > result in writeback tree walks occasionally terminating early and so not > actually writing all the pages they are supposed to. > > Please review and test - these are pretty serious problems for the writeback code. OK, I've updated Andrew's radix tree test suite to use the latest incarnation of radix-tree.c and added check to verify consistency of tags in a radix tree. Without your patches, the new error check triggers almost immediately for radix_tree_range_tag_if_tagged, with them the test passes. Honza -- Jan Kara SUSE Labs, CR