From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753552Ab0JARSK (ORCPT ); Fri, 1 Oct 2010 13:18:10 -0400 Received: from relay3.sgi.com ([192.48.152.1]:43862 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753188Ab0JARSI (ORCPT ); Fri, 1 Oct 2010 13:18:08 -0400 Subject: Re: [patch] xfs: properly account for reclaimed inodes From: Alex Elder Reply-To: aelder@sgi.com To: Johannes Weiner Cc: xfs@oss.sgi.com, John Hawley , linux-kernel@vger.kernel.org, stable@kernel.org In-Reply-To: <20101001074354.GF2618@cmpxchg.org> References: <20101001074354.GF2618@cmpxchg.org> Content-Type: text/plain; charset="UTF-8" Date: Fri, 01 Oct 2010 12:17:23 -0500 Message-ID: <1285953443.2422.4.camel@doink> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 01 Oct 2010 17:17:24.0195 (UTC) FILETIME=[83A22B30:01CB618C] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2010-10-01 at 09:43 +0200, Johannes Weiner wrote: > When marking an inode reclaimable, a per-AG counter is increased, the > inode is tagged reclaimable in its per-AG tree, and, when this is the > first reclaimable inode in the AG, the AG entry in the per-mount tree > is also tagged. > > When an inode is finally reclaimed, however, it is only deleted from > the per-AG tree. Neither the counter is decreased, nor is the parent > tree's AG entry untagged properly. > > Since the tags in the per-mount tree are not cleared, the inode > shrinker iterates over all AGs that have had reclaimable inodes at one > point in time. > > The counters on the other hand signal an increasing amount of slab > objects to reclaim. Since "70e60ce xfs: convert inode shrinker to > per-filesystem context" this is not a real issue anymore because the > shrinker bails out after one iteration. > > But the problem was observable on a machine running v2.6.34, where the > reclaimable work increased and each process going into direct reclaim > eventually got stuck on the xfs inode shrinking path, trying to scan > several million objects. > > Fix this by properly unwinding the reclaimable-state tracking of an > inode when it is reclaimed. > > Signed-off-by: Johannes Weiner > Cc: stable@kernel.org Yes, this looks right to me. The state was correctly adjusted in xfs_iget_cache_hit() when a RECLAIMABLE inode is found in the cache, but it was not done when reclaim completes. Reviewed-by: Alex Elder