From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751687Ab3FZIWZ (ORCPT ); Wed, 26 Jun 2013 04:22:25 -0400 Received: from cantor2.suse.de ([195.135.220.15]:33231 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751271Ab3FZIWW (ORCPT ); Wed, 26 Jun 2013 04:22:22 -0400 Date: Wed, 26 Jun 2013 10:22:20 +0200 From: Michal Hocko To: Glauber Costa Cc: Andrew Morton , Dave Chinner , linux-mm@kvack.org, LKML Subject: Re: linux-next: slab shrinkers: BUG at mm/list_lru.c:92 Message-ID: <20130626082220.GG28748@dhcp22.suse.cz> References: <20130617151403.GA25172@localhost.localdomain> <20130617143508.7417f1ac9ecd15d8b2877f76@linux-foundation.org> <20130617223004.GB2538@localhost.localdomain> <20130618062623.GA20528@localhost.localdomain> <20130619071346.GA9545@dhcp22.suse.cz> <20130619142801.GA21483@dhcp22.suse.cz> <20130620141136.GA3351@localhost.localdomain> <20130620151201.GD27196@dhcp22.suse.cz> <20130621090021.GB12424@dhcp22.suse.cz> <20130623115127.GA7986@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130623115127.GA7986@localhost.localdomain> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun 23-06-13 15:51:29, Glauber Costa wrote: > On Fri, Jun 21, 2013 at 11:00:21AM +0200, Michal Hocko wrote: > > On Thu 20-06-13 17:12:01, Michal Hocko wrote: > > > I am bisecting it again. It is quite tedious, though, because good case > > > is hard to be sure about. > > > > OK, so now I converged to 2d4fc052 (inode: convert inode lru list to generic lru > > list code.) in my tree and I have double checked it matches what is in > > the linux-next. This doesn't help much to pin point the issue I am > > afraid :/ > > > Can you revert this patch (easiest way ATM is to rewind your tree to a point > right before it) and apply the following patch? OK, I am testing it now. > As Dave has mentioned, it is very likely that this bug was already there, we > were just not ever checking imbalances. The attached patch would tell us at > least if the imbalance was there before. Maybe I wasn't clear before but I have seen mostly hangs (posted earlier) during bisection. I do not remember BUG_ONs on imbalances after inode_lru_isolate fix. > If this is the case, I would suggest > turning the BUG condition into a WARN_ON_ONCE since we would be officially > not introducing any regression. It is no less of a bug, though, and we should > keep looking for it. > > The main change from before / after the patch is that we are now keeping things > per node. One possibility of having this BUGing would be to have an inode to be > inserted into one node-lru and removed from another. I cannot see how it could > happen, because kernel pages are stable in memory and are not moved from node > to node. We could still have some sort of weird bug in the node calculation > function. > In any case, would it be possible for you to artificially restrict > your setup to a single node ? Although I have no idea how to do that, we seem > to have no parameter to disable numa. Maybe booting with less memory, enough to > fit a single node? I can play with memmap to use areas on from a single node. Let's see whether the patch in the follow up email shows something first. -- Michal Hocko SUSE Labs