Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761530AbcLPWBm (ORCPT ); Fri, 16 Dec 2016 17:01:42 -0500 Received: from mail-wj0-f193.google.com ([209.85.210.193]:34054 "EHLO mail-wj0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754273AbcLPWBa (ORCPT ); Fri, 16 Dec 2016 17:01:30 -0500 Date: Fri, 16 Dec 2016 23:01:21 +0100 From: Michal Hocko To: Brian Foster Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Dave Chinner , "Theodore Ts'o" , Chris Mason , David Sterba , Jan Kara , ceph-devel@vger.kernel.org, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, logfs@logfs.org, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mtd@lists.infradead.org, reiserfs-devel@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, linux-f2fs-devel@lists.sourceforge.net, linux-afs@lists.infradead.org, LKML Subject: Re: [PATCH 2/9 v2] xfs: introduce and use KM_NOLOCKDEP to silence reclaim lockdep false positives Message-ID: <20161216220121.GC7645@dhcp22.suse.cz> References: <20161215140715.12732-1-mhocko@kernel.org> <20161215140715.12732-3-mhocko@kernel.org> <20161216154041.GA7645@dhcp22.suse.cz> <20161216163749.GE8447@bfoster.bfoster> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161216163749.GE8447@bfoster.bfoster> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1457 Lines: 33 On Fri 16-12-16 11:37:50, Brian Foster wrote: > On Fri, Dec 16, 2016 at 04:40:41PM +0100, Michal Hocko wrote: > > Updated patch after Mike noticed a BUG_ON when KM_NOLOCKDEP is used. > > --- > > From 1497e713e11639157aef21cae29052cb3dc7ab44 Mon Sep 17 00:00:00 2001 > > From: Michal Hocko > > Date: Thu, 15 Dec 2016 13:06:43 +0100 > > Subject: [PATCH] xfs: introduce and use KM_NOLOCKDEP to silence reclaim > > lockdep false positives > > > > Now that the page allocator offers __GFP_NOLOCKDEP let's introduce > > KM_NOLOCKDEP alias for the xfs allocation APIs. While we are at it > > also change KM_NOFS users introduced by b17cb364dbbb ("xfs: fix missing > > KM_NOFS tags to keep lockdep happy") and use the new flag for them > > instead. There is really no reason to make these allocations contexts > > weaker just because of the lockdep which even might not be enabled > > in most cases. > > > > Hi Michal, > > I haven't gone back to fully grok b17cb364dbbb ("xfs: fix missing > KM_NOFS tags to keep lockdep happy"), so I'm not really familiar with > the original problem. FWIW, there was another KM_NOFS instance added by > that commit in xlog_cil_prepare_log_vecs() that is now in > xlog_cil_alloc_shadow_bufs(). Perhaps Dave can confirm whether the > original issue still applies..? Yes, I've noticed that but the reworked code looked sufficiently different that I didn't dare to simply convert it. -- Michal Hocko SUSE Labs