From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B4ACC34022 for ; Wed, 19 Feb 2020 03:45:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F27D20801 for ; Wed, 19 Feb 2020 03:45:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726647AbgBSDpa (ORCPT ); Tue, 18 Feb 2020 22:45:30 -0500 Received: from mail104.syd.optusnet.com.au ([211.29.132.246]:34918 "EHLO mail104.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726439AbgBSDp3 (ORCPT ); Tue, 18 Feb 2020 22:45:29 -0500 Received: from dread.disaster.area (pa49-179-138-28.pa.nsw.optusnet.com.au [49.179.138.28]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id 086907EB642; Wed, 19 Feb 2020 14:45:27 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1j4GIf-0005ZF-UR; Wed, 19 Feb 2020 14:45:25 +1100 Date: Wed, 19 Feb 2020 14:45:25 +1100 From: Dave Chinner To: Matthew Wilcox Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, ocfs2-devel@oss.oracle.com, linux-xfs@vger.kernel.org Subject: Re: [PATCH v6 00/19] Change readahead API Message-ID: <20200219034525.GH10776@dread.disaster.area> References: <20200217184613.19668-1-willy@infradead.org> <20200218045633.GH10776@dread.disaster.area> <20200218134230.GN7778@bombadil.infradead.org> <20200218212652.GR10776@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200218212652.GR10776@dread.disaster.area> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=X6os11be c=1 sm=1 tr=0 a=zAxSp4fFY/GQY8/esVNjqw==:117 a=zAxSp4fFY/GQY8/esVNjqw==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=IkcTkHD0fZMA:10 a=l697ptgUJYAA:10 a=7-415B0cAAAA:8 a=TZYe3LLFzD7hkv9TfyEA:9 a=QEXdDO2ut3YA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 19, 2020 at 08:26:52AM +1100, Dave Chinner wrote: > On Tue, Feb 18, 2020 at 05:42:30AM -0800, Matthew Wilcox wrote: > > On Tue, Feb 18, 2020 at 03:56:33PM +1100, Dave Chinner wrote: > > > Latest version in your git tree: > > > > > > $ ▶ glo -n 5 willy/readahead > > > 4be497096c04 mm: Use memalloc_nofs_save in readahead path > > > ff63497fcb98 iomap: Convert from readpages to readahead > > > 26aee60e89b5 iomap: Restructure iomap_readpages_actor > > > 8115bcca7312 fuse: Convert from readpages to readahead > > > 3db3d10d9ea1 f2fs: Convert from readpages to readahead > > > $ > > > > > > merged into a 5.6-rc2 tree fails at boot on my test vm: > > > > > > [ 2.423116] ------------[ cut here ]------------ > > > [ 2.424957] list_add double add: new=ffffea000efff4c8, prev=ffff8883bfffee60, next=ffffea000efff4c8. > > > [ 2.428259] WARNING: CPU: 4 PID: 1 at lib/list_debug.c:29 __list_add_valid+0x67/0x70 > > > [ 2.457484] Call Trace: > > > [ 2.458171] __pagevec_lru_add_fn+0x15f/0x2c0 > > > [ 2.459376] pagevec_lru_move_fn+0x87/0xd0 > > > [ 2.460500] ? pagevec_move_tail_fn+0x2d0/0x2d0 > > > [ 2.461712] lru_add_drain_cpu+0x8d/0x160 > > > [ 2.462787] lru_add_drain+0x18/0x20 > > > > Are you sure that was 4be497096c04 ? I ask because there was a > > Yes, because it's the only version I've actually merged into my > working tree, compiled and tried to run. :P > > > version pushed to that git tree that did contain a list double-add > > (due to a mismerge when shuffling patches). I noticed it and fixed > > it, and 4be497096c04 doesn't have that problem. I also test with > > CONFIG_DEBUG_LIST turned on, but this problem you hit is going to be > > probabilistic because it'll depend on the timing between whatever other > > list is being used and the page actually being added to the LRU. > > I'll see if I can reproduce it. Just updated to a current TOT Linus kernel and your latest branch, and so far this is 100% reproducable. Not sure how I'm going to debug it yet, because it's init that is triggering it.... Cheers, Dave. -- Dave Chinner david@fromorbit.com