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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35A63C001E0 for ; Tue, 15 Aug 2023 18:55:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239502AbjHOSyo (ORCPT ); Tue, 15 Aug 2023 14:54:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239536AbjHOSyU (ORCPT ); Tue, 15 Aug 2023 14:54:20 -0400 Received: from mx.treblig.org (unknown [IPv6:2a00:1098:5b::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD49C2123; Tue, 15 Aug 2023 11:53:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=treblig.org ; s=bytemarkmx; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID :Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID :Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To: Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe :List-Post:List-Owner:List-Archive; bh=//toRj/PKXJjaN9Lb1xLslhcEFyKob0fP3zRV2NepOY=; b=mCWSJQ3+0FPdTBBgkanltHH+rS rX61emmsNMIugv+6Tk4t48w3LC91RVFaSll2gmoJs0D7Hw25uL6zETFZQ/EzE4M4Iqotd6iVbK0dj ISvu1aPpkqNBzPnBilvnU1ofAUfLY7+pJeg4r8fyS69t6EdyoG9zMqyCbtGZYmaam8XtCxQMNZIYK wQGsTgw9y5pYdQd1L9XuvkqpTLhW8mf5K905JwJScL4prcbhGOaQ3GVNxgp73kHK75In9ag/LeAZi xUu89BGEG3Mv1T6Xrb6W6v2j7NACUQXHy6BJlpz+tdicBAERNe+Z0v70wLzZI5A6uIE/GLKq/UN3l 7Jy0OXCA==; Received: from dg by mx.treblig.org with local (Exim 4.94.2) (envelope-from ) id 1qVz9Q-0076hZ-EE; Tue, 15 Aug 2023 18:52:20 +0000 Date: Tue, 15 Aug 2023 18:52:20 +0000 From: "Dr. David Alan Gilbert" To: Carlos Carvalho Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: 6.5.0rc5 fs hang - ext4? raid? Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: X-Chocolate: 70 percent or better cocoa solids preferably X-Operating-System: Linux/5.10.0-23-amd64 (x86_64) X-Uptime: 18:49:52 up 40 days, 4:21, 1 user, load average: 0.02, 0.03, 0.00 User-Agent: Mutt/2.0.5 (2021-01-21) Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org * Carlos Carvalho (carlos@fisica.ufpr.br) wrote: > Dr. David Alan Gilbert (dave@treblig.org) wrote on Mon, Aug 14, 2023 at 06:02:53PM -03: > > I'm seeing a few hangs on a fs after upgrading to fedora 39's bleeding > > edge; which is running kernel 6.5.0-0.rc5.20230808git14f9643dc90a.37.fc39.x86_64 > > It was always solid prior to that. It seems to trigger on heavy IO > > on this fs. > > Good news! No, I didn't forget the smiley... Maybe now the problem has become > sufficiently bad to be visible/solvable... > > 6.4.* also doesn't run in one of our machines, which has heavy I/O load. The > first symptom is that rsync downloads hang and abort with timeout. 1 or 2 > days later the amount of modified pages waiting to go to disk reaches several > GB, as reported by /proc/meminfo, but disks remain idle. Finally reading from > the arrays collapses. I'm not sure this is a related fault - I mean it might be, but my failure is much more deterministic; it seems solid on 6.4.x to me, but just fails reliably somewhere in 6.5. Dave > This is just the worst case. Since early 5.* I/O performance has dropped > absurdly. In all our disk servers this is easy to see: just generate lots of > writes quickly (for example expanding a kernel tarball). Using top I see that > kworker starts using 100% cpu but disks stay idle (as seen by dstat or sar). If > you do a sync or umount it takes looooong to reach ~0 modified pages for the > sync or umount to return. > > In the server I mentioned above where 6.4.* don't stand the load, which is one > of the largest free software mirrors of the world, even sometimes 6.1 > collapses: I/O becomes so slow that service (apache) stops. > > The problem gets progressively worse with time after booting. It's hardly > noticeable in the first hour after boot, and easily seen after ~3-4 days of > uptime. The higher the (write) I/O load the faster it appears. > > All this is with ext4 and raid6 with >~ 14 disks in the arrays. > > I don't have debug info because these are production machines and I only > compile in the kernel the bare minimum essential for operation. It's always > pure kernel.org releases; gcc versions vary, for 6.4* it's gcc-13, for 6.1* > gcc-12 is used, on Debian unstable updated more than 4 times/week. -- -----Open up your eyes, open up your mind, open up your code ------- / Dr. David Alan Gilbert | Running GNU/Linux | Happy \ \ dave @ treblig.org | | In Hex / \ _________________________|_____ http://www.treblig.org |_______/