From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cloud1-vm154.de-nserver.de ([178.250.10.56]:20576 "EHLO cloud1-vm154.de-nserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753070AbcI0GlK (ORCPT ); Tue, 27 Sep 2016 02:41:10 -0400 Subject: Re: deadlock with btrfs heavy i/o and kswapd To: Chris Mason , "linux-btrfs@vger.kernel.org" References: <281582c9-1307-612e-77e6-9d768337ea3e@profihost.ag> <8116272d-6c30-431a-c3e1-781b17bea2c6@fb.com> From: Stefan Priebe - Profihost AG Message-ID: <0cd5ff1d-f3ef-ccfb-4460-884470dab199@profihost.ag> Date: Tue, 27 Sep 2016 08:41:06 +0200 MIME-Version: 1.0 In-Reply-To: <8116272d-6c30-431a-c3e1-781b17bea2c6@fb.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi Chris, today i had this again. But i can't see any stack traces. I just see. INFO: kworker/u128:5:24301 blocked for more than 120 seconds. ... INFO: kworker/u128:5:24301 blocked for more than 120 seconds. ... INFO: task mysqld:929 blocked for more ... ... sysrq w just prints: sysrq: SysRq: Show Blcoked State but nothing more. Stefan Am 22.09.2016 um 16:28 schrieb Chris Mason: > > > On 09/22/2016 02:41 AM, Stefan Priebe - Profihost AG wrote: >> Hi, >> >> i always encounter btrfs deadlocks / hung tasks, when i have a lot of >> cached mem and i'm doing heavy rsync --inplace operations in my system >> from btrfs zlib compressed disk A to btrfs zlib compressed disk B. >> >> The last output i see in this case is kswapd0 running for a long time at >> 100% cpu. Then the whole system get's stuck. I cannot connect to ssh >> anymore but the kernel still prints hung tasks every few minutes. >> >> May be relevant the system has NO swap. >> >> vm.vfs_cache_pressure = 100 >> vm.swappiness = 50 > > Are you able to capture the stack dumps? A sysrq-w would really help. > > -chris >