From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Goran Subject: Re: INFO: task bcache_writebac:1582 blocked for more than 120 seconds Date: Thu, 12 Jun 2014 02:35:11 +0700 Message-ID: <19010378287.20140612023511@pvgoran.name> References: Reply-To: Pavel Goran Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from pvgoran2.xen.prgmr.com ([71.19.149.48]:35352 "EHLO v2.pvgoran.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750963AbaFKTkr (ORCPT ); Wed, 11 Jun 2014 15:40:47 -0400 In-Reply-To: Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: linux-bcache@vger.kernel.org Hello Nik, Wednesday, June 11, 2014, 9:48:20 PM, you wrote: > I have been running bcache in writeback mode for a while, and had an > unclean shutdown due to a power outage. Machine rebooted, did an > fsck, everything seemed ok, I had a few corrupt files that were open > when the shutdown happened, but no major deal. Then, I started > getting hung tasks: > INFO: task bcache_writebac:1582 blocked for more than 120 seconds. This looks like a well-known bug that manifests itself with the "bcache_writeback locked" messages. It's possible that your cache was corrupted and disabled because of this, and now the bcache_writeback task has no work to do and because of this the "locked" messages appear. (Personally I get these messages when using a bcache device without cache.) Bottom line: these messages probably appear because bcache is *already* disabled. > How can I disable bcache for now? The instructions to install it a > pretty clear, but disabling it isn't. Check whether cache is currently active: cat /sys/block/bcache0/bcache/state If it says "no cache", then there is no active cache on the bcache0 device. If it says "clean", then the cache is there. To disable bcache for the device bcache0 you need to issue the following command: echo "4faa930e-1983-45d3-ac40-e7dd0941d63c" | tee /sys/block/bcache0/bcache/detach Substitute "4faa930e-1983-45d3-ac40-e7dd0941d63c" with the ID of your cache (you can find cache IDs by looking at the /sys/fs/bcache directory). Pavel Goran