From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755269AbbIBOxM (ORCPT ); Wed, 2 Sep 2015 10:53:12 -0400 Received: from mail-yk0-f176.google.com ([209.85.160.176]:33070 "EHLO mail-yk0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754085AbbIBOxK (ORCPT ); Wed, 2 Sep 2015 10:53:10 -0400 Date: Wed, 2 Sep 2015 10:53:07 -0400 From: Tejun Heo To: Josh Boyer Cc: Jeff Moyer , msnitzer@redhat.com, "Richard W.M. Jones" , Li Zefan , Johannes Weiner , cgroups@vger.kernel.org, "Linux-Kernel@Vger. Kernel. Org" Subject: Re: __blkg_lookup oops with 4.2-rcX Message-ID: <20150902145307.GG22326@mtj.duckdns.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Sun, Aug 30, 2015 at 08:30:41AM -0400, Josh Boyer wrote: > Mike and Jeff suggested you be informed of the oops one of our > community members is hitting in Fedora with 4.2-rcX. I thought they > had already sent this upstream to you, but apparently they didn't. > > The latest oops is below. That is with 4.2-rc8. I believe the first > report was against a merge window 4.2 kernel. The full bug report is > here: https://bugzilla.redhat.com/show_bug.cgi?id=1237136 > > I believe Mike and Jeff suspected the cgroup writeback patches. > > josh > > lvm vgchange -a n > /run/lvm/lvmetad.socket: connect failed: No such file or directory > WARNING: Failed to connect to lvmetad. Falling back to internal scanning. > [ 36.157672] BUG: unable to handle kernel NULL pointer dereference > at 0000000000000558 > [ 36.157672] IP: [] __blkg_lookup+0x26/0x70 ... > [ 36.157672] [] blk_throtl_drain+0x5a/0x110 > [ 36.157672] [] blkcg_drain_queue+0x18/0x20 > [ 36.157672] [] __blk_drain_queue+0xc0/0x170 > [ 36.157672] [] blk_queue_bypass_start+0x61/0x80 > [ 36.157672] [] blkcg_deactivate_policy+0x39/0x100 > [ 36.157672] [] blk_throtl_exit+0x38/0x50 > [ 36.157672] [] blkcg_exit_queue+0x3e/0x50 > [ 36.157672] [] blk_release_queue+0x1e/0xc0 > [ 36.157672] [] kobject_release+0x7a/0x190 > [ 36.157672] [] kobject_put+0x2f/0x60 > [ 36.157672] [] blk_cleanup_queue+0x111/0x140 > [ 36.157672] [] cleanup_mapped_device+0xdc/0x100 > [ 36.157672] [] __dm_destroy+0x161/0x260 > [ 36.157672] [] dm_destroy+0x13/0x20 > [ 36.157672] [] dev_remove+0x10d/0x170 > [ 36.157672] [] ctl_ioctl+0x232/0x4d0 > [ 36.157672] [] dm_ctl_ioctl+0x13/0x20 > [ 36.157672] [] do_vfs_ioctl+0x295/0x470 > [ 36.157672] [] SyS_ioctl+0x79/0x90 > [ 36.157672] [] entry_SYSCALL_64_fastpath+0x12/0x71 I think the offending commit is 776687bce42b ("block, blk-mq: draining can't be skipped even if bypass_depth was non-zero"). It looks like the patch makes shutdown path travel data structure which is already destroyed. Will post the fix soon. Thanks. -- tejun