From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754538AbeBGPwp (ORCPT ); Wed, 7 Feb 2018 10:52:45 -0500 Received: from mga01.intel.com ([192.55.52.88]:59346 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754377AbeBGPwn (ORCPT ); Wed, 7 Feb 2018 10:52:43 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,473,1511856000"; d="scan'208";a="199409973" Date: Wed, 7 Feb 2018 07:52:29 -0800 From: Andi Kleen To: syzbot Cc: akpm@linux-foundation.org, aryabinin@virtuozzo.com, jack@suse.cz, jlayton@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mgorman@techsingularity.net, mingo@kernel.org, rgoldwyn@suse.com, syzkaller-bugs@googlegroups.com, linux-fsdevel@vger.kernel.org Subject: Re: INFO: task hung in sync_blockdev Message-ID: <20180207155229.GC10945@tassilo.jf.intel.com> References: <001a11447070ac6fcb0564a08cb1@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <001a11447070ac6fcb0564a08cb1@google.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > #0: (&bdev->bd_mutex){+.+.}, at: [<0000000040269370>] > __blkdev_put+0xbc/0x7f0 fs/block_dev.c:1757 > 1 lock held by blkid/19199: > #0: (&bdev->bd_mutex){+.+.}, at: [<00000000b4dcaa18>] > __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 > #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000033edf9f2>] > n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 > 1 lock held by syz-executor5/19330: > #0: (&bdev->bd_mutex){+.+.}, at: [<00000000b4dcaa18>] > __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 > 1 lock held by syz-executor5/19331: > #0: (&bdev->bd_mutex){+.+.}, at: [<00000000b4dcaa18>] > __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 It seems multiple processes deadlocked on the bd_mutex. Unfortunately there's no backtrace for the lock acquisitions, so it's hard to see the exact sequence. It seems lockdep is already active, so it's likely not just an ordering violation, but something else. -Andi