From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946026AbWGOLRf (ORCPT ); Sat, 15 Jul 2006 07:17:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932510AbWGOLRf (ORCPT ); Sat, 15 Jul 2006 07:17:35 -0400 Received: from pne-smtpout1-sn1.fre.skanova.net ([81.228.11.98]:24480 "EHLO pne-smtpout1-sn1.fre.skanova.net") by vger.kernel.org with ESMTP id S932506AbWGOLRe (ORCPT ); Sat, 15 Jul 2006 07:17:34 -0400 To: linux-kernel@vger.kernel.org Cc: Arjan van de Ven , dm-devel@redhat.com Subject: lockdep warning when nesting dm devices From: Peter Osterlund Date: 15 Jul 2006 13:17:29 +0200 Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org If I run this as root: # dd if=/dev/zero of=tmpfile bs=1M count=10 # /sbin/losetup -f ./tmpfile # echo "0 10000 linear /dev/loop0 0" | /sbin/dmsetup create test # echo "0 10000 linear /dev/mapper/test 0" | /sbin/dmsetup create test2 I get the following warning from the lockdep validator. Btw, is there a limit on how many dm devices can be chained? I guess there will be a kernel stack overflow if you try to chain together too many devices. ============================================= [ INFO: possible recursive locking detected ] --------------------------------------------- vol_id/2468 is trying to acquire lock: (&md->io_lock){----}, at: [] dm_request+0x23/0x158 [dm_mod] but task is already holding lock: (&md->io_lock){----}, at: [] dm_request+0x23/0x158 [dm_mod] other info that might help us debug this: 1 lock held by vol_id/2468: #0: (&md->io_lock){----}, at: [] dm_request+0x23/0x158 [dm_mod] stack backtrace: [] show_trace_log_lvl+0x133/0x14d [] show_trace+0x1b/0x1d [] dump_stack+0x26/0x28 [] __lock_acquire+0x8aa/0xd29 [] lock_acquire+0x68/0x83 [] down_read+0x50/0x60 [] dm_request+0x23/0x158 [dm_mod] [] generic_make_request+0x94/0x322 [] __map_bio+0x75/0x130 [dm_mod] [] __split_bio+0x382/0x3c1 [dm_mod] [] dm_request+0xdd/0x158 [dm_mod] [] generic_make_request+0x94/0x322 [] submit_bio+0x6f/0x112 [] submit_bh+0xce/0x11f [] block_read_full_page+0x26c/0x2e2 [] blkdev_readpage+0x19/0x1b [] __do_page_cache_readahead+0x1bf/0x28a [] blockable_page_cache_readahead+0x5d/0xc4 [] page_cache_readahead+0x176/0x1bc [] do_generic_mapping_read+0x49d/0x50d [] __generic_file_aio_read+0xfd/0x22c [] generic_file_read+0x9e/0xbe [] vfs_read+0x98/0x115 [] sys_read+0x47/0x6e [] sysenter_past_esp+0x56/0x8d [] 0xb7f79410 -- Peter Osterlund - petero2@telia.com http://web.telia.com/~u89404340