From: Peter Osterlund <petero2@telia.com>
To: linux-kernel@vger.kernel.org
Cc: Arjan van de Ven <arjan@linux.intel.com>, dm-devel@redhat.com
Subject: lockdep warning when nesting dm devices
Date: 15 Jul 2006 13:17:29 +0200 [thread overview]
Message-ID: <m34pxj6rsm.fsf@telia.com> (raw)
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: [<e08475b6>] dm_request+0x23/0x158 [dm_mod]
but task is already holding lock:
(&md->io_lock){----}, at: [<e08475b6>] 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: [<e08475b6>] dm_request+0x23/0x158 [dm_mod]
stack backtrace:
[<c01041bc>] show_trace_log_lvl+0x133/0x14d
[<c01048e4>] show_trace+0x1b/0x1d
[<c01049b2>] dump_stack+0x26/0x28
[<c0134b92>] __lock_acquire+0x8aa/0xd29
[<c013535e>] lock_acquire+0x68/0x83
[<c01314ff>] down_read+0x50/0x60
[<e08475b6>] dm_request+0x23/0x158 [dm_mod]
[<c01e02e8>] generic_make_request+0x94/0x322
[<e084649a>] __map_bio+0x75/0x130 [dm_mod]
[<e08472e0>] __split_bio+0x382/0x3c1 [dm_mod]
[<e0847670>] dm_request+0xdd/0x158 [dm_mod]
[<c01e02e8>] generic_make_request+0x94/0x322
[<c01e2a3b>] submit_bio+0x6f/0x112
[<c01647a1>] submit_bh+0xce/0x11f
[<c0167902>] block_read_full_page+0x26c/0x2e2
[<c016a74a>] blkdev_readpage+0x19/0x1b
[<c014c5ba>] __do_page_cache_readahead+0x1bf/0x28a
[<c014c6e2>] blockable_page_cache_readahead+0x5d/0xc4
[<c014c961>] page_cache_readahead+0x176/0x1bc
[<c01466c7>] do_generic_mapping_read+0x49d/0x50d
[<c0147084>] __generic_file_aio_read+0xfd/0x22c
[<c0148491>] generic_file_read+0x9e/0xbe
[<c0163460>] vfs_read+0x98/0x115
[<c0163869>] sys_read+0x47/0x6e
[<c0103069>] sysenter_past_esp+0x56/0x8d
[<b7f79410>] 0xb7f79410
--
Peter Osterlund - petero2@telia.com
http://web.telia.com/~u89404340
next reply other threads:[~2006-07-15 11:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-15 11:17 Peter Osterlund [this message]
2006-07-17 2:45 ` lockdep warning when nesting dm devices Alasdair G Kergon
2006-07-17 2:45 ` Alasdair G Kergon
2006-07-17 9:16 ` Arjan van de Ven
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=m34pxj6rsm.fsf@telia.com \
--to=petero2@telia.com \
--cc=arjan@linux.intel.com \
--cc=dm-devel@redhat.com \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.