Re: [v2.6.26-rc1] possible circular locking in ecryptfs

From: Ingo Molnar
Date: Sun May 18 2008 - 07:41:14 EST



* Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote:

> [Ingo Molnar - Fri, May 09, 2008 at 11:44:23AM +0200]
> |
> | * Ingo Molnar <mingo@xxxxxxx> wrote:
> |
> | > x86.git testing found the following "possible circular locking"
> | > lockdep warning, generated by the ecryptfs code:
> |
> | the correct URL for the config is:
> |
> | http://redhat.com/~mingo/misc/config-Wed_May__7_16_17_31_CEST_2008.bad
> |
> | this is reproducible, it happened a second time since i originally
> | reported it.
> |
> | Ingo
>
> Hi Ingo, I've just sent patch, could you test it, please?
>
> http://lkml.org/lkml/2008/5/10/20

that patch is now upstream - but see below there's still a circular
dependency.

Ingo

[ 21.530026]
[ 21.530026] =======================================================
[ 21.530026] [ INFO: possible circular locking dependency detected ]
[ 21.530026] 2.6.26-rc2-sched-devel.git #1205
[ 21.530026] -------------------------------------------------------
[ 21.530026] multipath.stati/1379 is trying to acquire lock:
[ 21.530026] (&ecryptfs_daemon_hash_mux){--..}, at: [<c020cca2>] ecryptfs_miscdev_open+0x22/0x140
[ 21.530026]
[ 21.530026] but task is already holding lock:
[ 21.530026] (misc_mtx){--..}, at: [<c02f4b92>] misc_open+0x22/0x120
[ 21.530026]
[ 21.530026] which lock already depends on the new lock.
[ 21.530026]
[ 21.530026]
[ 21.530026] the existing dependency chain (in reverse order) is:
[ 21.530026]
[ 21.530026] -> #1 (misc_mtx){--..}:
[ 21.530026] [<c01438aa>] __lock_acquire+0xc3a/0x1100
[ 21.530026] [<c0143de6>] lock_acquire+0x76/0xa0
[ 21.530026] [<c05d032a>] mutex_lock_nested+0x7a/0x280
[ 21.530026] [<c02f4cb5>] misc_register+0x25/0x140
[ 21.530026] [<c020cb5c>] ecryptfs_init_ecryptfs_miscdev+0x2c/0x60
[ 21.530026] [<c020c5fe>] ecryptfs_init_messaging+0x1ee/0x280
[ 21.530026] [<c0837662>] ecryptfs_init+0xc2/0x1b0
[ 21.530026] [<c0824852>] kernel_init+0x132/0x250
[ 21.530026] [<c010365f>] kernel_thread_helper+0x7/0x10
[ 21.530026] [<ffffffff>] 0xffffffff
[ 21.530026]
[ 21.530026] -> #0 (&ecryptfs_daemon_hash_mux){--..}:
[ 21.530026] [<c01436cd>] __lock_acquire+0xa5d/0x1100
[ 21.530026] [<c0143de6>] lock_acquire+0x76/0xa0
[ 21.530026] [<c05d032a>] mutex_lock_nested+0x7a/0x280
[ 21.530026] [<c020cca2>] ecryptfs_miscdev_open+0x22/0x140
[ 21.530026] [<c02f4bf2>] misc_open+0x82/0x120
[ 21.530026] [<c0187c26>] chrdev_open+0x86/0x150
[ 21.530026] [<c0183289>] __dentry_open+0xa9/0x260
[ 21.530026] [<c0183487>] nameidata_to_filp+0x47/0x60
[ 21.530026] [<c018fda4>] do_filp_open+0x184/0x7a0
[ 21.530026] [<c01830aa>] do_sys_open+0x4a/0xb0
[ 21.530026] [<c018317e>] sys_open+0x2e/0x40
[ 21.530026] [<c010330e>] syscall_call+0x7/0xb
[ 21.530026] [<ffffffff>] 0xffffffff
[ 21.530026]
[ 21.530026] other info that might help us debug this:
[ 21.530026]
[ 21.530026] 1 lock held by multipath.stati/1379:
[ 21.530026] #0: (misc_mtx){--..}, at: [<c02f4b92>] misc_open+0x22/0x120
[ 21.530026]
[ 21.530026] stack backtrace:
[ 21.530026] Pid: 1379, comm: multipath.stati Not tainted 2.6.26-rc2-sched-devel.git #1205
[ 21.530026] [<c014179e>] print_circular_bug_tail+0x6e/0x80
[ 21.530026] [<c01436cd>] __lock_acquire+0xa5d/0x1100
[ 21.530026] [<c0142eec>] ? __lock_acquire+0x27c/0x1100
[ 21.530026] [<c0143de6>] lock_acquire+0x76/0xa0
[ 21.530026] [<c020cca2>] ? ecryptfs_miscdev_open+0x22/0x140
[ 21.530026] [<c020cca2>] ? ecryptfs_miscdev_open+0x22/0x140
[ 21.530026] [<c05d032a>] mutex_lock_nested+0x7a/0x280
[ 21.530026] [<c020cca2>] ? ecryptfs_miscdev_open+0x22/0x140
[ 21.530026] [<c020cca2>] ecryptfs_miscdev_open+0x22/0x140
[ 21.530026] [<c02f4bf2>] misc_open+0x82/0x120
[ 21.530026] [<c0187c26>] chrdev_open+0x86/0x150
[ 21.530026] [<c0183289>] __dentry_open+0xa9/0x260
[ 21.530026] [<c0183487>] nameidata_to_filp+0x47/0x60
[ 21.530026] [<c0187ba0>] ? chrdev_open+0x0/0x150
[ 21.530026] [<c018fda4>] do_filp_open+0x184/0x7a0
[ 21.530026] [<c01168e9>] ? kernel_map_pages+0xb9/0x140
[ 21.530026] [<c018068b>] ? poison_obj+0x2b/0x50
[ 21.530026] [<c011b82b>] ? sub_preempt_count+0x4b/0x70
[ 21.530026] [<c05d1efc>] ? _spin_unlock+0x2c/0x50
[ 21.530026] [<c01830aa>] do_sys_open+0x4a/0xb0
[ 21.530026] [<c0288a8c>] ? trace_hardirqs_on_thunk+0xc/0x10
[ 21.530026] [<c018317e>] sys_open+0x2e/0x40
[ 21.530026] [<c010330e>] syscall_call+0x7/0xb
[ 21.530026] =======================
[ 36.921087] EXT3 FS on sda1, internal journal
[ 38.441628] kjournald starting. Commit interval 5 seconds
[ 38.441628] EXT3 FS on sda5, internal journal
[ 38.511628] EXT3-fs: mounted filesystem with ordered data mode.
[ 41.510014] PM: Removing info for No Bus:vcs1
[ 41.521496] PM: Removing info for No Bus:vcsa1
[ 41.581496] PM: Adding info for No Bus:vcs1
[ 41.590045] PM: Adding info for No Bus:vcsa1
[ 41.590045] PM: Removing info for No Bus:vcs1
[ 41.590045] PM: Removing info for No Bus:vcsa1
[ 41.603425] PM: Adding info for No Bus:vcs1
[ 41.603425] PM: Adding info for No Bus:vcsa1
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