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Subject: Re: [BUG]: Possibe recursive locking detected in sysfs
From: John Kacur <jkacur@redhat.com>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>,
       "Eric W. Biederman" <ebiederm@aristanetworks.com>,
       Tejun Heo <tj@kernel.org>, Serge Hallyn <serue@us.ibm.com>,
       "David P. Quigley" <dpquigl@tycho.nsa.gov>,
       James Morris <jmorris@namei.org>
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On Thu, Feb 11, 2010 at 12:11 PM, John Kacur <jkacur@redhat.com> wrote:
> I'm not sure if this one has already been reported. - thanks.
>
> Feb 11 07:24:15 localhost kernel: [ INFO: possible recursive locking detected ]
> Feb 11 07:24:15 localhost kernel: 2.6.33-rc7 #1
> Feb 11 07:24:15 localhost kernel: ---------------------------------------------
> Feb 11 07:24:15 localhost kernel: 94cpufreq/2933 is trying to acquire lock:
> Feb 11 07:24:15 localhost kernel: (s_active){++++.+}, at:
> [<ffffffff81157408>] sysfs_hash_and_remove+0x53/0x6a
> Feb 11 07:24:15 localhost kernel:
> Feb 11 07:24:15 localhost kernel: but task is already holding lock:
> Feb 11 07:24:15 localhost kernel: (s_active){++++.+}, at:
> [<ffffffff81159530>] sysfs_get_active_two+0x24/0x48
> Feb 11 07:24:15 localhost kernel:
> Feb 11 07:24:15 localhost kernel: other info that might help us debug this:
> Feb 11 07:24:15 localhost kernel: 4 locks held by 94cpufreq/2933:
> Feb 11 07:24:15 localhost kernel: #0: ?(&buffer->mutex){+.+.+.}, at:
> [<ffffffff81157dbd>] sysfs_write_file+0x3e/0x12b
> Feb 11 07:24:15 localhost kernel: #1: ?(s_active){++++.+}, at:
> [<ffffffff81159530>] sysfs_get_active_two+0x24/0x48
> Feb 11 07:24:15 localhost kernel: #2: ?(s_active){++++.+}, at:
> [<ffffffff8115953d>] sysfs_get_active_two+0x31/0x48
> Feb 11 07:24:15 localhost kernel: #3: ?(dbs_mutex){+.+.+.}, at:
> [<ffffffffa04bcdb3>] cpufreq_governor_dbs+0x29b/0x348
> [cpufreq_ondemand]
> Feb 11 07:24:15 localhost kernel:
> Feb 11 07:24:15 localhost kernel: stack backtrace:
> Feb 11 07:24:15 localhost kernel: Pid: 2933, comm: 94cpufreq Not
> tainted 2.6.33-rc7 #1
> Feb 11 07:24:15 localhost kernel: Call Trace:
> Feb 11 07:24:15 localhost kernel: [<ffffffff81071f53>]
> __lock_acquire+0xcf6/0xd8b
> Feb 11 07:24:15 localhost kernel: [<ffffffff81070914>] ?
> debug_check_no_locks_freed+0x120/0x12f
> Feb 11 07:24:15 localhost kernel: [<ffffffff8107020e>] ?
> trace_hardirqs_on_caller+0x11f/0x14a
> Feb 11 07:24:15 localhost kernel: [<ffffffff810720c0>] lock_acquire+0xd8/0xf5
> Feb 11 07:24:15 localhost kernel: [<ffffffff81157408>] ?
> sysfs_hash_and_remove+0x53/0x6a
> Feb 11 07:24:15 localhost kernel: [<ffffffff81159231>]
> sysfs_addrm_finish+0xe1/0x175
> Feb 11 07:24:15 localhost kernel: [<ffffffff81157408>] ?
> sysfs_hash_and_remove+0x53/0x6a
> Feb 11 07:24:15 localhost kernel: [<ffffffff8137b1b5>] ?
> sub_preempt_count+0xa3/0xb6
> Feb 11 07:24:15 localhost kernel: [<ffffffff81157408>]
> sysfs_hash_and_remove+0x53/0x6a
> Feb 11 07:24:15 localhost kernel: [<ffffffff8115a59d>]
> sysfs_remove_group+0x91/0xc9
> Feb 11 07:24:15 localhost kernel: [<ffffffffa04bcdc6>]
> cpufreq_governor_dbs+0x2ae/0x348 [cpufreq_ondemand]
> Feb 11 07:24:15 localhost kernel: [<ffffffff8137b1b5>] ?
> sub_preempt_count+0xa3/0xb6
> Feb 11 07:24:15 localhost kernel: [<ffffffff812ab9cc>]
> __cpufreq_governor+0x89/0xc7
> Feb 11 07:24:15 localhost kernel: [<ffffffff812ac7b9>]
> __cpufreq_set_policy+0x18e/0x22a
> Feb 11 07:24:15 localhost kernel: [<ffffffff812accd6>]
> store_scaling_governor+0x199/0x1ed
> Feb 11 07:24:15 localhost kernel: [<ffffffff812ad50d>] ? handle_update+0x0/0x39
> Feb 11 07:24:15 localhost kernel: [<ffffffff8137685d>] ? down_write+0x76/0x7e
> Feb 11 07:24:15 localhost kernel: [<ffffffff812ac607>] store+0x67/0x8b
> Feb 11 07:24:15 localhost kernel: [<ffffffff81157e75>]
> sysfs_write_file+0xf6/0x12b
> Feb 11 07:24:15 localhost kernel: [<ffffffff811003c9>] vfs_write+0xb0/0x10a
> Feb 11 07:24:15 localhost kernel: [<ffffffff811004f1>] sys_write+0x4c/0x75
> Feb 11 07:24:15 localhost kernel: [<ffffffff81002d9b>]
> system_call_fastpath+0x16/0x1b
>

This is still present in 2.6.33-rc8.
I can trigger it every time. I have T500 laptop, the trick is to boot
it up without plugging it in, so it is working on battery power, and
then to shut the lid.
first you get the message from above, and then it does a few more
things before it freezes and I have to hard reboot it.
The above problem does not occur if I have the laptop plugged into the wall.

Here is the 2.6.33-rc8 version of above. If anyone has further
suggestions for debugging, pls let me know.
I've cced the folks that get_maintainer.pl reports for
fs/sysfs/inode.c and fs/sysfs/dir.c

Feb 14 07:35:49 localhost kernel: =============================================
Feb 14 07:35:49 localhost kernel: [ INFO: possible recursive locking detected ]
Feb 14 07:35:49 localhost kernel: 2.6.33-rc8 #1
Feb 14 07:35:49 localhost kernel: ---------------------------------------------
Feb 14 07:35:49 localhost kernel: 94cpufreq/2914 is trying to acquire lock:
Feb 14 07:35:49 localhost kernel: (s_active){++++.+}, at:
[<ffffffff81157478>] sysfs_hash_and_remove+0x53/0x6a
Feb 14 07:35:49 localhost kernel:
Feb 14 07:35:49 localhost kernel: but task is already holding lock:
Feb 14 07:35:49 localhost kernel: (s_active){++++.+}, at:
[<ffffffff811595a0>] sysfs_get_active_two+0x24/0x48
Feb 14 07:35:49 localhost kernel:
Feb 14 07:35:49 localhost kernel: other info that might help us debug this:
Feb 14 07:35:49 localhost kernel: 4 locks held by 94cpufreq/2914:
Feb 14 07:35:49 localhost kernel: #0:  (&buffer->mutex){+.+.+.}, at:
[<ffffffff81157e2d>] sysfs_write_file+0x3e/0x12b
Feb 14 07:35:49 localhost kernel: #1:  (s_active){++++.+}, at:
[<ffffffff811595a0>] sysfs_get_active_two+0x24/0x48
Feb 14 07:35:49 localhost kernel: #2:  (s_active){++++.+}, at:
[<ffffffff811595ad>] sysfs_get_active_two+0x31/0x48
Feb 14 07:35:49 localhost kernel: #3:  (dbs_mutex){+.+.+.}, at:
[<ffffffffa04c0dbe>] cpufreq_governor_dbs+0x29b/0x345
[cpufreq_ondemand]
Feb 14 07:35:49 localhost kernel:
Feb 14 07:35:49 localhost kernel: stack backtrace:
Feb 14 07:35:49 localhost kernel: Pid: 2914, comm: 94cpufreq Not
tainted 2.6.33-rc8 #1
Feb 14 07:35:49 localhost kernel: Call Trace:
Feb 14 07:35:49 localhost kernel: [<ffffffff81071f53>]
__lock_acquire+0xcf6/0xd8b
Feb 14 07:35:49 localhost kernel: [<ffffffff81070914>] ?
debug_check_no_locks_freed+0x120/0x12f
Feb 14 07:35:49 localhost kernel: [<ffffffff8107020e>] ?
trace_hardirqs_on_caller+0x11f/0x14a
Feb 14 07:35:49 localhost kernel: [<ffffffff810720c0>] lock_acquire+0xd8/0xf5
Feb 14 07:35:49 localhost kernel: [<ffffffff81157478>] ?
sysfs_hash_and_remove+0x53/0x6a
Feb 14 07:35:49 localhost kernel: [<ffffffff811592a1>]
sysfs_addrm_finish+0xe1/0x175
Feb 14 07:35:49 localhost kernel: [<ffffffff81157478>] ?
sysfs_hash_and_remove+0x53/0x6a
Feb 14 07:35:49 localhost kernel: [<ffffffff8137b335>] ?
sub_preempt_count+0xa3/0xb6
Feb 14 07:35:49 localhost kernel: [<ffffffff81157478>]
sysfs_hash_and_remove+0x53/0x6a
Feb 14 07:35:49 localhost kernel: [<ffffffff8115a60d>]
sysfs_remove_group+0x91/0xc9
Feb 14 07:35:49 localhost kernel: [<ffffffffa04c0dd1>]
cpufreq_governor_dbs+0x2ae/0x345 [cpufreq_ondemand]
Feb 14 07:35:49 localhost kernel: [<ffffffff8137b335>] ?
sub_preempt_count+0xa3/0xb6
Feb 14 07:35:49 localhost kernel: [<ffffffff812aba60>]
__cpufreq_governor+0x89/0xc7
Feb 14 07:35:49 localhost kernel: [<ffffffff812ac84d>]
__cpufreq_set_policy+0x18e/0x22a
Feb 14 07:35:49 localhost kernel: [<ffffffff812acd6a>]
store_scaling_governor+0x199/0x1ed
Feb 14 07:35:49 localhost kernel: [<ffffffff812ad5a1>] ? handle_update+0x0/0x39
Feb 14 07:35:49 localhost kernel: [<ffffffff813769ad>] ? down_write+0x76/0x7e
Feb 14 07:35:49 localhost kernel: [<ffffffff812ac69b>] store+0x67/0x8b
Feb 14 07:35:49 localhost kernel: [<ffffffff81157ee5>]
sysfs_write_file+0xf6/0x12b
Feb 14 07:35:49 localhost kernel: [<ffffffff811003c9>] vfs_write+0xb0/0x10a
Feb 14 07:35:49 localhost kernel: [<ffffffff811004f1>] sys_write+0x4c/0x75
Feb 14 07:35:49 localhost kernel: [<ffffffff81002d9b>]
system_call_fastpath+0x16/0x1b
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