linux-kernel - Re: [Patch 2/2] block: add sysfs lockdep class for iosched

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Date:	Mon, 08 Feb 2010 14:50:12 -0600
From:	Larry Finger <Larry.Finger@...inger.net>
To:	Amerigo Wang <amwang@...hat.com>
CC:	linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Peter Zijlstra <peterz@...radead.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Jens Axboe <jens.axboe@...cle.com>,
	Miles Lane <miles.lane@...il.com>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	akpm@...ux-foundation.org
Subject: Re: [Patch 2/2] block: add sysfs lockdep class for iosched

On 02/08/2010 03:52 AM, Amerigo Wang wrote:
> Similar to the previous PM case, in iosched, we hold an s_active
> lock to store "scheduler", meanwhile we want to remove "iosched/*"
> files.
> 
> This patch depends on the previous one. I tested it on my machine,
> it fixes the problem.
> 
> Reported-by: Hugh Dickins <hugh.dickins@...cali.co.uk>
> Signed-off-by: WANG Cong <amwang@...hat.com>
> Cc: Jens Axboe <jens.axboe@...cle.com>

After applying the 2 patches to 2.6.33-rc7, I get the following:

ACPI: bus type pci registered
PCI: MMCONFIG for domain 0000 [bus 00-09] at [mem 0xe0000000-0xe09fffff] (base
0xe0000000)
PCI: MMCONFIG at [mem 0xe0000000-0xe09fffff] reserved in E820
PCI: Using configuration type 1 for base access
INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
Pid: 1, comm: swapper Not tainted 2.6.33-rc7-Linus-00010-g6339204-dirty #181
Call Trace:
 [<ffffffff8107c6e6>] __lock_acquire+0xf86/0x1d30
 [<ffffffff81078e7f>] ? lockdep_init_map+0x5f/0x5d0
 [<ffffffff8107d52b>] lock_acquire+0x9b/0x120
 [<ffffffff81167a93>] ? sysfs_addrm_finish+0x43/0x70
 [<ffffffff81167243>] sysfs_deactivate+0xc3/0x110
 [<ffffffff81167a93>] ? sysfs_addrm_finish+0x43/0x70
 [<ffffffff813124d3>] ? mutex_lock_nested+0x243/0x300
 [<ffffffff81167a93>] sysfs_addrm_finish+0x43/0x70
 [<ffffffff81167af6>] remove_dir+0x36/0x40
 [<ffffffff81167b09>] sysfs_remove_subdir+0x9/0x10
 [<ffffffff81168ff6>] sysfs_remove_group+0x66/0xf0
 [<ffffffff81861555>] param_sysfs_init+0x102/0x277
 [<ffffffff8124a5bd>] ? sysdev_create_file+0xd/0x10
 [<ffffffff8130fe46>] ? register_cpu+0xa3/0xa5
 [<ffffffff81861453>] ? param_sysfs_init+0x0/0x277
 [<ffffffff810001d7>] do_one_initcall+0x37/0x190
 [<ffffffff8184c6d0>] kernel_init+0x14f/0x1a5
 [<ffffffff81003bd4>] kernel_thread_helper+0x4/0x10
 [<ffffffff8131417c>] ? restore_args+0x0/0x30
 [<ffffffff8184c581>] ? kernel_init+0x0/0x1a5
 [<ffffffff81003bd0>] ? kernel_thread_helper+0x0/0x10

This dump does not occur with standard 2.6.33-rc7. As the above turns off the
locking correctness validator, I cannot really test to see what happens when
suspending.

Larry
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