linux-kernel - Re: GPF in run_workqueue()/list_del_init(cwq->worklist.next) on resume (was: Re: Help needed: Resume problems in 2.6.32-rc, perhaps related to preempt

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Date:	Wed, 11 Nov 2009 12:11:00 -0800 (PST)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
cc:	Oleg Nesterov <oleg@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mike Galbraith <efault@....de>, Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Greg KH <gregkh@...e.de>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Tejun Heo <tj@...nel.org>,
	Marcel Holtmann <marcel@...tmann.org>,
	linux-bluetooth@...r.kernel.org
Subject: Re: GPF in run_workqueue()/list_del_init(cwq->worklist.next) on
 resume (was: Re: Help needed: Resume problems in 2.6.32-rc, perhaps related
 to preempt_count leakage in keventd)



On Wed, 11 Nov 2009, Rafael J. Wysocki wrote:
> 
> I applied the patch and this is the result of 'dmesg | grep ERR' after 10-or-so
> consecutive suspend-resume and hibernate-resume cycles:
> 
> [  129.008689] ERR!! btusb_waker+0x0/0x27 [btusb]
> [  166.477373] ERR!! btusb_waker+0x0/0x27 [btusb]
> [  203.983665] ERR!! btusb_waker+0x0/0x27 [btusb]
> [  241.636547] ERR!! btusb_waker+0x0/0x27 [btusb]
> 
> which kind of confirms my previous observation that the problem was not
> reproducible without Bluetooth.

.. and that btusb thing matches my observation that only a few BT drivers 
seem to use workqueues, and btusb_disconnect() isn't doing any work 
cancel.

> I'm going to test the appended patch, then.

Hmm. the USB disconnect doesn't call hci_dev_put(), it calls 
hci_free_dev() and doesn't seem to call the ->destruct thing. 

Although again, maybe that gets called indirectly.

So I'd put the cancel work in the actual disconnect routine. But maybe 
thar's just me.

		Linus
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