linux-kernel - Re: kernel 3.2.1: BUG: scheduling while atomic: swapper/0/0/0x10000100

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Date:	Thu, 26 Jan 2012 10:16:36 +0100
From:	Francis Moreau <francis.moro@...il.com>
To:	Arend van Spriel <arend@...adcom.com>
Cc:	Josh Boyer <jwboyer@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
	"John W. Linville" <linville@...driver.com>,
	Greg KH <greg@...ah.com>
Subject: Re: kernel 3.2.1: BUG: scheduling while atomic: swapper/0/0/0x10000100

On Thu, Jan 26, 2012 at 10:04 AM, Arend van Spriel <arend@...adcom.com> wrote:
> On 01/25/2012 05:49 PM, Josh Boyer wrote:
>> On Wed, Jan 25, 2012 at 11:37 AM, Francis Moreau <francis.moro@...il.com> wrote:
>>> Hello,
>>>
>>> On Wed, Jan 25, 2012 at 1:11 PM, Josh Boyer <jwboyer@...il.com> wrote:
>>>>
>>>> We've had a few similar issues reported in Fedora yesterday after we
>>>> rebased to 3.2.1.
>>>
>>> From which kernel did you rebase to 3.2.1 ?
>>
>> Fedora 16 went from 3.1.9 to 3.2.1 earlier this week.  We hadn't been getting
>> reports like this until 3.2.1 showed up.  I asked one of the reporters to try
>> 3.2.0 and they say it recreates there still, so it seems the issue showed up
>> with the 3.2 release.  One user managed to capture the trace below using a
>> kernel with a variety of debug options turned on.  It isn't the same backtrace
>> but it might be related.
>>
>> backtrace:
>> :BUG: sleeping function called from invalid context at
>> drivers/base/power/runtime.c:785
>> :in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper/0
>> :1 lock held by swapper/0/0:
>> : #0:  (&chip->rts51x_suspend_timer){+.-...}, at: [<ffffffff8108d711>]
>> run_timer_softirq+0x111/0x600
>> :Pid: 0, comm: swapper/0 Tainted: G        W    3.2.0-2.fc17.x86_64.debug #1
>> :Call Trace:
>> : <IRQ>  [<ffffffff8105ee7a>] __might_sleep+0x13a/0x1f0
>> : [<ffffffffa00180b0>] ? rts51x_modi_suspend_timer+0x50/0x50 [ums_realtek]
>> : [<ffffffff813fdee3>] __pm_runtime_idle+0xa3/0xb0
>> : [<ffffffffa00180b0>] ? rts51x_modi_suspend_timer+0x50/0x50 [ums_realtek]
>> : [<ffffffff8146ed30>] usb_autopm_put_interface+0x30/0x40
>
> This trace seems to indicate what is wrong. At least for this one user.
> The usb_autopm_put_interface() call seems result in a sleep and the
> rts51x_suspend_timer_fn is holding a lock. Below the code indicated in
> the trace.
>
> runtime.c:
> 768 /**
> 769  * __pm_runtime_idle - Entry point for runtime idle operations.
> 770  * @dev: Device to send idle notification for.
> 771  * @rpmflags: Flag bits.
> 772  *
> 773  * If the RPM_GET_PUT flag is set, decrement the device's usage
> count and
> 774  * return immediately if it is larger than zero.  Then carry out an idle
> 775  * notification, either synchronous or asynchronous.
> 776  *
> 777  * This routine may be called in atomic context if the RPM_ASYNC
> flag is set,
> 778  * or if pm_runtime_irq_safe() has been called.
> 779  */
> 780 int __pm_runtime_idle(struct device *dev, int rpmflags)
> 781 {
> 782         unsigned long flags;
> 783         int retval;
> 784
> 785         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
>
> This issue can either be caused in ums_realtek module or the usb autopm
> code. Have not looked into that.
>

Just a wild guess: it seems that we're affected using different HW
configs with different USB devices, so it would indicate that usb
autopm is the culprit.

-- 
Francis
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