Re: lockdep warning in urb.c:363 usb_submit_urb

Qais Yousef
2020-03-23T16:02:34Z

On 03/23/20 11:54, Alan Stern wrote:
> On Mon, 23 Mar 2020, Oliver Neukum wrote:
>
> > Am Montag, den 23.03.2020, 14:38 +0000 schrieb Qais Yousef:
> > > Hi
> > >
> > > I've hit the following lockdep warning when I trigger hibernate on arm64
> > > platform (Juno-r2)
> > >
> > >
> > > echo suspend > /sys/power/disk
> > > echo disk > /sys/power/state
> > >
> > > I only had a usb flash drive attached to it. Let me know if you need more info.
> >
> > Hi,
> >
> > that is not a lockdep issue, but the hub driver is not properly killing
> > its URB presumably. Yet, the driver looks correct to me. Please use
> > the additional patch and activate dynamic debugging for usbcore.
>
> Was the USB flash drive being used as a swap device for holding the
> hibernation image? That's not likely to work very well. At least, I
> doubt that it has been tested very much.
>
> This diagnostic was suggested by the runtime PM error that occurred
> when the system was trying to store the hibernation image. That's
> probably when the hub driver's URB got restarted.

Yes, sadly it's the only source of storage I have on that device.

When I ran the test I had swapoff, as you can see in the snippet below. When
swap is on I do hibernate and wakeup successfully. At least that's what appears
to be happening to me.

I get a similar splat regardless of swap is on or off.

[ 327.154849] usb usb2: runtime PM trying to activate child device usb2 but parent (7ffb0000.ohci) is not active
[ 327.290355] PM: Cannot find swap device, try swapon -a
[ 327.295533] PM: Cannot get swap writer
[ 327.480758] OOM killer enabled.
[ 327.483939] Restarting tasks ...
[ 327.484229] ------------[ cut here ]------------
[ 327.484664] done.
[ 327.487743] URB 000000000c121c1c submitted while active
[ 327.499622] WARNING: CPU: 1 PID: 296 at drivers/usb/core/urb.c:363 usb_submit_urb+0x3f0/0x520

Thanks

--
Qais Yousef