Re: USB device cannot be reconnected and khubd "blocked for morethan 120 seconds"

From: Lan Tianyu
Date: Sat Jan 12 2013 - 05:12:21 EST


On 2013å1æ12æ 15:48:59, Alex Riesen wrote:
On Fri, Jan 11, 2013 at 10:04 PM, Alex Riesen <raa.lkml@xxxxxxxxx> wrote:
Hi,

the USB stick (an Cruzer Titanium 2GB) was not recognized at any of
the USB ports of this system (an System76 lemu4 laptop, XHCI device)
after it was removed. If I attempt to insert it again in any of the
ports (one of the two USB3, or the USB2) the led on the stick lights
up shortly and if off again. There is no media detection messages in
the dmesg output, only that from the first time:

usb 1-1.2: new high-speed USB device number 3 using ehci-pci
usb 1-1.2: New USB device found, idVendor=0781, idProduct=5408
usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1.2: Product: U3 Titanium
usb 1-1.2: Manufacturer: SanDisk Corporation
usb 1-1.2: SerialNumber: 0000187A3A60F1E9
scsi6 : usb-storage 1-1.2:1.0
io scheduler deadline registered (default)
usb 1-1.2: USB disconnect, device number 3

The kernel is v3.8-rc3. I never had this problem in 3.7. I could almost
reproduce the problem later in a simplified setup (init=/bin/bash) on
USB3 ports by inserting and removing the stick quickly. Almost - because
the USB3 ports recovered after some time, while the USB2 port never
experienced the problem.

One more detail: I usually use the "noop" elevator. That time it was
the "deadline". And I just reproduced it easily with "deadline".
Can you provide the output of dmesg with CONFIG_USB_DEBUG? This will
be helpful.
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Best regards
Tianyu Lan
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